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doc: adjust UPDATE/DELETE's FROM/USING to match SELECT's FROM 

Previously the syntax and wording were unclear.

Reported-by: Alexey Bashtanov

Discussion: https://postgr.es/m/968d4724-8e58-788f-7c45-f7b1813824cc@imap.cc

Backpatch-through: 9.5
This commit is contained in:
Bruce Momjian 2020-03-31 16:31:44 -04:00
parent 5b22ff764b
commit 3ee692d82f
2 changed files with 21 additions and 21 deletions
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20
doc/src/sgml/ref/delete.sgml
View File

@ -23,7 +23,7 @@ PostgreSQL documentation
<synopsis>
[ WITH [ RECURSIVE ] <replaceable class="parameter">with_query</replaceable> [, ...] ]
DELETE FROM [ ONLY ] <replaceable class="parameter">table_name</replaceable> [ * ] [ [ AS ] <replaceable class="parameter">alias</replaceable> ]
[ USING <replaceable class="parameter">using_list</replaceable> ]
[ USING <replaceable class="parameter">from_item</replaceable> [, ...] ]
[ WHERE <replaceable class="parameter">condition</replaceable> | WHERE CURRENT OF <replaceable class="parameter">cursor_name</replaceable> ]
[ RETURNING * | <replaceable class="parameter">output_expression</replaceable> [ [ AS ] <replaceable class="parameter">output_name</replaceable> ] [, ...] ]
</synopsis>
@ -117,17 +117,17 @@ DELETE FROM [ ONLY ] <replaceable class="parameter">table_name</replaceable> [ *
</varlistentry>
<varlistentry>
<term><replaceable class="parameter">using_list</replaceable></term>
<term><replaceable class="parameter">from_item</replaceable></term>
<listitem>
<para>
A list of table expressions, allowing columns from other tables
to appear in the <literal>WHERE</literal> condition. This is similar
to the list of tables that can be specified in the <xref
linkend="sql-from" endterm="sql-from-title"/> of a
<command>SELECT</command> statement; for example, an alias for
the table name can be specified. Do not repeat the target table
in the <replaceable class="parameter">using_list</replaceable>,
unless you wish to set up a self-join.
A table expression allowing columns from other tables to appear
in the <literal>WHERE</literal> condition. This uses the same
syntax as the <xref linkend="sql-from" endterm="sql-from-title"/>
of a <command>SELECT</command> statement; for example, an alias
for the table name can be specified. Do not repeat the target
table as a <replaceable class="parameter">from_item</replaceable>
unless you wish to set up a self-join (in which case it must appear
with an alias in the <replaceable>from_item</replaceable>).
</para>
</listitem>
</varlistentry>

22
doc/src/sgml/ref/update.sgml
View File

@ -27,7 +27,7 @@ UPDATE [ ONLY ] <replaceable class="parameter">table_name</replaceable> [ * ] [
( <replaceable class="parameter">column_name</replaceable> [, ...] ) = [ ROW ] ( { <replaceable class="parameter">expression</replaceable> | DEFAULT } [, ...] ) |
( <replaceable class="parameter">column_name</replaceable> [, ...] ) = ( <replaceable class="parameter">sub-SELECT</replaceable> )
} [, ...]
[ FROM <replaceable class="parameter">from_list</replaceable> ]
[ FROM <replaceable class="parameter">from_item</replaceable> [, ...] ]
[ WHERE <replaceable class="parameter">condition</replaceable> | WHERE CURRENT OF <replaceable class="parameter">cursor_name</replaceable> ]
[ RETURNING * | <replaceable class="parameter">output_expression</replaceable> [ [ AS ] <replaceable class="parameter">output_name</replaceable> ] [, ...] ]
</synopsis>
@ -164,17 +164,17 @@ UPDATE [ ONLY ] <replaceable class="parameter">table_name</replaceable> [ * ] [
</varlistentry>
<varlistentry>
<term><replaceable class="parameter">from_list</replaceable></term>
<term><replaceable class="parameter">from_item</replaceable></term>
<listitem>
<para>
A list of table expressions, allowing columns from other tables
to appear in the <literal>WHERE</literal> condition and the update
expressions. This is similar to the list of tables that can be
specified in the <xref linkend="sql-from"
endterm="sql-from-title"/> of a <command>SELECT</command>
statement. Note that the target table must not appear in the
<replaceable>from_list</replaceable>, unless you intend a self-join (in which
case it must appear with an alias in the <replaceable>from_list</replaceable>).
A table expression allowing columns from other tables to appear in
the <literal>WHERE</literal> condition and update expressions. This
uses the same syntax as the <xref linkend="sql-from"
endterm="sql-from-title"/> of a <command>SELECT</command> statement;
for example, an alias for the table name can be specified. Do not
repeat the target table as a <replaceable>from_item</replaceable>
unless you intend a self-join (in which case it must appear with
an alias in the <replaceable>from_item</replaceable>).
</para>
</listitem>
</varlistentry>
@ -264,7 +264,7 @@ UPDATE <replaceable class="parameter">count</replaceable>
<para>
When a <literal>FROM</literal> clause is present, what essentially happens
is that the target table is joined to the tables mentioned in the
<replaceable>from_list</replaceable>, and each output row of the join
<replaceable>from_item</replaceable> list, and each output row of the join
represents an update operation for the target table. When using
<literal>FROM</literal> you should ensure that the join
produces at most one output row for each row to be modified. In