{"id":1998,"date":"2025-02-11T10:18:29","date_gmt":"2025-02-11T03:18:29","guid":{"rendered":"https:\/\/www.pgtutorial.com\/?page_id=1998"},"modified":"2025-02-11T11:32:41","modified_gmt":"2025-02-11T04:32:41","slug":"postgresql-overlay","status":"publish","type":"page","link":"https:\/\/www.pgtutorial.com\/postgresql-string-functions\/postgresql-overlay\/","title":{"rendered":"PostgreSQL OVERLAY Function"},"content":{"rendered":"\n<p><strong>Summary<\/strong>: in this tutorial, you&#8217;ll learn how to use the PostgreSQL <code>OVERLAY<\/code> function to replace a substring specified by a position and length with a new substring.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\" id='introduction-to-the-postgresql-overlay-function'>Introduction to the PostgreSQL OVERLAY function <a href=\"#introduction-to-the-postgresql-overlay-function\" class=\"anchor\" id=\"introduction-to-the-postgresql-overlay-function\" title=\"Anchor for Introduction to the PostgreSQL OVERLAY function\">#<\/a><\/h2>\n\n\n\n<p>The <code>OVERLAY<\/code> function replaces a substring within a string with a new substring.<\/p>\n\n\n\n<p>Unlike the <code><a href=\"https:\/\/www.pgtutorial.com\/postgresql-string-functions\/postgresql-replace\/\">REPLACE<\/a><\/code> function, the <code>OVERLAY<\/code> function allows you to determine the starting position and length of the substring to be replaced.<\/p>\n\n\n\n<p>Here&#8217;s the syntax of the <code>OVERLAY<\/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\">OVERLAY(string <span class=\"hljs-keyword\">PLACING<\/span> new_substring <span class=\"hljs-keyword\">FROM<\/span> start_position &#91;<span class=\"hljs-keyword\">FOR<\/span> length])<\/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>The <code>OVERLAY<\/code> function takes four parameters:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><code>string<\/code>: the input string.<\/li>\n\n\n\n<li><code>new_substring<\/code>: the new substring you use for replacement in the input string.<\/li>\n\n\n\n<li><code>start_position<\/code>: the position in the original string where you want the replacement to begin. The <code>start_position<\/code>is a 1-based index, meaning that the first character has a position of 1.<\/li>\n\n\n\n<li><code>length<\/code>(optional) is the number of characters to replace in the input string. If you omit the length parameter, the function will use the length of the <code>new_substring<\/code>.<\/li>\n<\/ul>\n\n\n\n<p>The <code>OVERLAY<\/code> function returns a new string with a substring specified by a starting position and length replaced by the new substring.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\" id='basic-postgresql-overlay-function-examples'>Basic PostgreSQL OVERLAY function examples <a href=\"#basic-postgresql-overlay-function-examples\" class=\"anchor\" id=\"basic-postgresql-overlay-function-examples\" title=\"Anchor for Basic PostgreSQL OVERLAY function examples\">#<\/a><\/h2>\n\n\n\n<p>The following statement uses the <code>OVERLAY<\/code> function to replace a substring in the string <code>'Hello World'<\/code> starting from position <code>7<\/code>:<\/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  OVERLAY(\n    <span class=\"hljs-string\">'123456789'<\/span> <span class=\"hljs-keyword\">PLACING<\/span> <span class=\"hljs-string\">'abc'<\/span>\n    <span class=\"hljs-keyword\">FROM<\/span>\n      <span class=\"hljs-number\">4<\/span>\n  ) result;<\/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=U0VMRUNUIE9WRVJMQVkoICcxMjM0NTY3ODknIFBMQUNJTkcgJ2FiYycgRlJPTSA0ICkgcmVzdWx0Ow%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-3\" data-shcb-language-name=\"PostgreSQL SQL dialect and PL\/pgSQL\" data-shcb-language-slug=\"pgsql\"><span><code class=\"hljs language-pgsql\">  result\n<span class=\"hljs-comment\">-----------<\/span>\n <span class=\"hljs-number\">123<\/span>abc789<\/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 4<\/code> returns a substring starting from position four.