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<!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>UPDATE</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-unlisten.html" title="UNLISTEN" /><link rel="next" href="sql-vacuum.html" title="VACUUM" /></head><body><div xmlns="http://www.w3.org/TR/xhtml1/transitional" class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="5" align="center">UPDATE</th></tr><tr><td width="10%" align="left"><a accesskey="p" href="sql-unlisten.html" title="UNLISTEN">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 11.5 Documentation">Home</a></td><td width="10%" align="right"> <a accesskey="n" href="sql-vacuum.html" title="VACUUM">Next</a></td></tr></table><hr></hr></div><div class="refentry" id="SQL-UPDATE"><div class="titlepage"></div><a id="id-1.9.3.182.1" class="indexterm"></a><div class="refnamediv"><h2><span class="refentrytitle">UPDATE</span></h2><p>UPDATE — update 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> [, ...] ]
UPDATE [ ONLY ] <em class="replaceable"><code>table_name</code></em> [ * ] [ [ AS ] <em class="replaceable"><code>alias</code></em> ]
SET { <em class="replaceable"><code>column_name</code></em> = { <em class="replaceable"><code>expression</code></em> | DEFAULT } |
( <em class="replaceable"><code>column_name</code></em> [, ...] ) = [ ROW ] ( { <em class="replaceable"><code>expression</code></em> | DEFAULT } [, ...] ) |
( <em class="replaceable"><code>column_name</code></em> [, ...] ) = ( <em class="replaceable"><code>sub-SELECT</code></em> )
} [, ...]
[ FROM <em class="replaceable"><code>from_list</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-1.9.3.182.5"><h2>Description</h2><p>
<code class="command">UPDATE</code> changes the values of the specified
columns in all rows that satisfy the condition. Only the columns to
be modified need be mentioned in the <code class="literal">SET</code> clause;
columns not explicitly modified retain their previous values.
</p><p>
There are two ways to modify a table using information contained in
other tables in the database: using sub-selects, or specifying
additional tables in the <code class="literal">FROM</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">UPDATE</code>
to compute and return value(s) based on each row actually updated.
Any expression using the table's columns, and/or columns of other
tables mentioned in <code class="literal">FROM</code>, can be computed.
The new (post-update) values of the table's columns are used.
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">UPDATE</code> privilege on the table,
or at least on the column(s) that are listed to be updated.
You must also have the <code class="literal">SELECT</code>
privilege on any column whose values are read in the
<em class="replaceable"><code>expressions</code></em> or
<em class="replaceable"><code>condition</code></em>.
</p></div><div class="refsect1" id="id-1.9.3.182.6"><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">UPDATE</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 update.
If <code class="literal">ONLY</code> is specified before the table name, matching rows
are updated in the named table only. If <code class="literal">ONLY</code> is not
specified, matching rows are also updated in 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">UPDATE foo AS f</code>, the remainder of the
<code class="command">UPDATE</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>column_name</code></em></span></dt><dd><p>
The name of a column in the table named by <em class="replaceable"><code>table_name</code></em>.
The column name can be qualified with a subfield name or array
subscript, if needed. Do not include the table's name in the
specification of a target column — for example,
<code class="literal">UPDATE table_name SET table_name.col = 1</code> is invalid.
</p></dd><dt><span class="term"><em class="replaceable"><code>expression</code></em></span></dt><dd><p>
An expression to assign to the column. The expression can use the
old values of this and other columns in the table.
</p></dd><dt><span class="term"><code class="literal">DEFAULT</code></span></dt><dd><p>
Set the column to its default value (which will be NULL if no
specific default expression has been assigned to it).
</p></dd><dt><span class="term"><em class="replaceable"><code>sub-SELECT</code></em></span></dt><dd><p>
A <code class="literal">SELECT</code> sub-query that produces as many output columns
as are listed in the parenthesized column list preceding it. The
sub-query must yield no more than one row when executed. If it
yields one row, its column values are assigned to the target columns;
if it yields no rows, NULL values are assigned to the target columns.
The sub-query can refer to old values of the current row of the table
being updated.
</p></dd><dt><span class="term"><em class="replaceable"><code>from_list</code></em></span></dt><dd><p>
A list of table expressions, allowing columns from other tables
to appear in the <code class="literal">WHERE</code> condition and the update
expressions. This is similar to the list of tables that can be
specified in the <a class="xref" href="sql-select.html#SQL-FROM" title="FROM Clause"><code class="literal">FROM</code> Clause</a> of a <code class="command">SELECT</code>
statement. Note that the target table must not appear in the
<em class="replaceable"><code>from_list</code></em>, unless you intend a self-join (in which
case it must appear with an alias in the <em class="replaceable"><code>from_list</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 updated.
