Code review for UPDATE SET (columnlist) patch. Make it handle as much
of the syntax as this fundamentally dead-end approach can, in particular combinations of single and multi column assignments. Improve rather inadequate documentation and provide some regression tests.
This commit is contained in:
Tom Lane
parent
676d1b4e67
commit
091fe03775
@ -1,5 +1,5 @@
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<!--
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$PostgreSQL: pgsql/doc/src/sgml/ref/update.sgml,v 1.39 2006/09/02 20:34:47 momjian Exp $
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$PostgreSQL: pgsql/doc/src/sgml/ref/update.sgml,v 1.40 2006/09/03 22:37:05 tgl Exp $
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PostgreSQL documentation
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-->
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@ -21,8 +21,8 @@ PostgreSQL documentation
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<refsynopsisdiv>
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<synopsis>
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UPDATE [ ONLY ] <replaceable class="PARAMETER">table</replaceable> [ [ AS ] <replaceable class="parameter">alias</replaceable> ]
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[ SET <replaceable class="PARAMETER">column</replaceable> = { <replaceable class="PARAMETER">expression</replaceable> | DEFAULT } [, ...] |
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SET ( <replaceable class="PARAMETER">column</replaceable> [, ...] ) = ( { <replaceable class="PARAMETER">expression</replaceable> | DEFAULT } [, ...] ) [, ...] ]
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SET { <replaceable class="PARAMETER">column</replaceable> = { <replaceable class="PARAMETER">expression</replaceable> | DEFAULT } |
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( <replaceable class="PARAMETER">column</replaceable> [, ...] ) = ( { <replaceable class="PARAMETER">expression</replaceable> | DEFAULT } [, ...] ) } [, ...]
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[ FROM <replaceable class="PARAMETER">fromlist</replaceable> ]
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[ WHERE <replaceable class="PARAMETER">condition</replaceable> ]
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[ RETURNING * | <replaceable class="parameter">output_expression</replaceable> [ AS <replaceable class="parameter">output_name</replaceable> ] [, ...] ]
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@ -251,10 +251,6 @@ UPDATE films SET kind = 'Dramatic' WHERE kind = 'Drama';
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<programlisting>
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UPDATE weather SET temp_lo = temp_lo+1, temp_hi = temp_lo+15, prcp = DEFAULT
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WHERE city = 'San Francisco' AND date = '2003-07-03';
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</programlisting>
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<programlisting>
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UPDATE weather SET (temp_lo, temp_hi, prcp) = (temp_lo+1, temp_lo+15, DEFAULT)
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WHERE city = 'San Francisco' AND date = '2003-07-03';
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</programlisting>
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</para>
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@ -268,6 +264,14 @@ UPDATE weather SET temp_lo = temp_lo+1, temp_hi = temp_lo+15, prcp = DEFAULT
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</programlisting>
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</para>
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<para>
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Use the alternative column-list syntax to do the same update:
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<programlisting>
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UPDATE weather SET (temp_lo, temp_hi, prcp) = (temp_lo+1, temp_lo+15, DEFAULT)
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WHERE city = 'San Francisco' AND date = '2003-07-03';
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</programlisting>
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</para>
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<para>
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Increment the sales count of the salesperson who manages the
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account for Acme Corporation, using the <literal>FROM</literal>
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@ -316,6 +320,19 @@ COMMIT;
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are <productname>PostgreSQL</productname> extensions.
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</para>
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<para>
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According to the standard, the column-list syntax should allow a list
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of columns to be assigned from a single row-valued expression, such
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as a sub-select:
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<programlisting>
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UPDATE accounts SET (contact_last_name, contact_first_name) =
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(SELECT last_name, first_name FROM salesmen
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WHERE salesmen.id = accounts.sales_id);
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</programlisting>
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This is not currently implemented — the source must be a list
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of independent expressions.
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</para>
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<para>
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Some other database systems offer a <literal>FROM</> option in which
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the target table is supposed to be listed again within <literal>FROM</>.