<\/li>\n\n\n\n<li>The <code>length<\/code> defaults to the new substring&#8217;s length (<code>'abc'<\/code>), which is 3.<\/li>\n\n\n\n<li>The function substitutes three characters in the input string with the substring <code>'abc'<\/code>, which returns <code>'123abc789'<\/code>.<\/li>\n<\/ul>\n\n\n\n<p>If you want to replace only a specific number of characters, you can use the <code>FOR<\/code> clause:<\/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  OVERLAY(\n    <span class=\"hljs-string\">'123456789'<\/span> <span class=\"hljs-keyword\">PLACING<\/span> <span class=\"hljs-string\">'abc'<\/span>\n    <span class=\"hljs-keyword\">FROM<\/span>\n      <span class=\"hljs-number\">4<\/span> <span class=\"hljs-keyword\">FOR<\/span> <span class=\"hljs-number\">5<\/span>\n  ) result;<\/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=U0VMRUNUIE9WRVJMQVkoICcxMjM0NTY3ODknIFBMQUNJTkcgJ2FiYycgRlJPTSA0IEZPUiA1ICkgcmVzdWx0Ow%3D%3D\" target=\"_blank\" rel=\"noreferrer noopener\">Try it<\/a><\/p>\n\n\n\n<p>In this example:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>The <code>FROM 4 FOR 5<\/code> returns the substring <code>'45678'<\/code>.<\/li>\n\n\n\n<li>The <code>OVERLAY<\/code> function replaces substring <code>'45678'<\/code> with the substring <code>'abc'<\/code> .<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\" id='masking-data'>Masking data <a href=\"#masking-data\" class=\"anchor\" id=\"masking-data\" title=\"Anchor for Masking data\">#<\/a><\/h2>\n\n\n\n<p>The <code>OVERLAY<\/code> function can be helpful for data masking. For example, the following query uses the <code>OVERLAY<\/code> function to show only the last four digits of the home phones of the users:<\/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\"><span class=\"hljs-keyword\">SELECT<\/span>\n  first_name,\n  home_phone,\n  OVERLAY(\n    home_phone <span class=\"hljs-keyword\">PLACING<\/span> <span class=\"hljs-string\">'***'<\/span>\n    <span class=\"hljs-keyword\">FROM<\/span> <span class=\"hljs-number\">5<\/span>\n  ) masked_home_phone\n<span class=\"hljs-keyword\">FROM<\/span>\n  profiles;<\/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><a href=\"https:\/\/www.pgtutorial.com\/playground\/?q=U0VMRUNUIGZpcnN0X25hbWUsIGhvbWVfcGhvbmUsIE9WRVJMQVkoIGhvbWVfcGhvbmUgUExBQ0lORyAnKioqJyBGUk9NIDUgKSBtYXNrZWRfaG9tZV9waG9uZSBGUk9NIHByb2ZpbGVzOw%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-6\" data-shcb-language-name=\"PostgreSQL SQL dialect and PL\/pgSQL\" data-shcb-language-slug=\"pgsql\"><span><code class=\"hljs language-pgsql\"> first_name |  home_phone  | masked_home_phone\n<span class=\"hljs-comment\">------------+--------------+-------------------<\/span>\n John       | <span class=\"hljs-number\">408<\/span><span class=\"hljs-number\">-111<\/span><span class=\"hljs-number\">-2222<\/span> | <span class=\"hljs-number\">408<\/span>-***<span class=\"hljs-number\">-2222<\/span>\n Jane       | <span class=\"hljs-number\">408<\/span><span class=\"hljs-number\">-111<\/span><span class=\"hljs-number\">-3333<\/span> | <span class=\"hljs-number\">408<\/span>-***<span class=\"hljs-number\">-3333<\/span>\n Alice      | <span class=\"hljs-number\">408<\/span><span class=\"hljs-number\">-111<\/span><span class=\"hljs-number\">-4444<\/span> | <span