{"id":562,"date":"2024-12-02T11:16:46","date_gmt":"2024-12-02T04:16:46","guid":{"rendered":"https:\/\/www.pgtutorial.com\/?page_id=562"},"modified":"2025-01-02T13:46:43","modified_gmt":"2025-01-02T06:46:43","slug":"postgresql-decimal","status":"publish","type":"page","link":"https:\/\/www.pgtutorial.com\/postgresql-tutorial\/postgresql-decimal\/","title":{"rendered":"PostgreSQL DECIMAL Data Type"},"content":{"rendered":"\n<p><strong>Summary<\/strong>: in this tutorial, you&#8217;ll learn how to use the PostgreSQL <code>DECIMAL<\/code> data type to store the exact numeric data in the database.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\" id='getting-started-with-postgresql-decimal-data-type'>Getting started with PostgreSQL DECIMAL data type <a href=\"#getting-started-with-postgresql-decimal-data-type\" class=\"anchor\" id=\"getting-started-with-postgresql-decimal-data-type\" title=\"Anchor for Getting started with PostgreSQL DECIMAL data type\">#<\/a><\/h2>\n\n\n\n<p>PostgreSQL <code>DECIMAL<\/code> is a numeric data type that allows you to store exact numeric values with precision.<\/p>\n\n\n\n<p>The <code>DECIMAL<\/code> data type, with its precision and exactness, is suitable for storing financial amounts and other numbers where accuracy is crucial.<\/p>\n\n\n\n<p>Here&#8217;s the syntax for the defining a <code>DECIMAL<\/code> column:<\/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\"><span class=\"hljs-keyword\">CREATE<\/span> <span class=\"hljs-keyword\">TABLE<\/span> <span class=\"hljs-built_in\">table_name<\/span>(\n\u00a0 \u00a0 \u00a0<span class=\"hljs-built_in\">column_name<\/span> <span class=\"hljs-type\">DECIMAL<\/span>(p,s),\n\u00a0 \u00a0 \u00a0...\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><code>DEC<\/code>and <code>NUMERIC<\/code> are synonyms of the <code>DECIMAL<\/code>, so you can use them interchangeably. For example:<\/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\">CREATE<\/span> <span class=\"hljs-keyword\">TABLE<\/span> <span class=\"hljs-built_in\">table_name<\/span>(\n\u00a0 \u00a0 \u00a0<span class=\"hljs-built_in\">column_name<\/span> <span class=\"hljs-type\">DEC<\/span>(p,s),\n\u00a0 \u00a0 \u00a0...\n);<\/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>In this syntax:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><code>p<\/code> stands for <em>precision<\/em>. The precision is the number of significant digits, including integer and fractional parts. The precision must be between <code>1<\/code> and <code>1000<\/code>.<\/li>\n\n\n\n<li><code>s<\/code> stands for <em>scale<\/em>. The scale is the number of digits to the right of the decimal point. The valid range for scale is from <code>-1000<\/code> to <code>1000<\/code>. More on the negative scale soon.<\/li>\n<\/ul>\n\n\n\n<p>For example, a <code>DEC(11,2)<\/code> column can store a number with 11 digits, including two digits after the decimal point.<\/p>\n\n\n\n<p>If you omit the scale, it will default to zero:<\/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\"><span class=\"hljs-type\">DEC<\/span>(p)<\/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>It is equivalent to:<\/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-type\">DEC<\/span>(p,<span class=\"hljs-number\">0<\/span>)<\/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>However, the precision and scale will default to their above limits if you ignore both precision and scale:<\/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-type\">DEC<\/span><\/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>If you don&#8217;t use precision and scale constraints, PostgreSQL can store up to <code>131072<\/code> digits before and up to <code>16383<\/code> digits after the decimal point.