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@ -11,7 +11,7 @@
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*
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*
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* IDENTIFICATION
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* $PostgreSQL: pgsql/src/backend/parser/gram.y,v 2.564 2006/09/03 03:19:44 momjian Exp $
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* $PostgreSQL: pgsql/src/backend/parser/gram.y,v 2.565 2006/09/03 22:37:05 tgl Exp $
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*
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* HISTORY
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* AUTHOR DATE MAJOR EVENT
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@ -236,9 +236,9 @@ static void doNegateFloat(Value *v);
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name_list from_clause from_list opt_array_bounds
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qualified_name_list any_name any_name_list
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any_operator expr_list attrs
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target_list update_col_list update_target_list
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update_value_list set_opt insert_column_list
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values_list def_list indirection opt_indirection
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target_list insert_column_list set_target_list
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set_clause_list set_clause multiple_set_clause
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ctext_expr_list ctext_row def_list indirection opt_indirection
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group_clause TriggerFuncArgs select_limit
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opt_select_limit opclass_item_list
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transaction_mode_list_or_empty
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@ -299,7 +299,7 @@ static void doNegateFloat(Value *v);
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%type <list> when_clause_list
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%type <ival> sub_type
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%type <list> OptCreateAs CreateAsList
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%type <node> CreateAsElement values_item
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%type <node> CreateAsElement ctext_expr
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%type <value> NumericOnly FloatOnly IntegerOnly
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%type <alias> alias_clause
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%type <sortby> sortby
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@ -308,8 +308,7 @@ static void doNegateFloat(Value *v);
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%type <jexpr> joined_table
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%type <range> relation_expr
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%type <range> relation_expr_opt_alias
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%type <target> target_el update_target_el update_col_list_el insert_column_item
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%type <list> update_target_lists_list update_target_lists_el
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%type <target> target_el single_set_clause set_target insert_column_item
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%type <typnam> Typename SimpleTypename ConstTypename
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GenericType Numeric opt_float
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@ -5488,7 +5487,7 @@ opt_nowait: NOWAIT { $$ = TRUE; }
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*****************************************************************************/
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UpdateStmt: UPDATE relation_expr_opt_alias
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SET set_opt
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SET set_clause_list
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from_clause
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where_clause
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returning_clause
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@ -5503,9 +5502,65 @@ UpdateStmt: UPDATE relation_expr_opt_alias
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}
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;
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set_opt:
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update_target_list { $$ = $1; }
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| update_target_lists_list { $$ = $1; }
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set_clause_list:
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set_clause { $$ = $1; }
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| set_clause_list ',' set_clause { $$ = list_concat($1,$3); }
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;
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set_clause:
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single_set_clause { $$ = list_make1($1); }
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| multiple_set_clause { $$ = $1; }
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;
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single_set_clause:
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set_target '=' ctext_expr
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{
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$$ = $1;
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$$->val = (Node *) $3;
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}
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;
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multiple_set_clause:
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'(' set_target_list ')' '=' ctext_row
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{
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ListCell *col_cell;
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ListCell *val_cell;
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/*
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* Break the ctext_row apart, merge individual expressions
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* into the destination ResTargets. XXX this approach
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* cannot work for general row expressions as sources.
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*/
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if (list_length($2) != list_length($5))
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ereport(ERROR,
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(errcode(ERRCODE_SYNTAX_ERROR),
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errmsg("number of columns does not match number of values")));
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forboth(col_cell, $2, val_cell, $5)
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{
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ResTarget *res_col = (ResTarget *) lfirst(col_cell);
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Node *res_val = (Node *) lfirst(val_cell);
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res_col->val = res_val;
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}
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$$ = $2;
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}
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;
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set_target:
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ColId opt_indirection
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{
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$$ = makeNode(ResTarget);
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$$->name = $1;
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$$->indirection = $2;
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$$->val = NULL; /* upper production sets this */
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$$->location = @1;
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}
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;
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set_target_list:
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set_target { $$ = list_make1($1); }
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| set_target_list ',' set_target { $$ = lappend($1,$3); }
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;
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@ -5887,83 +5942,20 @@ locked_rels_list:
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values_clause:
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VALUES '(' values_list ')'
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VALUES ctext_row
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{
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SelectStmt *n = makeNode(SelectStmt);
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n->valuesLists = list_make1($3);
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n->valuesLists = list_make1($2);
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$$ = (Node *) n;
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}
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| values_clause ',' '(' values_list ')'
