Add support for an optional INTO clause to PL/PgSQL's EXECUTE command.
This allows the result of executing a SELECT to be assigned to a row variable, record variable, or list of scalars. Docs and regression tests updated. Per Pavel Stehule, improvements and cleanup by Neil Conway.
This commit is contained in:
Neil Conway
parent
0f011f6daa
commit
c59887f916
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@ -1,5 +1,5 @@
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<!--
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$PostgreSQL: pgsql/doc/src/sgml/plpgsql.sgml,v 1.69 2005/05/26 04:08:31 momjian Exp $
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$PostgreSQL: pgsql/doc/src/sgml/plpgsql.sgml,v 1.70 2005/06/07 02:47:15 neilc Exp $
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-->
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<chapter id="plpgsql">
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@ -1251,13 +1251,14 @@ NULL;
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<command>EXECUTE</command> statement is provided:
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<synopsis>
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EXECUTE <replaceable class="command">command-string</replaceable>;
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EXECUTE <replaceable class="command">command-string</replaceable> [ INTO <replaceable>target</replaceable> ];
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</synopsis>
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where <replaceable>command-string</replaceable> is an expression
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yielding a string (of type
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<type>text</type>) containing the command
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to be executed. This string is fed literally to the SQL engine.
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yielding a string (of type <type>text</type>) containing the
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command to be executed and <replaceable>target</replaceable> is a
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record variable, row variable, or a comma-separated list of
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simple variables and record/row fields.
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</para>
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<para>
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@ -1276,16 +1277,22 @@ EXECUTE <replaceable class="command">command-string</replaceable>;
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</para>
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<para>
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The results from <command>SELECT</command> commands are discarded
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by <command>EXECUTE</command>, and <command>SELECT INTO</command>
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is not currently supported within <command>EXECUTE</command>.
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So there is no way to extract a result from a dynamically-created
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<command>SELECT</command> using the plain <command>EXECUTE</command>
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command. There are two other ways to do it, however: one is to use the
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<command>FOR-IN-EXECUTE</>
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loop form described in <xref linkend="plpgsql-records-iterating">,
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and the other is to use a cursor with <command>OPEN-FOR-EXECUTE</>, as
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described in <xref linkend="plpgsql-cursor-opening">.
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The <literal>INTO</literal> clause specifies where the results of
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a <command>SELECT</command> command should be assigned. If a row
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or variable list is provided, it must exactly match the structure
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of the results produced by the <command>SELECT</command> (when a
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record variable is used, it will configure itself to match the
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result's structure automatically). If multiple rows are returned,
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only the first will be assigned to the <literal>INTO</literal>
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variable. If no rows are returned, NULL is assigned to the
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<literal>INTO</literal> variable. If no <literal>INTO</literal>
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clause is specified, the results of a <command>SELECT</command>
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command are discarded.
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</para>
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<para>
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<command>SELECT INTO</command> is not currently supported within
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<command>EXECUTE</command>.
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</para>
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<para>
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@ -1364,7 +1371,7 @@ EXECUTE 'UPDATE tbl SET '
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command, which has the form:
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<synopsis>
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GET DIAGNOSTICS <replaceable>variable</replaceable> = <replaceable>item</replaceable> <optional> , ... </optional> ;
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GET DIAGNOSTICS <replaceable>variable</replaceable> = <replaceable>item</replaceable> <optional> , ... </optional>;
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</synopsis>
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This command allows retrieval of system status indicators. Each
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@ -2173,7 +2180,7 @@ SELECT merge_db (1, 'dennis');
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Another way is to use the cursor declaration syntax,
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which in general is:
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<synopsis>
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<replaceable>name</replaceable> CURSOR <optional> ( <replaceable>arguments</replaceable> ) </optional> FOR <replaceable>query</replaceable> ;
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<replaceable>name</replaceable> CURSOR <optional> ( <replaceable>arguments</replaceable> ) </optional> FOR <replaceable>query</replaceable>;
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</synopsis>
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(<literal>FOR</> may be replaced by <literal>IS</> for
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<productname>Oracle</productname> compatibility.)
