{"id":1079,"date":"2024-12-19T15:24:37","date_gmt":"2024-12-19T08:24:37","guid":{"rendered":"https:\/\/www.pgtutorial.com\/?page_id=1079"},"modified":"2025-01-05T20:16:03","modified_gmt":"2025-01-05T13:16:03","slug":"postgresql-row_number","status":"publish","type":"page","link":"https:\/\/www.pgtutorial.com\/postgresql-window-functions\/postgresql-row_number\/","title":{"rendered":"PostgreSQL ROW_NUMBER Window Function"},"content":{"rendered":"\n<p><strong>Summary<\/strong>: in this tutorial, you&#8217;ll learn how to use the PostgreSQL <code>ROW_NUMBER<\/code> window function to assign unique sequential integers to rows within a partition of a result set.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\" id='getting-started-with-the-postgresql-row_number-window-function'>Getting Started with the PostgreSQL ROW_NUMBER window function <a href=\"#getting-started-with-the-postgresql-row_number-window-function\" class=\"anchor\" id=\"getting-started-with-the-postgresql-row_number-window-function\" title=\"Anchor for Getting Started with the PostgreSQL ROW_NUMBER window function\">#<\/a><\/h2>\n\n\n\n<p>The <code>ROW_NUMBER()<\/code> is a <a href=\"https:\/\/www.pgtutorial.com\/postgresql-window-functions\/\">window function<\/a> that assigns unique sequential integers to rows within a partition of a result set.<\/p>\n\n\n\n<p>The <code>ROW_NUMBER()<\/code> function can be helpful for queries that perform ranking, pagination, and identifying duplicate rows.<\/p>\n\n\n\n<p>Here&#8217;s the basic syntax of the <code>ROW_NUMBER()<\/code> function:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-1\" data-shcb-language-name=\"PostgreSQL SQL dialect and PL\/pgSQL\" data-shcb-language-slug=\"pgsql\"><span><code class=\"hljs language-pgsql\">ROW_NUMBER() <span class=\"hljs-keyword\">OVER<\/span> (\n\u00a0 \u00a0\u00a0&#91;<span class=\"hljs-keyword\">PARTITION<\/span> <span class=\"hljs-keyword\">BY<\/span> expression_list]\n\u00a0 \u00a0\u00a0&#91;<span class=\"hljs-keyword\">ORDER<\/span> <span class=\"hljs-keyword\">BY<\/span> expression_list]\n)<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-1\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">PostgreSQL SQL dialect and PL\/pgSQL<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">pgsql<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p>In this syntax:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><code>PARTITION BY<\/code>: Divides the result set into partitions where the <code>ROW_NUMBER()<\/code> function applies.<\/li>\n\n\n\n<li><code>ORDER BY<\/code>: Sorts the rows within each partition.<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\" id='basic-postgresql-row_number-window-function-examples'>Basic PostgreSQL ROW_NUMBER() window function examples <a href=\"#basic-postgresql-row_number-window-function-examples\" class=\"anchor\" id=\"basic-postgresql-row_number-window-function-examples\" title=\"Anchor for Basic PostgreSQL ROW_NUMBER() window function examples\">#<\/a><\/h2>\n\n\n\n<p>Let&#8217;s explore some examples of using the <code>ROW_NUMBER()<\/code> function with the <code>products<\/code> table from the <code>inventory<\/code> database:<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"159\" height=\"254\" src=\"https:\/\/www.pgtutorial.com\/wp-content\/uploads\/2024\/12\/products.png\" alt=\"row_number function with products table\" class=\"wp-image-1051\"\/><\/figure>\n\n\n\n<p>The following example uses the <code>ROW_NUMBER()<\/code> function to assign a unique row number to each row in the <code>products<\/code> table:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-2\" data-shcb-language-name=\"PostgreSQL SQL dialect and PL\/pgSQL\" data-shcb-language-slug=\"pgsql\"><span><code class=\"hljs language-pgsql\"><span class=\"hljs-keyword\">SELECT<\/span>\n  product_name,\n  price,\n  ROW_NUMBER() <span class=\"hljs-keyword\">OVER<\/span> () <span class=\"hljs-keyword\">as<\/span> row_number\n<span class=\"hljs-keyword\">FROM<\/span>\n  products;<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-2\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">PostgreSQL SQL dialect and PL\/pgSQL<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">pgsql<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p><a href=\"https:\/\/www.pgtutorial.com\/playground\/?q=U0VMRUNUIHByb2R1Y3RfbmFtZSwgcHJpY2UsIFJPV19OVU1CRVIoKSBPVkVSICgpIGFzIHJvd19udW1iZXIgRlJPTSBwcm9kdWN0czs%3D\" target=\"_blank\" rel=\"noreferrer noopener\">Try it<\/a><\/p>\n\n\n\n<p>Output<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-3\" data-shcb-language-name=\"PostgreSQL SQL dialect and PL\/pgSQL\" data-shcb-language-slug=\"pgsql\"><span><code class=\"hljs language-pgsql\">        product_name        |  price  | row_number\n<span class=\"hljs-comment\">----------------------------+---------+------------<\/span>\n Samsung Galaxy S24         |  <span class=\"hljs-number\">999.99<\/span> |          <span class=\"hljs-number\">1<\/span>\n Apple iPhone <span class=\"hljs-number\">15<\/span>            | <span class=\"hljs-number\">1099.99<\/span> |          <span class=\"hljs-number\">2<\/span>\n Huawei Mate <span class=\"hljs-number\">60<\/span>             |  <span class=\"hljs-number\">899.99<\/span> |          <span class=\"hljs-number\">3<\/span>\n Xiaomi Mi <span class=\"hljs-number\">14<\/span>               |  <span class=\"hljs-number\">799.99<\/span> |          <span class=\"hljs-number\">4<\/span>\n Sony Xperia <span class=\"hljs-number\">1<\/span> VI           |  <span class=\"hljs-number\">949.99<\/span> |          <span class=\"hljs-number\">5<\/span>\n Samsung Galaxy Z Fold <span class=\"hljs-number\">5<\/span>    | <span class=\"hljs-number\">1799.99<\/span> |          <span class=\"hljs-number\">6<\/span>\n Apple iPhone <span class=\"hljs-number\">15<\/span> Pro Max    | <span class=\"hljs-number\">1299.99<\/span> |          <span class=\"hljs-number\">7<\/span>\n...