class=\"hljs-number\">408<\/span>-***<span class=\"hljs-number\">-4444<\/span>\n Bob        | <span class=\"hljs-number\">408<\/span><span class=\"hljs-number\">-111<\/span><span class=\"hljs-number\">-5555<\/span> | <span class=\"hljs-number\">408<\/span>-***<span class=\"hljs-number\">-5555<\/span>\n Charlie    | <span class=\"hljs-keyword\">NULL<\/span>         | <span class=\"hljs-keyword\">NULL<\/span><\/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<h2 class=\"wp-block-heading\" id='edge-cases'>Edge cases <a href=\"#edge-cases\" class=\"anchor\" id=\"edge-cases\" title=\"Anchor for Edge cases\">#<\/a><\/h2>\n\n\n\n<h3 class=\"wp-block-heading\" id='case-1-negative-starting-position'>Case 1: Negative starting position <a href=\"#case-1-negative-starting-position\" class=\"anchor\" id=\"case-1-negative-starting-position\" title=\"Anchor for Case 1: Negative starting position\">#<\/a><\/h3>\n\n\n\n<p>If the starting position is zero or negative, the <code>OVERLAY<\/code> function issues an error:<\/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\"><span class=\"hljs-keyword\">SELECT<\/span>\n  OVERLAY(\n    <span class=\"hljs-string\">'123456789'<\/span> <span class=\"hljs-keyword\">PLACING<\/span> <span class=\"hljs-string\">'abc'<\/span>\n    <span class=\"hljs-keyword\">FROM<\/span>\n      <span class=\"hljs-number\">-1<\/span>\n  ) result;<\/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><a href=\"https:\/\/www.pgtutorial.com\/playground\/?q=U0VMRUNUIE9WRVJMQVkoICcxMjM0NTY3ODknIFBMQUNJTkcgJ2FiYycgRlJPTSAtMSApIHJlc3VsdDs%3D\" target=\"_blank\" rel=\"noreferrer noopener\">Try it<\/a><\/p>\n\n\n\n<p>Error:<\/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\">ERROR: negative substring length <span class=\"hljs-keyword\">not<\/span> allowed<\/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<h3 class=\"wp-block-heading\" id='case-2-the-starting-position-exceeds-the-length-of-the-input-string'>Case 2: The starting position exceeds the length of the input string <a href=\"#case-2-the-starting-position-exceeds-the-length-of-the-input-string\" class=\"anchor\" id=\"case-2-the-starting-position-exceeds-the-length-of-the-input-string\" title=\"Anchor for Case 2: The starting position exceeds the length of the input string\">#<\/a><\/h3>\n\n\n\n<p>If the starting position exceeds the length of the input string, the <code>OVERLAY<\/code> function concatenates the input string with the substring:<\/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\"><span class=\"hljs-keyword\">SELECT<\/span>\n  OVERLAY(\n    <span class=\"hljs-string\">'123456789'<\/span> <span class=\"hljs-keyword\">PLACING<\/span> <span class=\"hljs-string\">'abc'<\/span>\n    <span class=\"hljs-keyword\">FROM<\/span>\n      <span class=\"hljs-number\">10<\/span>\n  ) result;<\/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><a href=\"https:\/\/www.pgtutorial.com\/playground\/?q=U0VMRUNUIE9WRVJMQVkoICcxMjM0NTY3ODknIFBMQUNJTkcgJ2FiYycgRlJPTSAxMCApIHJlc3VsdDs%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-10\" data-shcb-language-name=\"PostgreSQL SQL dialect and PL\/pgSQL\" data-shcb-language-slug=\"pgsql\"><span><code class=\"hljs language-pgsql\">    result\n<span class=\"hljs-comment\">--------------<\/span>\n <span class=\"hljs-number\">123456789<\/span>abc<\/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<h3 class=\"wp-block-heading\" id='case-3-zero-or-negative-length'>Case 3: Zero or negative length <a href=\"#case-3-zero-or-negative-length\" class=\"anchor\" id=\"case-3-zero-or-negative-length\" title=\"Anchor for Case 3: Zero or negative length\">#<\/a><\/h3>\n\n\n\n<p>If