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\" id='postgresql-decimal-data-type-example'>PostgreSQL Decimal Data Type example <a href=\"#postgresql-decimal-data-type-example\" class=\"anchor\" id=\"postgresql-decimal-data-type-example\" title=\"Anchor for PostgreSQL Decimal Data Type example\">#<\/a><\/h2>\n\n\n\n<p>First, <a href=\"https:\/\/www.pgtutorial.com\/postgresql-tutorial\/postgresql-create-table\/\">create a table<\/a> called <code>inventories<\/code>:<\/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\">CREATE<\/span> <span class=\"hljs-keyword\">TABLE<\/span> inventories (\n  id <span class=\"hljs-type\">INT<\/span> <span class=\"hljs-keyword\">GENERATED<\/span> <span class=\"hljs-keyword\">ALWAYS<\/span> <span class=\"hljs-keyword\">AS<\/span> <span class=\"hljs-keyword\">IDENTITY<\/span> <span class=\"hljs-keyword\">PRIMARY KEY<\/span>,\n  product_name <span class=\"hljs-type\">VARCHAR<\/span>(<span class=\"hljs-number\">255<\/span>) <span class=\"hljs-keyword\">NOT<\/span> <span class=\"hljs-keyword\">NULL<\/span>,\n  quantity <span class=\"hljs-type\">INT<\/span> <span class=\"hljs-keyword\">NOT<\/span> <span class=\"hljs-keyword\">NULL<\/span> <span class=\"hljs-keyword\">CHECK<\/span> (quantity &gt;= <span class=\"hljs-number\">0<\/span>),\n  price <span class=\"hljs-type\">DEC<\/span>(<span class=\"hljs-number\">11<\/span>, <span class=\"hljs-number\">2<\/span>) <span class=\"hljs-keyword\">NOT<\/span> <span class=\"hljs-keyword\">NULL<\/span> <span class=\"hljs-keyword\">CHECK<\/span> (price &gt; <span class=\"hljs-number\">0<\/span>),\n  brand <span class=\"hljs-type\">VARCHAR<\/span>(<span class=\"hljs-number\">255<\/span>) <span class=\"hljs-keyword\">NOT<\/span> <span class=\"hljs-keyword\">NULL<\/span>\n);<\/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>Second, <a href=\"https:\/\/www.pgtutorial.com\/postgresql-tutorial\/postgresql-insert\/\">insert some rows<\/a> into the <code>inventories<\/code> table:<\/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\">INSERT<\/span> <span class=\"hljs-keyword\">INTO<\/span>\n  inventories (product_name, quantity, price, brand)\n<span class=\"hljs-keyword\">VALUES<\/span>\n  (<span class=\"hljs-string\">'iPhone 16 Pro'<\/span>, <span class=\"hljs-number\">50<\/span>, <span class=\"hljs-number\">999.99<\/span>, <span class=\"hljs-string\">'Apple'<\/span>),\n  (<span class=\"hljs-string\">'iPhone 16 Pro Max'<\/span>, <span class=\"hljs-number\">40<\/span>, <span class=\"hljs-number\">1099.99<\/span>, <span class=\"hljs-string\">'Apple'<\/span>),\n  (<span class=\"hljs-string\">'iPhone 16 Plus'<\/span>, <span class=\"hljs-number\">55<\/span>, <span class=\"hljs-number\">899.99<\/span>, <span class=\"hljs-string\">'Apple'<\/span>),\n  (<span class=\"hljs-string\">'Galaxy S24 Ultra'<\/span>, <span class=\"hljs-number\">45<\/span>, <span class=\"hljs-number\">1199.99<\/span>, <span class=\"hljs-string\">'Samsung'<\/span>),\n  (<span class=\"hljs-string\">'Galaxy S24 Plus'<\/span>, <span class=\"hljs-number\">50<\/span>, <span class=\"hljs-number\">999.99<\/span>, <span class=\"hljs-string\">'Samsung'<\/span>),\n  (<span class=\"hljs-string\">'Galaxy Z Fold 6'<\/span>, <span class=\"hljs-number\">30<\/span>, <span class=\"hljs-number\">1799.99<\/span>, <span class=\"hljs-string\">'Samsung'<\/span>),\n  (<span class=\"hljs-string\">'Galaxy Z Flip 6'<\/span>, <span class=\"hljs-number\">35<\/span>, <span class=\"hljs-number\">999.99<\/span>, <span class=\"hljs-string\">'Samsung'<\/span>),\n  (<span class=\"hljs-string\">'Pixel 9'<\/span>, <span class=\"hljs-number\">50<\/span>, <span class=\"hljs-number\">799.99<\/span>, <span class=\"hljs-string\">'Google'<\/span>),\n  (<span class=\"hljs-string\">'Pixel 9 Pro'<\/span>, <span class=\"hljs-number\">40<\/span>, <span class=\"hljs-number\">999.99<\/span>, <span class=\"hljs-string\">'Google'<\/span>),\n  (<span class=\"hljs-string\">'Pixel 9 Pro Fold'<\/span>, <span class=\"hljs-number\">25<\/span>, <span class=\"hljs-number\">1799.99<\/span>, <span class=\"hljs-string\">'Google'<\/span>)\n<span class=\"hljs-keyword\">RETURNING<\/span> *;<\/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>Output:<\/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\"> id |   