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| values_clause ',' ctext_row
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{
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SelectStmt *n = (SelectStmt *) $1;
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n->valuesLists = lappend(n->valuesLists, $4);
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n->valuesLists = lappend(n->valuesLists, $3);
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$$ = (Node *) n;
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}
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;
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values_list: values_item { $$ = list_make1($1); }
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| values_list ',' values_item { $$ = lappend($1, $3); }
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;
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values_item:
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a_expr { $$ = (Node *) $1; }
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| DEFAULT { $$ = (Node *) makeNode(SetToDefault); }
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;
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update_target_lists_list:
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update_target_lists_el { $$ = $1; }
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| update_target_lists_list ',' update_target_lists_el { $$ = list_concat($1, $3); }
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;
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update_target_lists_el:
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'(' update_col_list ')' '=' '(' update_value_list ')'
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{
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ListCell *col_cell;
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ListCell *val_cell;
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if (list_length($2) != list_length($6))
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{
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ereport(ERROR,
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(errcode(ERRCODE_SYNTAX_ERROR),
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errmsg("number of columns does not match to number of values")));
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}
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for (col_cell = list_head($2), val_cell = list_head($6);
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col_cell != NULL && val_cell != NULL;
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col_cell = lnext(col_cell), val_cell = lnext(val_cell))
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{
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/* merge update_value_list with update_col_list */
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ResTarget *res_col = (ResTarget *) lfirst(col_cell);
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Node *res_val = (Node *) lfirst(val_cell);
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res_col->val = res_val;
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}
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$$ = $2;
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}
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;
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update_col_list:
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update_col_list_el { $$ = list_make1($1); }
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| update_col_list ',' update_col_list_el { $$ = lappend($1, $3); }
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;
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update_col_list_el:
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ColId opt_indirection
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{
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$$ = makeNode(ResTarget);
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$$->name = $1;
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$$->indirection = $2;
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$$->val = NULL;
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$$->location = @1;
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}
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;
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update_value_list:
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values_item { $$ = list_make1($1); }
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| update_value_list ',' values_item { $$ = lappend($1, $3); }
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;
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/*****************************************************************************
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*
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@ -8232,10 +8224,35 @@ opt_asymmetric: ASYMMETRIC
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| /*EMPTY*/
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;
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/*
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* The SQL spec defines "contextually typed value expressions" and
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* "contextually typed row value constructors", which for our purposes
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* are the same as "a_expr" and "row" except that DEFAULT can appear at
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* the top level.
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*/
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ctext_expr:
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a_expr { $$ = (Node *) $1; }
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| DEFAULT { $$ = (Node *) makeNode(SetToDefault); }
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;
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ctext_expr_list:
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ctext_expr { $$ = list_make1($1); }
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| ctext_expr_list ',' ctext_expr { $$ = lappend($1, $3); }
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;
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/*
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* We should allow ROW '(' ctext_expr_list ')' too, but that seems to require
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* making VALUES a fully reserved word, which will probably break more apps
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* than allowing the noise-word is worth.
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*/
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ctext_row: '(' ctext_expr_list ')' { $$ = $2; }
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;
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/*****************************************************************************
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*
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* target lists for SELECT, UPDATE, INSERT
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* target list for SELECT
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*
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*****************************************************************************/
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@ -8275,31 +8292,6 @@ target_el: a_expr AS ColLabel
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}
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;
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update_target_list:
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update_target_el { $$ = list_make1($1); }
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| update_target_list ',' update_target_el { $$ = lappend($1,$3); }
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;
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update_target_el:
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ColId opt_indirection '=' a_expr
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{
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$$ = makeNode(ResTarget);
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$$->name = $1;
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$$->indirection = $2;
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$$->val = (Node *) $4;
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$$->location = @1;
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}
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| ColId opt_indirection '=' DEFAULT
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{
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$$ = makeNode(ResTarget);
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$$->name = $1;
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$$->indirection = $2;
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$$->val = (Node *) makeNode(SetToDefault);
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$$->location = @1;
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}
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;
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/*****************************************************************************
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*
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@ -1,56 +1,85 @@
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--