<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-3\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">PostgreSQL SQL dialect and PL\/pgSQL<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">pgsql<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p>In this example:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>The <code>FROM<\/code> clause examines all rows from the <code>products<\/code> table.<\/li>\n\n\n\n<li>The <code>SELECT<\/code> clause retrieves the product name and price and calls the <code>ROW_NUMBER()<\/code> function to generate a unique row number for each row.<\/li>\n<\/ul>\n\n\n\n<p>If you want to control the order of rows, you need to use the <code>ORDER BY<\/code> clause in the <code>OVER<\/code>, not in the <code>SELECT<\/code> statement:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-4\" data-shcb-language-name=\"PostgreSQL SQL dialect and PL\/pgSQL\" data-shcb-language-slug=\"pgsql\"><span><code class=\"hljs language-pgsql\"><span class=\"hljs-keyword\">SELECT<\/span>\n  product_name,\n  price,\n  ROW_NUMBER() <span class=\"hljs-keyword\">OVER<\/span> (<span class=\"hljs-keyword\">ORDER<\/span> <span class=\"hljs-keyword\">BY<\/span>  product_name) row_number\n<span class=\"hljs-keyword\">FROM<\/span>\n  products;<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-4\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">PostgreSQL SQL dialect and PL\/pgSQL<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">pgsql<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p><a href=\"https:\/\/www.pgtutorial.com\/playground\/?q=U0VMRUNUIHByb2R1Y3RfbmFtZSwgcHJpY2UsIFJPV19OVU1CRVIoKSBPVkVSICggT1JERVIgQlkgcHJvZHVjdF9uYW1lICkgcm93X251bWJlciBGUk9NIHByb2R1Y3RzOw%3D%3D\" target=\"_blank\" rel=\"noreferrer noopener\">Try it<\/a><\/p>\n\n\n\n<p>Output:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-5\" data-shcb-language-name=\"PostgreSQL SQL dialect and PL\/pgSQL\" data-shcb-language-slug=\"pgsql\"><span><code class=\"hljs language-pgsql\">        product_name        |  price  | row_number\n<span class=\"hljs-comment\">----------------------------+---------+------------<\/span>\n Apple AirPods Pro <span class=\"hljs-number\">3<\/span>        |  <span class=\"hljs-number\">249.99<\/span> |          <span class=\"hljs-number\">1<\/span>\n Apple iMac <span class=\"hljs-number\">24<\/span>\"             | 1299.99 |          2\n Apple iPad Pro 12.9        | 1099.99 |          3\n Apple iPhone 15            | 1099.99 |          4\n Apple iPhone 15 Pro Max    | 1299.99 |          5\n Apple Watch Series 9       |  399.99 |          6\n Bose SoundLink Max         |  399.99 |          7\n Dell Inspiron 27           |  999.99 |          8\n...<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-5\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">PostgreSQL SQL dialect and PL\/pgSQL<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">pgsql<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p>In this example:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>The <code>FROM<\/code> clause examines all rows from the <code>products<\/code> table.<\/li>\n\n\n\n<li>The <code>SELECT<\/code> clause retrieves the product name and price and calls the <code>ROW_NUMBER()<\/code> function to generate a sequential row number for each row sorted by the product name in ascending order.<\/li>\n<\/ul>\n\n\n\n<p>To assign row numbers to products within each category, you can use the <code>PARTITION BY<\/code> clause:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-6\" data-shcb-language-name=\"PostgreSQL SQL dialect and PL\/pgSQL\" data-shcb-language-slug=\"pgsql\"><span><code class=\"hljs language-pgsql\"><span class=\"hljs-keyword\">SELECT<\/span>\n  product_name,\n  price,\n  category_id,\n  ROW_NUMBER() <span class=\"hljs-keyword\">OVER<\/span> (\n    <span class=\"hljs-keyword\">PARTITION<\/span> <span class=\"hljs-keyword\">BY<\/span> category_id\n    <span class=\"hljs-keyword\">ORDER<\/span> <span class=\"hljs-keyword\">BY<\/span> product_name\n  ) row_number\n<span class=\"hljs-keyword\">FROM<\/span>\n  products;<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-6\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">PostgreSQL SQL dialect and PL\/pgSQL<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">pgsql<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p><a href=\"https:\/\/www.pgtutorial.com\/playground\/?q=U0VMRUNUIHByb2R1Y3RfbmFtZSwgcHJpY2UsIGNhdGVnb3J5X2lkLCBST1dfTlVNQkVSKCkgT1ZFUiAoIFBBUlRJVElPTiBCWSBjYXRlZ29yeV9pZCBPUkRFUiBCWSBwcm9kdWN0X25hbWUgKSByb3dfbnVtYmVyIEZST00gcHJvZHVjdHM7\" target=\"_blank\" rel=\"noreferrer