product_name    | quantity |  price  |  brand\n<span class=\"hljs-comment\">----+-------------------+----------+---------+---------<\/span>\n  <span class=\"hljs-number\">1<\/span> | iPhone <span class=\"hljs-number\">16<\/span> Pro     |       <span class=\"hljs-number\">50<\/span> |  <span class=\"hljs-number\">999.99<\/span> | Apple\n  <span class=\"hljs-number\">2<\/span> | iPhone <span class=\"hljs-number\">16<\/span> Pro Max |       <span class=\"hljs-number\">40<\/span> | <span class=\"hljs-number\">1099.99<\/span> | Apple\n  <span class=\"hljs-number\">3<\/span> | iPhone <span class=\"hljs-number\">16<\/span> Plus    |       <span class=\"hljs-number\">55<\/span> |  <span class=\"hljs-number\">899.99<\/span> | Apple\n  <span class=\"hljs-number\">4<\/span> | Galaxy S24 Ultra  |       <span class=\"hljs-number\">45<\/span> | <span class=\"hljs-number\">1199.99<\/span> | Samsung\n  <span class=\"hljs-number\">5<\/span> | Galaxy S24 Plus   |       <span class=\"hljs-number\">50<\/span> |  <span class=\"hljs-number\">999.99<\/span> | Samsung\n  <span class=\"hljs-number\">6<\/span> | Galaxy Z Fold <span class=\"hljs-number\">6<\/span>   |       <span class=\"hljs-number\">30<\/span> | <span class=\"hljs-number\">1799.99<\/span> | Samsung\n  <span class=\"hljs-number\">7<\/span> | Galaxy Z Flip <span class=\"hljs-number\">6<\/span>   |       <span class=\"hljs-number\">35<\/span> |  <span class=\"hljs-number\">999.99<\/span> | Samsung\n  <span class=\"hljs-number\">8<\/span> | Pixel <span class=\"hljs-number\">9<\/span>           |       <span class=\"hljs-number\">50<\/span> |  <span class=\"hljs-number\">799.99<\/span> | Google\n  <span class=\"hljs-number\">9<\/span> | Pixel <span class=\"hljs-number\">9<\/span> Pro       |       <span class=\"hljs-number\">40<\/span> |  <span class=\"hljs-number\">999.99<\/span> | Google\n <span class=\"hljs-number\">10<\/span> | Pixel <span class=\"hljs-number\">9<\/span> Pro Fold  |       <span class=\"hljs-number\">25<\/span> | <span class=\"hljs-number\">1799.99<\/span> | Google<\/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>Third, calculate the total inventory value for each brand:<\/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  brand,\n  SUM(quantity * price)\n<span class=\"hljs-keyword\">FROM<\/span>\n  inventories\n<span class=\"hljs-keyword\">GROUP<\/span> <span class=\"hljs-keyword\">BY<\/span>\n  brand;<\/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>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\">  brand  |    sum\n<span class=\"hljs-comment\">---------+-----------<\/span>\n Google  | <span class=\"hljs-number\">124998.85<\/span>\n Apple   | <span class=\"hljs-number\">143498.55<\/span>\n Samsung | <span class=\"hljs-number\">192998.40<\/span><\/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<h2 class=\"wp-block-heading\" id='negative-scales'>Negative scales <a href=\"#negative-scales\" class=\"anchor\" id=\"negative-scales\" title=\"Anchor for Negative scales\">#<\/a><\/h2>\n\n\n\n<p>Starting from PostgreSQL 15, you can declare a decimal column with a negative scale:<\/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-type\">DEC<\/span>(p,-s)<\/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>In this syntax, PostgreSQL will round the number to the left of the decimal point. The precision (p) represents the maximum number of non-rounded digits.<\/p>\n\n\n\n<p>For example:<\/p>\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 a <code>DEC<\/code> column that has a negative scale:<\/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\">CREATE<\/span> <span class=\"hljs-keyword\">TABLE<\/span> items (\n  item_id <span class=\"hljs-type\">INT<\/span> <span class=\"hljs-keyword\">GENERATED<\/span> <span class=\"hljs-keyword\">ALWAYS<\/span> <span class=\"hljs-keyword\">AS<\/span> <span class=\"hljs-keyword\">IDENTITY<\/span> <span class=\"hljs-keyword\">PRIMARY KEY<\/span>,\n  <span class=\"hljs-keyword\">value<\/span> <span