diff options
Diffstat (limited to 'doc/src')
| -rw-r--r-- | doc/src/sgml/plpgsql.sgml | 32 |
1 files changed, 26 insertions, 6 deletions
diff --git a/doc/src/sgml/plpgsql.sgml b/doc/src/sgml/plpgsql.sgml index a04ab139123..1866e43e0e6 100644 --- a/doc/src/sgml/plpgsql.sgml +++ b/doc/src/sgml/plpgsql.sgml @@ -328,15 +328,17 @@ arow RECORD; <para> The general syntax of a variable declaration is: <synopsis> -<replaceable>name</replaceable> <optional> CONSTANT </optional> <replaceable>type</replaceable> <optional> NOT NULL </optional> <optional> { DEFAULT | := } <replaceable>expression</replaceable> </optional>; +<replaceable>name</replaceable> <optional> CONSTANT </optional> <replaceable>type</replaceable> <optional> COLLATE <replaceable>collation_name</replaceable> </optional> <optional> NOT NULL </optional> <optional> { DEFAULT | := } <replaceable>expression</replaceable> </optional>; </synopsis> The <literal>DEFAULT</> clause, if given, specifies the initial value assigned to the variable when the block is entered. If the <literal>DEFAULT</> clause is not given then the variable is initialized to the <acronym>SQL</acronym> null value. The <literal>CONSTANT</> option prevents the variable from being - assigned to, so that its value will remain constant for the duration of - the block. + assigned to after initialization, so that its value will remain constant + for the duration of the block. + The <literal>COLLATE</> option specifies a collation to use for the + variable (see <xref linkend="plpgsql-declaration-collation">). If <literal>NOT NULL</> is specified, an assignment of a null value results in a run-time error. All variables declared as <literal>NOT NULL</> @@ -768,9 +770,23 @@ $$ LANGUAGE plpgsql; </para> <para> - Explicit <literal>COLLATE</> clauses can be written inside a function - if it is desired to force a particular collation to be used regardless - of what the function is called with. For example, + A local variable of a collatable data type can have a different collation + associated with it by including the <literal>COLLATE</> option in its + declaration, for example + +<programlisting> +DECLARE + local_a text COLLATE "en_US"; +</programlisting> + + This option overrides the collation that would otherwise be + given to the variable according to the rules above. + </para> + + <para> + Also, of course explicit <literal>COLLATE</> clauses can be written inside + a function if it is desired to force a particular collation to be used in + a particular operation. For example, <programlisting> CREATE FUNCTION less_than_c(a text, b text) RETURNS boolean AS $$ @@ -779,6 +795,10 @@ BEGIN END; $$ LANGUAGE plpgsql; </programlisting> + + This overrides the collations associated with the table columns, + parameters, or local variables used in the expression, just as would + happen in a plain SQL command. </para> </sect2> </sect1> |