noopener\">Try it<\/a><\/p>\n\n\n\n<p>Output:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-7\" data-shcb-language-name=\"PostgreSQL SQL dialect and PL\/pgSQL\" data-shcb-language-slug=\"pgsql\"><span><code class=\"hljs language-pgsql\">        product_name        |  price  | category_id | row_number\n<span class=\"hljs-comment\">----------------------------+---------+-------------+------------<\/span>\n Apple iPhone <span class=\"hljs-number\">15<\/span>            | <span class=\"hljs-number\">1099.99<\/span> |           <span class=\"hljs-number\">3<\/span> |          <span class=\"hljs-number\">1<\/span>\n Apple iPhone <span class=\"hljs-number\">15<\/span> Pro Max    | <span class=\"hljs-number\">1299.99<\/span> |           <span class=\"hljs-number\">3<\/span> |          <span class=\"hljs-number\">2<\/span>\n Huawei Mate <span class=\"hljs-number\">60<\/span>             |  <span class=\"hljs-number\">899.99<\/span> |           <span class=\"hljs-number\">3<\/span> |          <span class=\"hljs-number\">3<\/span>\n Samsung Galaxy S24         |  <span class=\"hljs-number\">999.99<\/span> |           <span class=\"hljs-number\">3<\/span> |          <span class=\"hljs-number\">4<\/span>\n Samsung Galaxy Z Fold <span class=\"hljs-number\">5<\/span>    | <span class=\"hljs-number\">1799.99<\/span> |           <span class=\"hljs-number\">3<\/span> |          <span class=\"hljs-number\">5<\/span>\n Sony Xperia <span class=\"hljs-number\">1<\/span> VI           |  <span class=\"hljs-number\">949.99<\/span> |           <span class=\"hljs-number\">3<\/span> |          <span class=\"hljs-number\">6<\/span>\n Xiaomi Mi <span class=\"hljs-number\">14<\/span>               |  <span class=\"hljs-number\">799.99<\/span> |           <span class=\"hljs-number\">3<\/span> |          <span class=\"hljs-number\">7<\/span>\n...<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-7\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">PostgreSQL SQL dialect and PL\/pgSQL<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">pgsql<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p>In this example:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>The <code>PARTITION BY<\/code> clause divides the rows into partitions by category id.<\/li>\n\n\n\n<li>The <code>ORDER BY<\/code> clause sorts rows in each partition by the product name.<\/li>\n\n\n\n<li>The <code>ROW_NUMBER()<\/code> assigns a sequential integer to products in each partition.<\/li>\n<\/ul>\n\n\n\n<p class=\"note\">Notice that the <code>ROW_NUMBER()<\/code> function resets the row number for each partition.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\" id='postgresql-row_number-function-applications'>PostgreSQL ROW_NUMBER function applications <a href=\"#postgresql-row_number-function-applications\" class=\"anchor\" id=\"postgresql-row_number-function-applications\" title=\"Anchor for PostgreSQL ROW_NUMBER function applications\">#<\/a><\/h2>\n\n\n\n<p>Let&#8217;s explore some applications of the <code>ROW_NUMBER()<\/code> function.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id='pagination'>Pagination <a href=\"#pagination\" class=\"anchor\" id=\"pagination\" title=\"Anchor for Pagination\">#<\/a><\/h3>\n\n\n\n<p>The <code>ROW_NUMBER()<\/code> function allows you to paginate data by retrieving a specific subset of rows from a large result set.<\/p>\n\n\n\n<p>The following example uses the <code>ROW_NUMBER()<\/code> function with a common table expression (CTE) to retrieve the row numbers 11 to 20:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-8\" data-shcb-language-name=\"PostgreSQL SQL dialect and PL\/pgSQL\" data-shcb-language-slug=\"pgsql\"><span><code class=\"hljs language-pgsql\"><span class=\"hljs-keyword\">WITH<\/span> numbered_products <span class=\"hljs-keyword\">AS<\/span> (\n    <span class=\"hljs-keyword\">SELECT<\/span>\n      product_id,\n      product_name,\n      price,\n      ROW_NUMBER() <span class=\"hljs-keyword\">OVER<\/span> (\n        <span class=\"hljs-keyword\">ORDER<\/span> <span class=\"hljs-keyword\">BY<\/span> product_name\n      ) row_number\n    <span class=\"hljs-keyword\">FROM<\/span>\n      products\n)\n<span class=\"hljs-keyword\">SELECT<\/span>\n  product_id,\n  product_name,\n  price\n<span class=\"hljs-keyword\">FROM<\/span>\n  numbered_products\n<span class=\"hljs-keyword\">WHERE<\/span>\n  row_number <span class=\"hljs-keyword\">BETWEEN<\/span> <span class=\"hljs-number\">11<\/span> <span class=\"hljs-keyword\">AND<\/span> <span class=\"hljs-number\">20<\/span>\n<span class=\"hljs-keyword\">ORDER<\/span> <span class=\"hljs-keyword\">BY<\/span> product_name;<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-8\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">PostgreSQL SQL dialect and PL\/pgSQL<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">pgsql<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p><a href=\"https:\/\/www.pgtutorial.com\/playground\/?q=V0lUSCBudW1iZXJlZF9wcm9kdWN0cyBBUyAoIFNFTEVDVCBwcm9kdWN0X2lkLCBwcm9kdWN0X25hbWUsIHByaWNlLCBST1dfTlVNQkVSKCkgT1ZFUiAoIE9SREVSIEJZIHByb2R1Y3RfbmFtZSApIHJvd19udW1iZXIgRlJPTSBwcm9kdWN0cyApIFNFTEVDVCBwcm9kdWN0X2lkLCBwcm9kdWN0X25hbWUsIHByaWNlIEZST00gbnVtYmVyZWRfcHJvZHVjdHMgV0hFUkUgcm93X251bWJlciBCRVRXRUVOIDExIEFORCAyMDs%3D\" target=\"_blank\" rel=\"noreferrer