</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 updated is the one most recently fetched
from this cursor. The cursor must be a non-grouping
query on the <code class="command">UPDATE</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">UPDATE</code>
command after each row is updated. 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">FROM</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-1.9.3.182.7"><h2>Outputs</h2><p>
On successful completion, an <code class="command">UPDATE</code> command returns a command
tag of the form
</p><pre class="screen">
UPDATE <em class="replaceable"><code>count</code></em>
</pre><p>
The <em class="replaceable"><code>count</code></em> is the number
of rows updated, including matched rows whose values did not change.
Note that the number may be less than the number of rows that matched
the <em class="replaceable"><code>condition</code></em> when
updates were suppressed by a <code class="literal">BEFORE UPDATE</code> trigger. If
<em class="replaceable"><code>count</code></em> is 0, no rows were
updated by the query (this is not considered an error).
</p><p>
If the <code class="command">UPDATE</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) updated by the
command.
</p></div><div class="refsect1" id="id-1.9.3.182.8"><h2>Notes</h2><p>
When a <code class="literal">FROM</code> clause is present, what essentially happens
is that the target table is joined to the tables mentioned in the
<em class="replaceable"><code>from_list</code></em>, and each output row of the join
represents an update operation for the target table. When using
<code class="literal">FROM</code> you should ensure that the join
produces at most one output row for each row to be modified. In
other words, a target row shouldn't join to more than one row from
the other table(s). If it does, then only one of the join rows
will be used to update the target row, but which one will be used
is not readily predictable.
</p><p>
Because of this indeterminacy, referencing other tables only within
sub-selects is safer, though often harder to read and slower than
using a join.
</p><p>
In the case of a partitioned table, updating a row might cause it to no
longer satisfy the partition constraint of the containing partition. In that
case, if there is some other partition in the partition tree for which this
row satisfies its partition constraint, then the row is moved to that
partition. If there is no such partition, an error will occur. Behind the
scenes, the row movement is actually a <code class="command">DELETE</code> and
<code class="command">INSERT</code> operation.
</p><p>
There is a possibility that a concurrent <code class="command">UPDATE</code> or
<code class="command">DELETE</code> on the row being moved will get a serialization
failure error. Suppose session 1 is performing an <code class="command">UPDATE</code>
on a partition key, and meanwhile a concurrent session 2 for which this
row is visible performs an <code class="command">UPDATE</code> or
<code class="command">DELETE</code> operation on this row. In such case,
session 2's <code class="command">UPDATE</code> or <code class="command">DELETE</code> will
detect the row movement and raise a serialization failure error (which
always returns with an SQLSTATE code '40001'). Applications may wish to
retry the transaction if this occurs. In the usual case where the table
is not partitioned, or where there is no row movement, session 2 would
have identified the newly updated row and carried out the
<code class="command">UPDATE</code>/<code class="command">DELETE</code> on this new row
version.
</p><p>
Note that while rows can be moved from local partitions to a foreign-table
partition (provided the foreign data wrapper supports tuple routing), they
cannot be moved from a foreign-table partition to another partition.