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@ -2218,7 +2225,7 @@ DECLARE
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<title><command>OPEN FOR</command> <replaceable>query</replaceable></title>
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<synopsis>
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OPEN <replaceable>unbound_cursor</replaceable> FOR <replaceable>query</replaceable> ;
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OPEN <replaceable>unbound_cursor</replaceable> FOR <replaceable>query</replaceable>;
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</synopsis>
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<para>
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@ -3188,7 +3195,7 @@ DECLARE
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func_body text;
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func_cmd text;
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BEGIN
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func_body := 'BEGIN' ;
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func_body := 'BEGIN';
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-- Notice how we scan through the results of a query in a FOR loop
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-- using the FOR <record> construct.
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@ -4,7 +4,7 @@
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* procedural language
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*
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* IDENTIFICATION
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* $PostgreSQL: pgsql/src/pl/plpgsql/src/gram.y,v 1.72 2005/05/26 04:08:31 momjian Exp $
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* $PostgreSQL: pgsql/src/pl/plpgsql/src/gram.y,v 1.73 2005/06/07 02:47:16 neilc Exp $
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*
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* This software is copyrighted by Jan Wieck - Hamburg.
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*
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@ -1250,19 +1250,62 @@ stmt_execsql : execsql_start lno
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}
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;
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stmt_dynexecute : K_EXECUTE lno expr_until_semi
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stmt_dynexecute : K_EXECUTE lno
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{
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PLpgSQL_stmt_dynexecute *new;
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PLpgSQL_expr *expr;
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int endtoken;
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expr = read_sql_construct(K_INTO, ';', "INTO|;", "SELECT ",
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true, true, &endtoken);
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new = palloc(sizeof(PLpgSQL_stmt_dynexecute));
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new->cmd_type = PLPGSQL_STMT_DYNEXECUTE;
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new->lineno = $2;
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new->query = $3;
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new->query = expr;
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new->rec = NULL;
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new->row = NULL;
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/*
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* If we saw "INTO", look for an additional
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* row or record var.
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*/
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if (endtoken == K_INTO)
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{
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switch (yylex())
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{
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case T_ROW:
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check_assignable((PLpgSQL_datum *) yylval.row);
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new->row = yylval.row;
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break;
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case T_RECORD:
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check_assignable((PLpgSQL_datum *) yylval.row);
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new->rec = yylval.rec;
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break;
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case T_SCALAR:
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new->row = read_into_scalar_list(yytext, yylval.scalar);
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break;
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default:
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plpgsql_error_lineno = $2;
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ereport(ERROR,
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(errcode(ERRCODE_SYNTAX_ERROR),
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errmsg("syntax error at \"%s\"",
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yytext),
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errdetail("Expected record or row variable.")));
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}
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if (yylex() != ';')
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yyerror("syntax error");
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}
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$$ = (PLpgSQL_stmt *)new;
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}
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;
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stmt_open : K_OPEN lno cursor_varptr
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{
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PLpgSQL_stmt_open *new;
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@ -3,7 +3,7 @@
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* procedural language
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*
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* IDENTIFICATION
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* $PostgreSQL: pgsql/src/pl/plpgsql/src/pl_exec.c,v 1.141 2005/05/26 04:08:31 momjian Exp $
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* $PostgreSQL: pgsql/src/pl/plpgsql/src/pl_exec.c,v 1.142 2005/06/07 02:47:17 neilc Exp $
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*
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* This software is copyrighted by Jan Wieck - Hamburg.
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*
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@ -2202,6 +2202,13 @@ exec_stmt_dynexecute(PLpgSQL_execstate *estate,
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Oid restype;
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char *querystr;
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int exec_res;
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PLpgSQL_rec *rec = NULL;
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PLpgSQL_row *row = NULL;
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if (stmt->rec != NULL)
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rec = (PLpgSQL_rec *) (estate->datums[stmt->rec->recno]);
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else if (stmt->row != NULL)
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row = (PLpgSQL_row *) (estate->datums[stmt->row->rowno]);
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/*
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* First we evaluate the string expression after the EXECUTE keyword.