noopener\">Try it<\/a><\/p>\n\n\n\n<p>Output:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-9\" data-shcb-language-name=\"PostgreSQL SQL dialect and PL\/pgSQL\" data-shcb-language-slug=\"pgsql\"><span><code class=\"hljs language-pgsql\"> product_id |        product_name        |  price\n<span class=\"hljs-comment\">------------+----------------------------+---------<\/span>\n          <span class=\"hljs-number\">3<\/span> | Huawei Mate <span class=\"hljs-number\">60<\/span>             |  <span class=\"hljs-number\">899.99<\/span>\n         <span class=\"hljs-number\">23<\/span> | Lenovo ThinkPad X1 Carbon  | <span class=\"hljs-number\">1599.99<\/span>\n         <span class=\"hljs-number\">17<\/span> | LG G3 OLED                 | <span class=\"hljs-number\">2499.99<\/span>\n         <span class=\"hljs-number\">14<\/span> | LG OLED TV C3              | <span class=\"hljs-number\">1999.99<\/span>\n         <span class=\"hljs-number\">22<\/span> | Microsoft Surface Laptop <span class=\"hljs-number\">5<\/span> | <span class=\"hljs-number\">1299.99<\/span>\n         <span class=\"hljs-number\">11<\/span> | Samsung Galaxy Buds Pro <span class=\"hljs-number\">2<\/span>  |  <span class=\"hljs-number\">199.99<\/span>\n          <span class=\"hljs-number\">1<\/span> | Samsung Galaxy S24         |  <span class=\"hljs-number\">999.99<\/span>\n          <span class=\"hljs-number\">8<\/span> | Samsung Galaxy Tab S9      |  <span class=\"hljs-number\">699.99<\/span>\n         <span class=\"hljs-number\">13<\/span> | Samsung Galaxy Watch <span class=\"hljs-number\">6<\/span>     |  <span class=\"hljs-number\">349.99<\/span>\n          <span class=\"hljs-number\">6<\/span> | Samsung Galaxy Z Fold <span class=\"hljs-number\">5<\/span>    | <span class=\"hljs-number\">1799.99<\/span><\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-9\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">PostgreSQL SQL dialect and PL\/pgSQL<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">pgsql<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p>How it works.<\/p>\n\n\n\n<p>First, the query of the CTE assigns a sequential number to each row from the <code>products<\/code> table sorted by the product name:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-10\" data-shcb-language-name=\"PostgreSQL SQL dialect and PL\/pgSQL\" data-shcb-language-slug=\"pgsql\"><span><code class=\"hljs language-pgsql\"><span class=\"hljs-keyword\">SELECT<\/span>\n  product_id,\n  product_name,\n  price,\n  ROW_NUMBER() <span class=\"hljs-keyword\">OVER<\/span> (\n    <span class=\"hljs-keyword\">ORDER<\/span> <span class=\"hljs-keyword\">BY<\/span>\n      product_name\n  ) row_number\n<span class=\"hljs-keyword\">FROM<\/span>\n  products;<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-10\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">PostgreSQL SQL dialect and PL\/pgSQL<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">pgsql<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p><a href=\"https:\/\/www.pgtutorial.com\/playground\/?q=U0VMRUNUIHByb2R1Y3RfaWQsIHByb2R1Y3RfbmFtZSwgcHJpY2UsIFJPV19OVU1CRVIoKSBPVkVSICggT1JERVIgQlkgcHJvZHVjdF9uYW1lICkgcm93X251bWJlciBGUk9NIHByb2R1Y3Rz\" target=\"_blank\" rel=\"noreferrer noopener\">Try it<\/a><\/p>\n\n\n\n<p>Output:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-11\" data-shcb-language-name=\"PostgreSQL SQL dialect and PL\/pgSQL\" data-shcb-language-slug=\"pgsql\"><span><code class=\"hljs language-pgsql\"> product_id |        product_name        |  price  | row_number\n<span class=\"hljs-comment\">------------+----------------------------+---------+------------<\/span>\n         <span class=\"hljs-number\">10<\/span> | Apple AirPods Pro <span class=\"hljs-number\">3<\/span>        |  <span class=\"hljs-number\">249.99<\/span> |          <span class=\"hljs-number\">1<\/span>\n         <span class=\"hljs-number\">24<\/span> | Apple iMac <span class=\"hljs-number\">24<\/span>\"             | 1299.99 |          2\n          9 | Apple iPad Pro 12.9        | 1099.99 |          3\n          2 | Apple iPhone 15            | 1099.99 |          4\n          7 | Apple iPhone 15 Pro Max    | 1299.99 |          5\n         12 | Apple Watch Series 9       |  399.99 |          6\n         19 | Bose SoundLink Max         |  399.99 |          7\n         25 | Dell Inspiron 27           |  999.99 |          8\n         20 | Dell XPS 15                | 1499.99 |          9\n         21 | HP Spectre x360            | 1399.99 |         10\n          3 | Huawei Mate 60             |  899.99 |         11\n         23 | Lenovo ThinkPad X1 Carbon  | 1599.99 |         12\n         17 | LG G3 OLED                 | 2499.99 |         13\n         14 | LG OLED TV C3              | 1999.99 |         14\n         22 | Microsoft Surface Laptop 5 | 1299.99 |         15\n         11 | Samsung Galaxy Buds Pro 2  |  199.99 |         16\n          1 | Samsung Galaxy S24         |  999.99 |         17\n          8 | Samsung Galaxy Tab S9      |  699.99 |         18\n         13 | Samsung Galaxy Watch 6     |  349.99 |         19\n          6 | Samsung Galaxy Z Fold 5    | 1799.99 |         20\n...