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diff --git a/doc/src/sgml/html/sql-delete.html b/doc/src/sgml/html/sql-delete.html new file mode 100644 index 0000000..abb8449 --- /dev/null +++ b/doc/src/sgml/html/sql-delete.html @@ -0,0 +1,145 @@ +<?xml version="1.0" encoding="UTF-8" standalone="no"?> +<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>DELETE</title><link rel="stylesheet" type="text/css" href="stylesheet.css" /><link rev="made" href="pgsql-docs@lists.postgresql.org" /><meta name="generator" content="DocBook XSL Stylesheets Vsnapshot" /><link rel="prev" href="sql-declare.html" title="DECLARE" /><link rel="next" href="sql-discard.html" title="DISCARD" /></head><body id="docContent" class="container-fluid col-10"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="5" align="center">DELETE</th></tr><tr><td width="10%" align="left"><a accesskey="p" href="sql-declare.html" title="DECLARE">Prev</a> </td><td width="10%" align="left"><a accesskey="u" href="sql-commands.html" title="SQL Commands">Up</a></td><th width="60%" align="center">SQL Commands</th><td width="10%" align="right"><a accesskey="h" href="index.html" title="PostgreSQL 15.5 Documentation">Home</a></td><td width="10%" align="right"> <a accesskey="n" href="sql-discard.html" title="DISCARD">Next</a></td></tr></table><hr /></div><div class="refentry" id="SQL-DELETE"><div class="titlepage"></div><a id="id-1.9.3.100.1" class="indexterm"></a><div class="refnamediv"><h2><span class="refentrytitle">DELETE</span></h2><p>DELETE — delete rows of a table</p></div><div class="refsynopsisdiv"><h2>Synopsis</h2><pre class="synopsis"> +[ WITH [ RECURSIVE ] <em class="replaceable"><code>with_query</code></em> [, ...] ] +DELETE FROM [ ONLY ] <em class="replaceable"><code>table_name</code></em> [ * ] [ [ AS ] <em class="replaceable"><code>alias</code></em> ] + [ USING <em class="replaceable"><code>from_item</code></em> [, ...] ] + [ WHERE <em class="replaceable"><code>condition</code></em> | WHERE CURRENT OF <em class="replaceable"><code>cursor_name</code></em> ] + [ RETURNING * | <em class="replaceable"><code>output_expression</code></em> [ [ AS ] <em class="replaceable"><code>output_name</code></em> ] [, ...] ] +</pre></div><div class="refsect1" id="id-1.9.3.100.5"><h2>Description</h2><p> + <code class="command">DELETE</code> deletes rows that satisfy the + <code class="literal">WHERE</code> clause from the specified table. If the + <code class="literal">WHERE</code> clause is absent, the effect is to delete + all rows in the table. The result is a valid, but empty table. + </p><div class="tip"><h3 class="title">Tip</h3><p> + <a class="link" href="sql-truncate.html" title="TRUNCATE"><code class="command">TRUNCATE</code></a> provides a + faster mechanism to remove all rows from a table. + </p></div><p> + There are two ways to delete rows in a table using information + contained in other tables in the database: using sub-selects, or + specifying additional tables in the <code class="literal">USING</code> clause. + Which technique is more appropriate depends on the specific + circumstances. + </p><p> + The optional <code class="literal">RETURNING</code> clause causes <code class="command">DELETE</code> + to compute and return value(s) based on each row actually deleted. + Any expression using the table's columns, and/or columns of other + tables mentioned in <code class="literal">USING</code>, can be computed. + The syntax of the <code class="literal">RETURNING</code> list is identical to that of the + output list of <code class="command">SELECT</code>. + </p><p> + You must have the <code class="literal">DELETE</code> privilege on the table + to delete from it, as well as the <code class="literal">SELECT</code> + privilege for any table in the <code class="literal">USING</code> clause or + whose values are read in the <em class="replaceable"><code>condition</code></em>. + </p></div><div class="refsect1" id="id-1.9.3.100.6"><h2>Parameters</h2><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="replaceable"><code>with_query</code></em></span></dt><dd><p> + The <code class="literal">WITH</code> clause allows you to specify one or more + subqueries that can be referenced by name in the <code class="command">DELETE</code> + query. See <a class="xref" href="queries-with.html" title="7.8. WITH Queries (Common Table Expressions)">Section 7.8</a> and <a class="xref" href="sql-select.html" title="SELECT"><span class="refentrytitle">SELECT</span></a> + for details. + </p></dd><dt><span class="term"><em class="replaceable"><code>table_name</code></em></span></dt><dd><p> + The name (optionally schema-qualified) of the table to delete rows + from. If <code class="literal">ONLY</code> is specified before the table name, + matching rows are deleted from the named table only. If + <code class="literal">ONLY</code> is not specified, matching rows are also deleted + from any tables inheriting from the named table. Optionally, + <code class="literal">*</code> can be specified after the table name to explicitly + indicate that descendant tables are included. + </p></dd><dt><span class="term"><em class="replaceable"><code>alias</code></em></span></dt><dd><p> + A substitute name for the target table. When an alias is + provided, it completely hides the actual name of the table. For + example, given <code class="literal">DELETE FROM foo AS f</code>, the remainder + of the <code class="command">DELETE</code> statement must refer to this + table as <code class="literal">f</code> not <code class="literal">foo</code>. + </p></dd><dt><span class="term"><em class="replaceable"><code>from_item</code></em></span></dt><dd><p> + A table expression allowing columns from other tables to appear + in the <code class="literal">WHERE</code> condition. This uses the same + syntax as the <a class="link" href="sql-select.html#SQL-FROM" title="FROM Clause"><code class="literal">FROM</code></a> + clause of a <code class="command">SELECT</code> statement; for example, an alias + for the table name can be specified. Do not repeat the target + table as a <em class="replaceable"><code>from_item</code></em> + unless you wish to set up a self-join (in which case it must appear + with an alias in the <em class="replaceable"><code>from_item</code></em>). + </p></dd><dt><span class="term"><em class="replaceable"><code>condition</code></em></span></dt><dd><p> + An expression that returns a value of type <code class="type">boolean</code>. + Only rows for which this expression returns <code class="literal">true</code> + will be deleted. + </p></dd><dt><span class="term"><em class="replaceable"><code>cursor_name</code></em></span></dt><dd><p> + The name of the cursor to use in a <code class="literal">WHERE CURRENT OF</code> + condition. The row to be deleted is the one most recently fetched + from this cursor. The cursor must be a non-grouping + query on the <code class="command">DELETE</code>'s target table. + Note that <code class="literal">WHERE CURRENT OF</code> cannot be + specified together with a Boolean condition. See + <a class="xref" href="sql-declare.html" title="DECLARE"><span class="refentrytitle">DECLARE</span></a> + for more information about using cursors with + <code class="literal">WHERE CURRENT OF</code>. + </p></dd><dt><span class="term"><em class="replaceable"><code>output_expression</code></em></span></dt><dd><p> + An expression to be computed and returned by the <code class="command">DELETE</code> + command after each row is deleted. The expression can use any + column names of the table named by <em class="replaceable"><code>table_name</code></em> + or table(s) listed in <code class="literal">USING</code>. + Write <code class="literal">*</code> to return all columns. + </p></dd><dt><span class="term"><em class="replaceable"><code>output_name</code></em></span></dt><dd><p> + A name to use for a returned column. + </p></dd></dl></div></div><div class="refsect1" id="id-1.9.3.100.7"><h2>Outputs</h2><p> + On successful completion, a <code class="command">DELETE</code> command returns a command + tag of the form +</p><pre class="screen"> +DELETE <em class="replaceable"><code>count</code></em> +</pre><p> + The <em class="replaceable"><code>count</code></em> is the number + of rows deleted. Note that the number may be less than the number of + rows that matched the <em class="replaceable"><code>condition</code></em> when deletes were + suppressed by a <code class="literal">BEFORE DELETE</code> trigger. If <em class="replaceable"><code>count</code></em> is 0, no rows were deleted by + the query (this is not considered an error). + </p><p> + If the <code class="command">DELETE</code> command contains a <code class="literal">RETURNING</code> + clause, the result will be similar to that of a <code class="command">SELECT</code> + statement containing the columns and values defined in the + <code class="literal">RETURNING</code> list, computed over the row(s) deleted by the + command. + </p></div><div class="refsect1" id="id-1.9.3.100.8"><h2>Notes</h2><p> + <span class="productname">PostgreSQL</span> lets you reference columns of + other tables in the <code class="literal">WHERE</code> condition by specifying the + other tables in the <code class="literal">USING</code> clause. For example, + to delete all films produced by a given producer, one can do: +</p><pre class="programlisting"> +DELETE FROM films USING producers + WHERE producer_id = producers.id AND producers.name = 'foo'; +</pre><p> + What is essentially happening here is a join between <code class="structname">films</code> + and <code class="structname">producers</code>, with all successfully joined + <code class="structname">films</code> rows being marked for deletion. + This syntax is not standard. A more standard way to do it is: +</p><pre class="programlisting"> +DELETE FROM films + WHERE producer_id IN (SELECT id FROM producers WHERE name = 'foo'); +</pre><p> + In some cases the join style is easier to write or faster to + execute than the sub-select style. + </p></div><div class="refsect1" id="id-1.9.3.100.9"><h2>Examples</h2><p> + Delete all films but musicals: +</p><pre class="programlisting"> +DELETE FROM films WHERE kind <> 'Musical'; +</pre><p> + </p><p> + Clear the table <code class="literal">films</code>: +</p><pre class="programlisting"> +DELETE FROM films; +</pre><p> + </p><p> + Delete completed tasks, returning full details of the deleted rows: +</p><pre class="programlisting"> +DELETE FROM tasks WHERE status = 'DONE' RETURNING *; +</pre><p> + </p><p> + Delete the row of <code class="structname">tasks</code> on which the cursor + <code class="literal">c_tasks</code> is currently positioned: +</p><pre class="programlisting"> +DELETE FROM tasks WHERE CURRENT OF c_tasks; +</pre></div><div class="refsect1" id="id-1.9.3.100.10"><h2>Compatibility</h2><p> + This command conforms to the <acronym class="acronym">SQL</acronym> standard, except + that the <code class="literal">USING</code> and <code class="literal">RETURNING</code> clauses + are <span class="productname">PostgreSQL</span> extensions, as is the ability + to use <code class="literal">WITH</code> with <code class="command">DELETE</code>. + </p></div><div class="refsect1" id="id-1.9.3.100.11"><h2>See Also</h2><span class="simplelist"><a class="xref" href="sql-truncate.html" title="TRUNCATE"><span class="refentrytitle">TRUNCATE</span></a></span></div></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="sql-declare.html" title="DECLARE">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="sql-commands.html" title="SQL Commands">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="sql-discard.html" title="DISCARD">Next</a></td></tr><tr><td width="40%" align="left" valign="top">DECLARE </td><td width="20%" align="center"><a accesskey="h" href="index.html" title="PostgreSQL 15.5 Documentation">Home</a></td><td width="40%" align="right" valign="top"> DISCARD</td></tr></table></div></body></html>
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