the length is zero or negative, the <code>OVERLAY<\/code> function inserts the new substring at the starting position into the input string:<\/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\"><span class=\"hljs-keyword\">SELECT<\/span>\n  OVERLAY(\n    <span class=\"hljs-string\">'123456789'<\/span> <span class=\"hljs-keyword\">PLACING<\/span> <span class=\"hljs-string\">'abc'<\/span>\n    <span class=\"hljs-keyword\">FROM<\/span>\n      <span class=\"hljs-number\">3<\/span> <span class=\"hljs-keyword\">FOR<\/span> <span class=\"hljs-number\">0<\/span>\n  ) result;<\/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><a href=\"https:\/\/www.pgtutorial.com\/playground\/?q=U0VMRUNUIE9WRVJMQVkoICcxMjM0NTY3ODknIFBMQUNJTkcgJ2FiYycgRlJPTSAzIEZPUiAwICkgcmVzdWx0Ow%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-12\" data-shcb-language-name=\"PostgreSQL SQL dialect and PL\/pgSQL\" data-shcb-language-slug=\"pgsql\"><span><code class=\"hljs language-pgsql\">    result\n<span class=\"hljs-comment\">--------------<\/span>\n <span class=\"hljs-number\">12<\/span>abc3456789\n(<span class=\"hljs-number\">1<\/span> <span class=\"hljs-keyword\">row<\/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='case-4-null-arguments'>Case 4. NULL arguments <a href=\"#case-4-null-arguments\" class=\"anchor\" id=\"case-4-null-arguments\" title=\"Anchor for Case 4. NULL arguments\">#<\/a><\/h3>\n\n\n\n<p>The function returns <code>NULL<\/code> if any argument is <code>NULL<\/code>:<\/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\">SELECT<\/span>\n  OVERLAY(\n    <span class=\"hljs-string\">'123456789'<\/span> <span class=\"hljs-keyword\">PLACING<\/span> <span class=\"hljs-string\">'abc'<\/span>\n    <span class=\"hljs-keyword\">FROM<\/span>\n      <span class=\"hljs-keyword\">NULL<\/span> <span class=\"hljs-keyword\">FOR<\/span> <span class=\"hljs-number\">0<\/span>\n  ) result;<\/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=U0VMRUNUIE9WRVJMQVkoICcxMjM0NTY3ODknIFBMQUNJTkcgJ2FiYycgRlJPTSBOVUxMIEZPUiAwICkgcmVzdWx0Ow%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\"> result\n<span class=\"hljs-comment\">--------<\/span>\n <span class=\"hljs-keyword\">NULL<\/span>\n(<span class=\"hljs-number\">1<\/span> <span class=\"hljs-keyword\">row<\/span>)<\/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<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 <code>OVERLAY<\/code> function to replace a substring specified by a position and length with a new substring.<\/li>\n<\/ul>\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=\"1998\"\n\t\t\t\tdata-post-url=\"https:\/\/www.pgtutorial.com\/postgresql-string-functions\/postgresql-overlay\/\"\n\t\t\t\tdata-post-title=\"PostgreSQL OVERLAY Function\"\n\t\t\t\tdata-response=\"1\"\n\t\t\t\tclass=\"wth-btn-rounded 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with a new substring.<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":1800,"menu_order":20,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-1998","page","type-page","status-publish","hentry"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v27.5 - https:\/\/yoast.com\/product\/yoast-seo-wordpress\/ -->\n<title>PostgreSQL OVERLAY Function<\/title>\n<meta name=\"description\" content=\"You&#039;ll learn how to use the PostgreSQL OVERLAY function to replace a substring specified by a position and length with a new substring.\" \/>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.pgtutorial.com\/postgresql-string-functions\/postgresql-overlay\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" 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