<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-11\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">PostgreSQL SQL dialect and PL\/pgSQL<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">pgsql<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p>Second, the outer query retrieves the rows with row numbers from 11 to 20:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-12\" data-shcb-language-name=\"PostgreSQL SQL dialect and PL\/pgSQL\" data-shcb-language-slug=\"pgsql\"><span><code class=\"hljs language-pgsql\"><span class=\"hljs-keyword\">SELECT<\/span>\n  product_id,\n  product_name,\n  price\n<span class=\"hljs-keyword\">FROM<\/span>\n  numbered_products\n<span class=\"hljs-keyword\">WHERE<\/span>\n  row_number <span class=\"hljs-keyword\">BETWEEN<\/span> <span class=\"hljs-number\">11<\/span> <span class=\"hljs-keyword\">AND<\/span> <span class=\"hljs-number\">20<\/span>;<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-12\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">PostgreSQL SQL dialect and PL\/pgSQL<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">pgsql<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<h3 class=\"wp-block-heading\" id='getting-top-n-records'>Getting Top N records <a href=\"#getting-top-n-records\" class=\"anchor\" id=\"getting-top-n-records\" title=\"Anchor for Getting Top N records\">#<\/a><\/h3>\n\n\n\n<p>The following example uses the <code>ROW_NUMBER()<\/code> function to retrieve the top two most expensive products in each category:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-13\" data-shcb-language-name=\"PostgreSQL SQL dialect and PL\/pgSQL\" data-shcb-language-slug=\"pgsql\"><span><code class=\"hljs language-pgsql\"><span class=\"hljs-keyword\">WITH<\/span> ranked_products <span class=\"hljs-keyword\">AS<\/span> (\n    <span class=\"hljs-keyword\">SELECT<\/span>\n      product_id,\n      product_name,\n      category_id,\n      price,\n      ROW_NUMBER() <span class=\"hljs-keyword\">OVER<\/span> (\n        <span class=\"hljs-keyword\">PARTITION<\/span> <span class=\"hljs-keyword\">BY<\/span>\n          category_id\n        <span class=\"hljs-keyword\">ORDER<\/span> <span class=\"hljs-keyword\">BY<\/span>\n          price <span class=\"hljs-keyword\">DESC<\/span>\n      ) <span class=\"hljs-keyword\">AS<\/span> rank\n    <span class=\"hljs-keyword\">FROM<\/span>\n      products\n  )\n<span class=\"hljs-keyword\">SELECT<\/span>\n  product_id,\n  product_name,\n  category_id,\n  price\n<span class=\"hljs-keyword\">FROM<\/span>\n  ranked_products\n<span class=\"hljs-keyword\">WHERE<\/span>\n  rank &lt;= <span class=\"hljs-number\">2<\/span>;<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-13\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">PostgreSQL SQL dialect and PL\/pgSQL<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">pgsql<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p><a href=\"https:\/\/www.pgtutorial.com\/playground\/?q=V0lUSCByYW5rZWRfcHJvZHVjdHMgQVMgKCBTRUxFQ1QgcHJvZHVjdF9pZCwgcHJvZHVjdF9uYW1lLCBjYXRlZ29yeV9pZCwgcHJpY2UsIFJPV19OVU1CRVIoKSBPVkVSICggUEFSVElUSU9OIEJZIGNhdGVnb3J5X2lkIE9SREVSIEJZIHByaWNlIERFU0MgKSBBUyByYW5rIEZST00gcHJvZHVjdHMgKSBTRUxFQ1QgcHJvZHVjdF9pZCwgcHJvZHVjdF9uYW1lLCBjYXRlZ29yeV9pZCwgcHJpY2UgRlJPTSByYW5rZWRfcHJvZHVjdHMgV0hFUkUgcmFuayA8PSAyOw%3D%3D\" target=\"_blank\" rel=\"noreferrer noopener\">Try it<\/a><\/p>\n\n\n\n<p>Output:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-14\" data-shcb-language-name=\"PostgreSQL SQL dialect and PL\/pgSQL\" data-shcb-language-slug=\"pgsql\"><span><code class=\"hljs language-pgsql\"> product_id |       product_name        | category_id |  price\n<span class=\"hljs-comment\">------------+---------------------------+-------------+---------<\/span>\n          <span class=\"hljs-number\">6<\/span> | Samsung Galaxy Z Fold <span class=\"hljs-number\">5<\/span>   |           <span class=\"hljs-number\">3<\/span> | <span class=\"hljs-number\">1799.99<\/span>\n          <span class=\"hljs-number\">7<\/span> | Apple iPhone <span class=\"hljs-number\">15<\/span> Pro Max   |           <span class=\"hljs-number\">3<\/span> | <span class=\"hljs-number\">1299.99<\/span>\n          <span class=\"hljs-number\">9<\/span> | Apple iPad Pro <span class=\"hljs-number\">12.9<\/span>       |           <span class=\"hljs-number\">4<\/span> | <span class=\"hljs-number\">1099.99<\/span>\n          <span class=\"hljs-number\">8<\/span> | Samsung Galaxy Tab S9     |           <span class=\"hljs-number\">4<\/span> |  <span class=\"hljs-number\">699.99<\/span>\n         <span class=\"hljs-number\">10<\/span> | Apple AirPods Pro <span class=\"hljs-number\">3<\/span>       |           <span class=\"hljs-number\">5<\/span> |  <span class=\"hljs-number\">249.99<\/span>\n         <span class=\"hljs-number\">11<\/span> | Samsung Galaxy Buds Pro <span class=\"hljs-number\">2<\/span> |           <span class=\"hljs-number\">5<\/span> |  <span class=\"hljs-number\">199.99<\/span>\n         <span class=\"hljs-number\">12<\/span> | Apple Watch Series <span class=\"hljs-number\">9<\/span>      |           <span class=\"hljs-number\">6<\/span> |  <span class=\"hljs-number\">399.99<\/span>\n         <span class=\"hljs-number\">13<\/span> | Samsung Galaxy Watch <span class=\"hljs-number\">6<\/span>    |           <span class=\"hljs-number\">6<\/span> |  <span class=\"hljs-number\">349.99<\/span>\n...