blob: e95278af288c7cd47817af5338835b1f8c424cbd (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
|
<!--
$PostgreSQL: pgsql/doc/src/sgml/ref/update.sgml,v 1.27 2003/11/29 19:51:39 pgsql Exp $
PostgreSQL documentation
-->
<refentry id="SQL-UPDATE">
<refmeta>
<refentrytitle id="SQL-UPDATE-TITLE">UPDATE</refentrytitle>
<refmiscinfo>SQL - Language Statements</refmiscinfo>
</refmeta>
<refnamediv>
<refname>UPDATE</refname>
<refpurpose>update rows of a table</refpurpose>
</refnamediv>
<indexterm zone="sql-update">
<primary>UPDATE</primary>
</indexterm>
<refsynopsisdiv>
<synopsis>
UPDATE [ ONLY ] <replaceable class="PARAMETER">table</replaceable> SET <replaceable class="PARAMETER">column</replaceable> = { <replaceable class="PARAMETER">expression</replaceable> | DEFAULT } [, ...]
[ FROM <replaceable class="PARAMETER">fromlist</replaceable> ]
[ WHERE <replaceable class="PARAMETER">condition</replaceable> ]
</synopsis>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para>
<command>UPDATE</command> 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 statement; columns not explicitly
<literal>SET</> retain their previous values.
</para>
<para>
By default, <command>UPDATE</command> will update rows in the
specified table and all its subtables. If you wish to only update
the specific table mentioned, you must use the <literal>ONLY</>
clause.
</para>
<para>
You must have the <literal>UPDATE</literal> privilege on the table
to update it, as well as the <literal>SELECT</literal>
privilege to any table whose values are read in the
<replaceable class="parameter">expression</replaceable>s or
<replaceable class="parameter">condition</replaceable>.
</para>
</refsect1>
<refsect1>
<title>Parameters</title>
<variablelist>
<varlistentry>
<term><replaceable class="PARAMETER">table</replaceable></term>
<listitem>
<para>
The name (optionally schema-qualified) of the table to update.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="PARAMETER">column</replaceable></term>
<listitem>
<para>
The name of a column in <replaceable class="PARAMETER">table</replaceable>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="PARAMETER">expression</replaceable></term>
<listitem>
<para>
An expression to assign to the column. The expression may use the
old values of this and other columns in the table.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>DEFAULT</literal></term>
<listitem>
<para>
Set the column to its default value (which will be NULL if no
specific default expression has been assigned to it).
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="PARAMETER">fromlist</replaceable></term>
<listitem>
<para>
A list of table expressions, allowing columns from other tables
to appear in the <literal>WHERE</> condition and the update expressions.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="PARAMETER">condition</replaceable></term>
<listitem>
<para>
An expression that returns a value of type <type>boolean</type>.
Only rows for which this expression returns <literal>true</>
will be updated.
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>Outputs</title>
<para>
On successful completion, an <command>UPDATE</> command returns a command
tag of the form
<screen>
UPDATE <replaceable class="parameter">count</replaceable>
</screen>
The <replaceable class="parameter">count</replaceable> is the number
of rows updated. If <replaceable class="parameter">count</replaceable> is
0, no rows matched the <replaceable
class="parameter">condition</replaceable> (this is not considered
an error).
</para>
</refsect1>
<refsect1>
<title>Examples</title>
<para>
Change the word <literal>Drama</> to <literal>Dramatic</> in the
column <structfield>kind</> of the table <literal>films</literal>:
<programlisting>
UPDATE films SET kind = 'Dramatic' WHERE kind = 'Drama';
</programlisting>
</para>
<para>
Adjust temperature entries and reset precipitation to its default
value in one row of the table <literal>weather</literal>:
<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';
</programlisting>
</para>
</refsect1>
<refsect1>
<title>Compatibility</title>
<para>
This command conforms to the SQL standard. The
<literal>FROM</literal> clause is a
<productname>PostgreSQL</productname> extension.
</para>
</refsect1>
</refentry>
<!-- Keep this comment at the end of the file
Local variables:
mode: sgml
sgml-omittag:nil
sgml-shorttag:t
sgml-minimize-attributes:nil
sgml-always-quote-attributes:t
sgml-indent-step:1
sgml-indent-data:t
sgml-parent-document:nil
sgml-default-dtd-file:"../reference.ced"
sgml-exposed-tags:nil
sgml-local-catalogs:"/usr/lib/sgml/catalog"
sgml-local-ecat-files:nil
End:
-->
|