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@ -2221,9 +2228,27 @@ exec_stmt_dynexecute(PLpgSQL_execstate *estate,
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/*
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* Call SPI_execute() without preparing a saved plan. The returncode can
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* be any standard OK. Note that while a SELECT is allowed, its
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* results will be discarded.
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* results will be discarded unless an INTO clause is specified.
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*/
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exec_res = SPI_execute(querystr, estate->readonly_func, 0);
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/* Assign to INTO variable */
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if (rec || row)
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{
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if (exec_res != SPI_OK_SELECT)
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ereport(ERROR,
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(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
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errmsg("EXECUTE ... INTO is only for SELECT")));
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else
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{
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if (SPI_processed == 0)
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exec_move_row(estate, rec, row, NULL, SPI_tuptable->tupdesc);
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else
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exec_move_row(estate, rec, row,
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SPI_tuptable->vals[0], SPI_tuptable->tupdesc);
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}
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}
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switch (exec_res)
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{
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case SPI_OK_SELECT:
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@ -3,7 +3,7 @@
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* procedural language
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*
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* IDENTIFICATION
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* $PostgreSQL: pgsql/src/pl/plpgsql/src/plpgsql.h,v 1.60 2005/05/26 04:08:31 momjian Exp $
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* $PostgreSQL: pgsql/src/pl/plpgsql/src/plpgsql.h,v 1.61 2005/06/07 02:47:18 neilc Exp $
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*
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* This software is copyrighted by Jan Wieck - Hamburg.
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*
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@ -524,6 +524,8 @@ typedef struct
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{ /* Dynamic SQL string to execute */
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int cmd_type;
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int lineno;
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PLpgSQL_rec *rec; /* INTO record or row variable */
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PLpgSQL_row *row;
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PLpgSQL_expr *query;
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} PLpgSQL_stmt_dynexecute;
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@ -2380,3 +2380,38 @@ ERROR: control reached end of function without RETURN
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CONTEXT: PL/pgSQL function "missing_return_expr"
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drop function void_return_expr();
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drop function missing_return_expr();
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--
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-- EXECUTE ... INTO test
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--
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create table eifoo (i integer, y integer);
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create type eitype as (i integer, y integer);
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create or replace function execute_into_test(varchar) returns record as $$
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declare
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_r record;
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_rt eifoo%rowtype;
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_v eitype;
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i int;
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j int;
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k int;
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begin
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execute 'insert into '||$1||' values(10,15)';
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execute 'select (row).* from (select row(10,1)::eifoo) s' into _r;
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raise notice '% %', _r.i, _r.y;
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execute 'select * from '||$1||' limit 1' into _rt;
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raise notice '% %', _rt.i, _rt.y;
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execute 'select *, 20 from '||$1||' limit 1' into i, j, k;
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raise notice '% % %', i, j, k;
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execute 'select 1,2' into _v;
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return _v;
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end; $$ language plpgsql;
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select execute_into_test('eifoo');
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NOTICE: 10 1
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NOTICE: 10 15
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NOTICE: 10 15 20
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execute_into_test
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-------------------
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(1,2)
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(1 row)
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drop table eifoo cascade;
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drop type eitype cascade;
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@ -2018,3 +2018,35 @@ select missing_return_expr();
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drop function void_return_expr();
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drop function missing_return_expr();
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--
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-- EXECUTE ... INTO test
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--
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create table eifoo (i integer, y integer);
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create type eitype as (i integer, y integer);
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create or replace function execute_into_test(varchar) returns record as $$
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declare
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_r record;
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_rt eifoo%rowtype;
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_v eitype;
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i int;
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j int;
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k int;
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begin
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execute 'insert into '||$1||' values(10,15)';
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execute 'select (row).* from (select row(10,1)::eifoo) s' into _r;
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raise notice '% %', _r.i, _r.y;
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execute 'select * from '||$1||' limit 1' into _rt;
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raise notice '% %', _rt.i, _rt.y;
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execute 'select *, 20 from '||$1||' limit 1' into i, j, k;
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raise notice '% % %', i, j, k;
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execute 'select 1,2' into _v;
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return _v;
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end; $$ language plpgsql;
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select execute_into_test('eifoo');
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drop table eifoo cascade;
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drop type eitype cascade;
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