class=\"hljs-type\">DEC<\/span>(<span class=\"hljs-number\">5<\/span>, <span class=\"hljs-number\">-2<\/span>) <span class=\"hljs-keyword\">NOT<\/span> <span class=\"hljs-keyword\">NULL<\/span>\n);<\/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<p>Second, insert two rows into the <code>items<\/code> table:<\/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\">INSERT<\/span> <span class=\"hljs-keyword\">INTO<\/span>\n  items (<span class=\"hljs-keyword\">value<\/span>)\n<span class=\"hljs-keyword\">VALUES<\/span>\n  (<span class=\"hljs-number\">12345<\/span>),\n  (<span class=\"hljs-number\">67890<\/span>) \n<span class=\"hljs-keyword\">RETURNING<\/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>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\"> item_id | <span class=\"hljs-keyword\">value<\/span>\n<span class=\"hljs-comment\">---------+-------<\/span>\n       <span class=\"hljs-number\">1<\/span> | <span class=\"hljs-number\">12300<\/span>\n       <span class=\"hljs-number\">2<\/span> | <span class=\"hljs-number\">67900<\/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<p>Since the <code>value<\/code> column has a precision of <code>-2<\/code>, PostgreSQL rounds them to the nearest hundred, with the total number of significant digits being 5.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\" id='rounding'>Rounding <a href=\"#rounding\" class=\"anchor\" id=\"rounding\" title=\"Anchor for Rounding\">#<\/a><\/h2>\n\n\n\n<p>PostgreSQL uses the round ties away from zeros for decimal values.<\/p>\n\n\n\n<p>For example, if you round 2.5 to the nearest whole number, PostgreSQL will round it to 3. If you round -2.5 to the nearest number, PostgreSQL will round it to -3.<\/p>\n\n\n\n<p>The following example shows how to use the <code>ROUND<\/code> function to round the average inventory values to numbers with two digits after the decimal point:<\/p>\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\">SELECT<\/span>\n  brand,\n  AVG(quantity * price),\n  ROUND(AVG(quantity * price), <span class=\"hljs-number\">2<\/span>)\n<span class=\"hljs-keyword\">FROM<\/span>\n  inventories\n<span class=\"hljs-keyword\">GROUP<\/span> <span class=\"hljs-keyword\">BY<\/span>\n  brand;<\/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>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\">  brand  |        avg         |  round\n<span class=\"hljs-comment\">---------+--------------------+----------<\/span>\n Google  | <span class=\"hljs-number\">41666.283333333333<\/span> | <span class=\"hljs-number\">41666.28<\/span>\n Apple   | <span class=\"hljs-number\">47832.850000000000<\/span> | <span class=\"hljs-number\">47832.85<\/span>\n Samsung | <span class=\"hljs-number\">48249.600000000000<\/span> | <span class=\"hljs-number\">48249.60<\/span><\/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<h2 class=\"wp-block-heading\" id='special-values'>Special values <a href=\"#special-values\" class=\"anchor\" id=\"special-values\" title=\"Anchor for Special values\">#<\/a><\/h2>\n\n\n\n<p>Besides regular values, the decimal type supports several special values specified in the IEEE 754 standard:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><code>Infinity<\/code>&#8211; represents an infinitely large value.<\/li>\n\n\n\n<li><code>-Infinity<\/code> &#8211; represents an infinitely small value.<\/li>\n\n\n\n<li><code>NaN<\/code> (not-a-number) &#8211; represents a value that is not a number, which results from an invalid calculation.<\/li>\n<\/ul>\n\n\n\n<p>When using these values in SQL statements, you must place them in a single quote like <code>'Infinity'<\/code> ,<code>'-Infinity'<\/code>, and <code>'NaN'<\/code>.<\/p>\n\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&nbsp;PostgreSQL&nbsp;<code>DECIMAL<\/code> data type to store numeric values that require exactness.<\/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=decimal\"\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 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