diff options
Diffstat (limited to 'doc/src')
| -rw-r--r-- | doc/src/sgml/errcodes.sgml | 19 | ||||
| -rw-r--r-- | doc/src/sgml/plpgsql.sgml | 111 |
2 files changed, 122 insertions, 8 deletions
diff --git a/doc/src/sgml/errcodes.sgml b/doc/src/sgml/errcodes.sgml index a3f56a86b14..474c0ca8da7 100644 --- a/doc/src/sgml/errcodes.sgml +++ b/doc/src/sgml/errcodes.sgml @@ -1,4 +1,4 @@ -<!-- $PostgreSQL: pgsql/doc/src/sgml/errcodes.sgml,v 1.23 2008/01/15 01:36:53 tgl Exp $ --> +<!-- $PostgreSQL: pgsql/doc/src/sgml/errcodes.sgml,v 1.24 2008/05/15 22:39:48 tgl Exp $ --> <appendix id="errcodes-appendix"> <title><productname>PostgreSQL</productname> Error Codes</title> @@ -62,14 +62,14 @@ <tgroup cols="3"> <colspec colnum="1" colname="errorcode"> - <colspec colnum="3" colname="constant"> - <spanspec namest="errorcode" nameend="constant" spanname="span13"> + <colspec colnum="3" colname="condname"> + <spanspec namest="errorcode" nameend="condname" spanname="span13"> <thead> <row> <entry>Error Code</entry> <entry>Meaning</entry> - <entry>Constant</entry> + <entry>Condition Name</entry> </row> </thead> @@ -293,6 +293,17 @@ <row> +<entry spanname="span13"><emphasis role="bold">Class 20 — Case Not Found</></entry> +</row> + +<row> +<entry><literal>20000</literal></entry> +<entry>CASE NOT FOUND</entry> +<entry>case_not_found</entry> +</row> + + +<row> <entry spanname="span13"><emphasis role="bold">Class 21 — Cardinality Violation</></entry> </row> diff --git a/doc/src/sgml/plpgsql.sgml b/doc/src/sgml/plpgsql.sgml index 09ad6944dba..d2853d2d901 100644 --- a/doc/src/sgml/plpgsql.sgml +++ b/doc/src/sgml/plpgsql.sgml @@ -1,4 +1,4 @@ -<!-- $PostgreSQL: pgsql/doc/src/sgml/plpgsql.sgml,v 1.129 2008/05/13 22:10:29 tgl Exp $ --> +<!-- $PostgreSQL: pgsql/doc/src/sgml/plpgsql.sgml,v 1.130 2008/05/15 22:39:49 tgl Exp $ --> <chapter id="plpgsql"> <title><application>PL/pgSQL</application> - <acronym>SQL</acronym> Procedural Language</title> @@ -1581,9 +1581,9 @@ SELECT * FROM getallfoo(); <title>Conditionals</title> <para> - <literal>IF</> statements let you execute commands based on - certain conditions. <application>PL/pgSQL</> has five forms of - <literal>IF</>: + <command>IF</> and <command>CASE</> statements let you execute + alternative commands based on certain conditions. + <application>PL/pgSQL</> has five forms of <command>IF</>: <itemizedlist> <listitem> <para><literal>IF ... THEN</></> @@ -1601,6 +1601,22 @@ SELECT * FROM getallfoo(); <para><literal>IF ... THEN ... ELSEIF ... THEN ... ELSE</></> </listitem> </itemizedlist> + + and four forms of <command>CASE</>: + <itemizedlist> + <listitem> + <para><literal>CASE ... WHEN ... THEN ... END CASE</></> + </listitem> + <listitem> + <para><literal>CASE ... WHEN ... THEN ... ELSE ... END CASE</></> + </listitem> + <listitem> + <para><literal>CASE WHEN ... THEN ... END CASE</></> + </listitem> + <listitem> + <para><literal>CASE WHEN ... THEN ... ELSE ... END CASE</></> + </listitem> + </itemizedlist> </para> <sect3> @@ -1751,6 +1767,93 @@ END IF; <literal>ELSEIF</> is an alias for <literal>ELSIF</>. </para> </sect3> + + <sect3> + <title>Simple <literal>CASE</></title> + +<synopsis> +CASE <replaceable>search-expression</replaceable> + WHEN <replaceable>expression</replaceable> <optional>, <replaceable>expression</replaceable> <optional> ... </optional></optional> THEN + <replaceable>statements</replaceable> + <optional> WHEN <replaceable>expression</replaceable> <optional>, <replaceable>expression</replaceable> <optional> ... </optional></optional> THEN + <replaceable>statements</replaceable> + ... </optional> + <optional> ELSE + <replaceable>statements</replaceable> </optional> +END CASE; +</synopsis> + + <para> + The simple form of <command>CASE</> provides conditional execution + based on equality of operands. The <replaceable>search-expression</> + is evaluated (once) and successively compared to each + <replaceable>expression</> in the <literal>WHEN</> clauses. + If a match is found, then the corresponding + <replaceable>statements</replaceable> are executed, and then control + passes to the next statement after <literal>END CASE</>. (Subsequent + <literal>WHEN</> expressions are not evaluated.) If no match is + found, the <literal>ELSE</> <replaceable>statements</replaceable> are + executed; but if <literal>ELSE</> is not present, then a + <literal>CASE_NOT_FOUND</literal> exception is raised. + </para> + + <para> + Here is a simple example: + +<programlisting> +CASE x + WHEN 1, 2 THEN + msg := 'one or two'; + ELSE + msg := 'other value than one or two'; +END CASE; +</programlisting> + </para> + </sect3> + + <sect3> + <title>Searched <literal>CASE</></title> + +<synopsis> +CASE + WHEN <replaceable>boolean-expression</replaceable> THEN + <replaceable>statements</replaceable> + <optional> WHEN <replaceable>boolean-expression</replaceable> THEN + <replaceable>statements</replaceable> + ... </optional> + <optional> ELSE + <replaceable>statements</replaceable> </optional> +END CASE; +</synopsis> + + <para> + The searched form of <command>CASE</> provides conditional execution + based on truth of boolean expressions. Each <literal>WHEN</> clause's + <replaceable>boolean-expression</replaceable> is evaluated in turn, + until one is found that yields <literal>true</>. Then the + corresponding <replaceable>statements</replaceable> are executed, and + then control passes to the next statement after <literal>END CASE</>. + (Subsequent <literal>WHEN</> expressions are not evaluated.) + If no true result is found, the <literal>ELSE</> + <replaceable>statements</replaceable> are executed; + but if <literal>ELSE</> is not present, then a + <literal>CASE_NOT_FOUND</literal> exception is raised. + </para> + + <para> + Here is an example: + +<programlisting> +CASE + WHEN x BETWEEN 0 AND 10 THEN + msg := 'value is between zero and ten'; + WHEN x BETWEEN 11 AND 20 THEN + msg := 'value is between eleven and twenty'; +END CASE; +</programlisting> + </para> + + </sect3> </sect2> <sect2 id="plpgsql-control-structures-loops"> |