<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-14\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">PostgreSQL SQL dialect and PL\/pgSQL<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">pgsql<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p>You can get the category name by joining the CTE with the <code>categories<\/code> table:<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"415\" height=\"254\" src=\"https:\/\/www.pgtutorial.com\/wp-content\/uploads\/2024\/12\/products-categories-1.png\" alt=\"PostgreSQL ROW_NUMBER Window Function - Sample Tables\" class=\"wp-image-1049\" srcset=\"https:\/\/www.pgtutorial.com\/wp-content\/uploads\/2024\/12\/products-categories-1.png 415w, https:\/\/www.pgtutorial.com\/wp-content\/uploads\/2024\/12\/products-categories-1-300x184.png 300w\" sizes=\"auto, (max-width: 415px) 100vw, 415px\" \/><\/figure>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-15\" data-shcb-language-name=\"PostgreSQL SQL dialect and PL\/pgSQL\" data-shcb-language-slug=\"pgsql\"><span><code class=\"hljs language-pgsql\"><span class=\"hljs-keyword\">WITH<\/span> ranked_products <span class=\"hljs-keyword\">AS<\/span> (\n    <span class=\"hljs-keyword\">SELECT<\/span>\n      product_id,\n      product_name,\n      category_id,\n      price,\n      ROW_NUMBER() <span class=\"hljs-keyword\">OVER<\/span> (\n        <span class=\"hljs-keyword\">PARTITION<\/span> <span class=\"hljs-keyword\">BY<\/span>\n          category_id\n        <span class=\"hljs-keyword\">ORDER<\/span> <span class=\"hljs-keyword\">BY<\/span>\n          price <span class=\"hljs-keyword\">DESC<\/span>\n      ) <span class=\"hljs-keyword\">AS<\/span> rank\n    <span class=\"hljs-keyword\">FROM<\/span>\n      products\n  )\n<span class=\"hljs-keyword\">SELECT<\/span>\n  product_id,\n  product_name,\n  category_name,\n  price\n<span class=\"hljs-keyword\">FROM<\/span>\n  ranked_products\n  <span class=\"hljs-keyword\">JOIN<\/span> categories <span class=\"hljs-keyword\">USING<\/span> (category_id)\n<span class=\"hljs-keyword\">WHERE<\/span>\n  rank &lt;= <span class=\"hljs-number\">2<\/span>;<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-15\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">PostgreSQL SQL dialect and PL\/pgSQL<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">pgsql<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p><a href=\"https:\/\/www.pgtutorial.com\/playground\/?q=V0lUSCByYW5rZWRfcHJvZHVjdHMgQVMgKCBTRUxFQ1QgcHJvZHVjdF9pZCwgcHJvZHVjdF9uYW1lLCBjYXRlZ29yeV9pZCwgcHJpY2UsIFJPV19OVU1CRVIoKSBPVkVSICggUEFSVElUSU9OIEJZIGNhdGVnb3J5X2lkIE9SREVSIEJZIHByaWNlIERFU0MgKSBBUyByYW5rIEZST00gcHJvZHVjdHMgKSBTRUxFQ1QgcHJvZHVjdF9pZCwgcHJvZHVjdF9uYW1lLCBjYXRlZ29yeV9uYW1lLCBwcmljZSBGUk9NIHJhbmtlZF9wcm9kdWN0cyBKT0lOIGNhdGVnb3JpZXMgVVNJTkcgKGNhdGVnb3J5X2lkKSBXSEVSRSByYW5rIDw9IDI7\" target=\"_blank\" rel=\"noreferrer noopener\">Try it<\/a><\/p>\n\n\n\n<p>Output:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-16\" data-shcb-language-name=\"PostgreSQL SQL dialect and PL\/pgSQL\" data-shcb-language-slug=\"pgsql\"><span><code class=\"hljs language-pgsql\"> product_id |       product_name        | category_name |  price\n<span class=\"hljs-comment\">------------+---------------------------+---------------+---------<\/span>\n          <span class=\"hljs-number\">6<\/span> | Samsung Galaxy Z Fold <span class=\"hljs-number\">5<\/span>   | Smartphones   | <span class=\"hljs-number\">1799.99<\/span>\n          <span class=\"hljs-number\">7<\/span> | Apple iPhone <span class=\"hljs-number\">15<\/span> Pro Max   | Smartphones   | <span class=\"hljs-number\">1299.99<\/span>\n          <span class=\"hljs-number\">9<\/span> | Apple iPad Pro <span class=\"hljs-number\">12.9<\/span>       | Tablets       | <span class=\"hljs-number\">1099.99<\/span>\n          <span class=\"hljs-number\">8<\/span> | Samsung Galaxy Tab S9     | Tablets       |  <span class=\"hljs-number\">699.99<\/span>\n         <span class=\"hljs-number\">10<\/span> | Apple AirPods Pro <span class=\"hljs-number\">3<\/span>       | Accessories   |  <span class=\"hljs-number\">249.99<\/span>\n         <span class=\"hljs-number\">11<\/span> | Samsung Galaxy Buds Pro <span class=\"hljs-number\">2<\/span> | Accessories   |  <span class=\"hljs-number\">199.99<\/span>\n         <span class=\"hljs-number\">12<\/span> | Apple Watch Series <span class=\"hljs-number\">9<\/span>      | Wearables     |  <span class=\"hljs-number\">399.99<\/span>\n         <span class=\"hljs-number\">13<\/span> | Samsung Galaxy Watch <span class=\"hljs-number\">6<\/span>    | Wearables     |  <span class=\"hljs-number\">349.99<\/span>\n...