</p></div><div class="refsect1" id="id-1.9.3.182.9"><h2>Examples</h2><p>
Change the word <code class="literal">Drama</code> to <code class="literal">Dramatic</code> in the
column <code class="structfield">kind</code> of the table <code class="structname">films</code>:
</p><pre class="programlisting">
UPDATE films SET kind = 'Dramatic' WHERE kind = 'Drama';
</pre><p>
</p><p>
Adjust temperature entries and reset precipitation to its default
value in one row of the table <code class="structname">weather</code>:
</p><pre class="programlisting">
UPDATE weather SET temp_lo = temp_lo+1, temp_hi = temp_lo+15, prcp = DEFAULT
WHERE city = 'San Francisco' AND date = '2003-07-03';
</pre><p>
</p><p>
Perform the same operation and return the updated entries:
</p><pre class="programlisting">
UPDATE weather SET temp_lo = temp_lo+1, temp_hi = temp_lo+15, prcp = DEFAULT
WHERE city = 'San Francisco' AND date = '2003-07-03'
RETURNING temp_lo, temp_hi, prcp;
</pre><p>
</p><p>
Use the alternative column-list syntax to do the same update:
</p><pre class="programlisting">
UPDATE weather SET (temp_lo, temp_hi, prcp) = (temp_lo+1, temp_lo+15, DEFAULT)
WHERE city = 'San Francisco' AND date = '2003-07-03';
</pre><p>
</p><p>
Increment the sales count of the salesperson who manages the
account for Acme Corporation, using the <code class="literal">FROM</code>
clause syntax:
</p><pre class="programlisting">
UPDATE employees SET sales_count = sales_count + 1 FROM accounts
WHERE accounts.name = 'Acme Corporation'
AND employees.id = accounts.sales_person;
</pre><p>
</p><p>
Perform the same operation, using a sub-select in the
<code class="literal">WHERE</code> clause:
</p><pre class="programlisting">
UPDATE employees SET sales_count = sales_count + 1 WHERE id =
(SELECT sales_person FROM accounts WHERE name = 'Acme Corporation');
</pre><p>
</p><p>
Update contact names in an accounts table to match the currently assigned
salesmen:
</p><pre class="programlisting">
UPDATE accounts SET (contact_first_name, contact_last_name) =
(SELECT first_name, last_name FROM salesmen
WHERE salesmen.id = accounts.sales_id);
</pre><p>
A similar result could be accomplished with a join:
</p><pre class="programlisting">
UPDATE accounts SET contact_first_name = first_name,
contact_last_name = last_name
FROM salesmen WHERE salesmen.id = accounts.sales_id;
</pre><p>
However, the second query may give unexpected results
if <code class="structname">salesmen</code>.<code class="structfield">id</code> is not a unique key, whereas
the first query is guaranteed to raise an error if there are multiple
<code class="structfield">id</code> matches. Also, if there is no match for a particular
<code class="structname">accounts</code>.<code class="structfield">sales_id</code> entry, the first query
will set the corresponding name fields to NULL, whereas the second query
will not update that row at all.
</p><p>
Update statistics in a summary table to match the current data:
</p><pre class="programlisting">
UPDATE summary s SET (sum_x, sum_y, avg_x, avg_y) =
(SELECT sum(x), sum(y), avg(x), avg(y) FROM data d
WHERE d.group_id = s.group_id);
</pre><p>
</p><p>
Attempt to insert a new stock item along with the quantity of stock. If
the item already exists, instead update the stock count of the existing
item. To do this without failing the entire transaction, use savepoints:
</p><pre class="programlisting">
BEGIN;
-- other operations
SAVEPOINT sp1;
INSERT INTO wines VALUES('Chateau Lafite 2003', '24');
-- Assume the above fails because of a unique key violation,
-- so now we issue these commands:
ROLLBACK TO sp1;
UPDATE wines SET stock = stock + 24 WHERE winename = 'Chateau Lafite 2003';
-- continue with other operations, and eventually
COMMIT;
</pre><p>
</p><p>
Change the <code class="structfield">kind</code> column of the table
<code class="structname">films</code> in the row on which the cursor
<code class="literal">c_films</code> is currently positioned:
</p><pre class="programlisting">
UPDATE films SET kind = 'Dramatic' WHERE CURRENT OF c_films;
</pre></div><div class="refsect1" id="id-1.9.3.182.10"><h2>Compatibility</h2><p>
This command conforms to the <acronym class="acronym">SQL</acronym> standard, except
that the <code class="literal">FROM</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">UPDATE</code>.
</p><p>
Some other database systems offer a <code class="literal">FROM</code> option in which
the target table is supposed to be listed again within <code class="literal">FROM</code>.
That is not how <span class="productname">PostgreSQL</span> interprets
<code class="literal">FROM</code>. Be careful when porting applications that use this
extension.
</p><p>
According to the standard, the source value for a parenthesized sub-list of
target column names can be any row-valued expression yielding the correct
number of columns. <span class="productname">PostgreSQL</span> only allows the
source value to be a <a class="link" href="sql-expressions.html#SQL-SYNTAX-ROW-CONSTRUCTORS" title="4.2.13. Row Constructors">row
constructor</a> or a sub-<code class="literal">SELECT</code>. An individual column's
updated value can be specified as <code class="literal">DEFAULT</code> in the
row-constructor case, but not inside a sub-<code class="literal">SELECT</code>.
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