<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-16\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">PostgreSQL SQL dialect and PL\/pgSQL<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">pgsql<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<h3 class=\"wp-block-heading\" id='removing-duplicate-rows'>Removing duplicate rows <a href=\"#removing-duplicate-rows\" class=\"anchor\" id=\"removing-duplicate-rows\" title=\"Anchor for Removing duplicate rows\">#<\/a><\/h3>\n\n\n\n<p>First, <a href=\"https:\/\/www.pgtutorial.com\/postgresql-tutorial\/postgresql-create-table\/\">create a table<\/a> called <code>items<\/code> with two columns <code>id<\/code> and <code>name<\/code>:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-17\" data-shcb-language-name=\"PostgreSQL SQL dialect and PL\/pgSQL\" data-shcb-language-slug=\"pgsql\"><span><code class=\"hljs language-pgsql\"><span class=\"hljs-keyword\">CREATE<\/span> <span class=\"hljs-keyword\">TABLE<\/span> items (\n   id <span class=\"hljs-type\">INT<\/span>, \n   <span class=\"hljs-type\">name<\/span> <span class=\"hljs-type\">VARCHAR<\/span>\n);<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-17\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">PostgreSQL SQL dialect and PL\/pgSQL<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">pgsql<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p>Second, <a href=\"https:\/\/www.pgtutorial.com\/postgresql-tutorial\/postgresql-insert\/\">insert rows<\/a> into the <code>items<\/code> table:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-18\" data-shcb-language-name=\"PostgreSQL SQL dialect and PL\/pgSQL\" data-shcb-language-slug=\"pgsql\"><span><code class=\"hljs language-pgsql\"><span class=\"hljs-keyword\">INSERT<\/span> <span class=\"hljs-keyword\">INTO<\/span>\n  items (id, <span class=\"hljs-type\">name<\/span>)\n<span class=\"hljs-keyword\">VALUES<\/span>\n  (<span class=\"hljs-number\">1<\/span>, <span class=\"hljs-string\">'iPhone'<\/span>),\n  (<span class=\"hljs-number\">2<\/span>, <span class=\"hljs-string\">'iPhone'<\/span>),\n  (<span class=\"hljs-number\">3<\/span>, <span class=\"hljs-string\">'Galaxy'<\/span>),\n  (<span class=\"hljs-number\">4<\/span>, <span class=\"hljs-string\">'Galaxy'<\/span>),\n  (<span class=\"hljs-number\">5<\/span>, <span class=\"hljs-string\">'iMac'<\/span>) \n<span class=\"hljs-keyword\">RETURNING<\/span> *;<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-18\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">PostgreSQL SQL dialect and PL\/pgSQL<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">pgsql<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p>Output:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-19\" data-shcb-language-name=\"PostgreSQL SQL dialect and PL\/pgSQL\" data-shcb-language-slug=\"pgsql\"><span><code class=\"hljs language-pgsql\"> id |  <span class=\"hljs-type\">name<\/span>\n<span class=\"hljs-comment\">----+--------<\/span>\n  <span class=\"hljs-number\">1<\/span> | iPhone\n  <span class=\"hljs-number\">2<\/span> | iPhone\n  <span class=\"hljs-number\">3<\/span> | Galaxy\n  <span class=\"hljs-number\">4<\/span> | Galaxy\n  <span class=\"hljs-number\">5<\/span> | iMac<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-19\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">PostgreSQL SQL dialect and PL\/pgSQL<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">pgsql<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p>The <code>items<\/code> table has duplicate values in the name columns with the id 2 and 4.<\/p>\n\n\n\n<p>Third, use the <code>ROW_NUMBER<\/code> function to divide the rows by name into partitions and assign each row in the partition a sequential integer:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-20\" data-shcb-language-name=\"PostgreSQL SQL dialect and PL\/pgSQL\" data-shcb-language-slug=\"pgsql\"><span><code class=\"hljs language-pgsql\"><span class=\"hljs-keyword\">SELECT<\/span>\n  id,\n  <span class=\"hljs-type\">name<\/span>,\n  ROW_NUMBER() <span class=\"hljs-keyword\">OVER<\/span> (\n    <span class=\"hljs-keyword\">PARTITION<\/span> <span class=\"hljs-keyword\">BY<\/span>\n      <span class=\"hljs-type\">name<\/span>\n    <span class=\"hljs-keyword\">ORDER<\/span> <span class=\"hljs-keyword\">BY<\/span>\n      id\n  ) <span class=\"hljs-keyword\">AS<\/span> row_number\n<span class=\"hljs-keyword\">FROM<\/span>\n  items\n<span class=\"hljs-keyword\">ORDER<\/span> <span class=\"hljs-keyword\">BY<\/span>\n  id;<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-20\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">PostgreSQL SQL dialect and PL\/pgSQL<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">pgsql<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p><a href=\"https:\/\/www.pgtutorial.com\/playground\/?db=row_number&amp;q=U0VMRUNUIGlkLCBuYW1lLCBST1dfTlVNQkVSKCkgT1ZFUiAoIFBBUlRJVElPTiBCWSBuYW1lIE9SREVSIEJZIGlkICkgQVMgcm93X251bWJlciBGUk9NIGl0ZW1zIE9SREVSIEJZIGlkOw%3D%3D\" target=\"_blank\" rel=\"noreferrer noopener\">Try it<\/a><\/p>\n\n\n\n<p>Output:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-21\" data-shcb-language-name=\"PostgreSQL SQL dialect and PL\/pgSQL\" data-shcb-language-slug=\"pgsql\"><span><code class=\"hljs language-pgsql\"> id |  <span class=\"hljs-type\">name<\/span>  | row_number\n<span class=\"hljs-comment\">----+--------+------------<\/span>\n  <span class=\"hljs-number\">1<\/span> | iPhone |          <span class=\"hljs-number\">1<\/span>\n  <span class=\"hljs-number\">2<\/span> | iPhone |          <span class=\"hljs-number\">2<\/span>\n  <span class=\"hljs-number\">3<\/span> | Galaxy |          <span class=\"hljs-number\">1<\/span>\n  <span class=\"hljs-number\">4<\/span> | Galaxy |          <span class=\"hljs-number\">2<\/span>\n  <span class=\"hljs-number\">5<\/span> | iMac   |          <span class=\"hljs-number\">1<\/span><\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-21\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">PostgreSQL SQL dialect and PL\/pgSQL<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">pgsql<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p>The duplicate rows are the ones that have the <code>row_number<\/code> greater than 1.<\/p>\n\n\n\n<p>You can delete these duplicate rows using a <a href=\"https:\/\/www.pgtutorial.com\/postgresql-tutorial\/postgresql-cte\/\">CTE<\/a> with a <code>DELETE<\/code> statement:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-22\" data-shcb-language-name=\"PostgreSQL SQL dialect and PL\/pgSQL\" data-shcb-language-slug=\"pgsql\"><span><code class=\"hljs language-pgsql\"><span class=\"hljs-keyword\">WITH<\/span> ranked_items <span class=\"hljs-keyword\">AS<\/span> (\n    <span class=\"hljs-keyword\">SELECT<\/span>\n      id,\n      <span class=\"hljs-type\">name<\/span>,\n      ROW_NUMBER() <span class=\"hljs-keyword\">OVER<\/span> (\n        <span class=\"hljs-keyword\">PARTITION<\/span> <span class=\"hljs-keyword\">BY<\/span>\n          <span class=\"hljs-type\">name<\/span>\n        <span class=\"hljs-keyword\">ORDER<\/span> <span class=\"hljs-keyword\">BY<\/span>\n          id\n      ) <span class=\"hljs-keyword\">AS<\/span> row_number\n    <span class=\"hljs-keyword\">FROM<\/span>\n      items\n  )\n<span class=\"hljs-keyword\">DELETE<\/span> <span class=\"hljs-keyword\">FROM<\/span> items\n<span class=\"hljs-keyword\">WHERE<\/span> id <span class=\"hljs-keyword\">IN<\/span> (\n    <span class=\"hljs-keyword\">SELECT<\/span>\n      id\n    <span class=\"hljs-keyword\">FROM<\/span>\n      ranked_items\n    <span class=\"hljs-keyword\">where<\/span>\n      row_number &gt; <span class=\"hljs-number\">1<\/span>\n  );<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-22\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">PostgreSQL SQL dialect and PL\/pgSQL<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">pgsql<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p><a href=\"https:\/\/www.pgtutorial.com\/playground\/?db=row_number&amp;q=V0lUSCByYW5rZWRfaXRlbXMgQVMgKCBTRUxFQ1QgaWQsIG5hbWUsIFJPV19OVU1CRVIoKSBPVkVSICggUEFSVElUSU9OIEJZIG5hbWUgT1JERVIgQlkgaWQgKSBBUyByb3dfbnVtYmVyIEZST00gaXRlbXMgKSBERUxFVEUgRlJPTSBpdGVtcyBXSEVSRSBpZCBJTiAoIFNFTEVDVCBpZCBGUk9NIHJhbmtlZF9pdGVtcyB3aGVyZSByb3dfbnVtYmVyID4gMSApOw%3D%3D\" target=\"_blank\" rel=\"noreferrer noopener\">Try it<\/a><\/p>\n\n\n\n<p>Finally, retrieve data from the <code>items<\/code> table to verify the removal:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-23\" data-shcb-language-name=\"PostgreSQL SQL dialect and PL\/pgSQL\" data-shcb-language-slug=\"pgsql\"><span><code class=\"hljs language-pgsql\"><span class=\"hljs-keyword\">SELECT<\/span>\n  id,\n  <span class=\"hljs-type\">name<\/span>\n<span class=\"hljs-keyword\">FROM<\/span>\n  items;<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-23\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">PostgreSQL SQL dialect and PL\/pgSQL<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">pgsql<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p><a href=\"https:\/\/www.pgtutorial.com\/playground\/?db=row_number&amp;q=U0VMRUNUIGlkLCBuYW1lIEZST00gaXRlbXM7\" target=\"_blank\" rel=\"noreferrer noopener\">Try it<\/a><\/p>\n\n\n\n<p>Output:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-24\" data-shcb-language-name=\"PostgreSQL SQL dialect and PL\/pgSQL\" data-shcb-language-slug=\"pgsql\"><span><code class=\"hljs language-pgsql\"> id |  <span class=\"hljs-type\">name<\/span>\n<span class=\"hljs-comment\">----+--------<\/span>\n  <span class=\"hljs-number\">1<\/span> | iPhone\n  <span class=\"hljs-number\">3<\/span> | Galaxy\n  <span class=\"hljs-number\">5<\/span> | iMac<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-24\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">PostgreSQL SQL dialect and PL\/pgSQL<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">pgsql<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<h2 class=\"wp-block-heading\" id='summary'>Summary <a href=\"#summary\" class=\"anchor\" id=\"summary\" title=\"Anchor for Summary\">#<\/a><\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Use the PostgreSQL <code>ROW_NUMBER()<\/code> window function to assign unique sequential integers to rows within a partition of a result set.<\/li>\n\n\n\n<li>Use the <code>ROW_NUMBER<\/code> function to rank rows, get top N records, and identify duplicate rows from a table.<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\" id='quiz'>Quiz <a href=\"#quiz\" class=\"anchor\" id=\"quiz\" title=\"Anchor for Quiz\">#<\/a><\/h2>\n\n\n\n<iframe loading=\"lazy\"\n  name=\"quiz\"\n  src=\"\/quiz\/?quiz=row_number\"\n  height=\"700\"\n  width=\"600\"\n  class=\"iframe\"\n><\/iframe>\n\n<div class=\"helpful-block-content\" data-title=\"\">\n\t<header>\n\t\t<div class=\"wth-question\">Was this tutorial helpful ?<\/div>\n\t\t<div class=\"wth-thumbs\">\n\t\t\t<button\n\t\t\t\tdata-post=\"1079\"\n\t\t\t\tdata-post-url=\"https:\/\/www.pgtutorial.com\/postgresql-window-functions\/postgresql-row_number\/\"\n\t\t\t\tdata-post-title=\"PostgreSQL ROW_NUMBER Window 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