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-- UPDATE ... SET <col> = DEFAULT;
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-- UPDATE syntax tests
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--
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CREATE TABLE update_test (
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a INT DEFAULT 10,
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b INT
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b INT,
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c TEXT
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);
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INSERT INTO update_test VALUES (5, 10);
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INSERT INTO update_test VALUES (10, 15);
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INSERT INTO update_test VALUES (5, 10, 'foo');
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INSERT INTO update_test(b, a) VALUES (15, 10);
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SELECT * FROM update_test;
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a | b
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----+----
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5 | 10
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10 | 15
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a | b | c
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----+----+-----
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5 | 10 | foo
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10 | 15 |
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(2 rows)
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UPDATE update_test SET a = DEFAULT, b = DEFAULT;
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SELECT * FROM update_test;
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a | b
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----+---
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10 |
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10 |
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a | b | c
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----+---+-----
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10 | | foo
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10 | |
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(2 rows)
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-- aliases for the UPDATE target table
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UPDATE update_test AS t SET b = 10 WHERE t.a = 10;
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SELECT * FROM update_test;
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a | b
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----+----
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10 | 10
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10 | 10
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a | b | c
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----+----+-----
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10 | 10 | foo
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10 | 10 |
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(2 rows)
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UPDATE update_test t SET b = t.b + 10 WHERE t.a = 10;
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SELECT * FROM update_test;
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a | b
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----+----
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10 | 20
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10 | 20
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a | b | c
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----+----+-----
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10 | 20 | foo
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10 | 20 |
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(2 rows)
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--
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-- Test VALUES in FROM
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--
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UPDATE update_test SET a=v.i FROM (VALUES(100, 20)) AS v(i, j)
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WHERE update_test.b = v.j;
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WHERE update_test.b = v.j;
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SELECT * FROM update_test;
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a | b
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-----+----
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100 | 20
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100 | 20
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a | b | c
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-----+----+-----
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100 | 20 | foo
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100 | 20 |
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(2 rows)
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--
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-- Test multiple-set-clause syntax
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--
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UPDATE update_test SET (c,b,a) = ('bugle', b+11, DEFAULT) WHERE c = 'foo';
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SELECT * FROM update_test;
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a | b | c
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-----+----+-------
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100 | 20 |
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10 | 31 | bugle
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(2 rows)
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UPDATE update_test SET (c,b) = ('car', a+b), a = a + 1 WHERE a = 10;
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SELECT * FROM update_test;
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a | b | c
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-----+----+-----
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100 | 20 |
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11 | 41 | car
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(2 rows)
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-- fail, multi assignment to same column:
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UPDATE update_test SET (c,b) = ('car', a+b), b = a + 1 WHERE a = 10;
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ERROR: multiple assignments to same column "b"
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-- XXX this should work, but doesn't yet:
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UPDATE update_test SET (a,b) = (select a,b FROM update_test where c = 'foo')
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WHERE a = 10;
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ERROR: syntax error at or near "select"
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LINE 1: UPDATE update_test SET (a,b) = (select a,b FROM update_test ...
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^
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-- if an alias for the target table is specified, don't allow references
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-- to the original table name
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BEGIN;
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@ -1,14 +1,15 @@
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--
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-- UPDATE ... SET <col> = DEFAULT;
|
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-- UPDATE syntax tests
|
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--
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CREATE TABLE update_test (
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a INT DEFAULT 10,
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b INT
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b INT,
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c TEXT
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);
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INSERT INTO update_test VALUES (5, 10);
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INSERT INTO update_test VALUES (10, 15);
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INSERT INTO update_test VALUES (5, 10, 'foo');
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INSERT INTO update_test(b, a) VALUES (15, 10);
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SELECT * FROM update_test;
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@ -30,10 +31,25 @@ SELECT * FROM update_test;
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--
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UPDATE update_test SET a=v.i FROM (VALUES(100, 20)) AS v(i, j)
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WHERE update_test.b = v.j;
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WHERE update_test.b = v.j;
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|
||||
SELECT * FROM update_test;
|
||||
|
||||
--
|
||||
-- Test multiple-set-clause syntax
|
||||
--
|
||||
|
||||
UPDATE update_test SET (c,b,a) = ('bugle', b+11, DEFAULT) WHERE c = 'foo';
|
||||
SELECT * FROM update_test;
|
||||
UPDATE update_test SET (c,b) = ('car', a+b), a = a + 1 WHERE a = 10;
|
||||
SELECT * FROM update_test;
|
||||
-- fail, multi assignment to same column:
|
||||
UPDATE update_test SET (c,b) = ('car', a+b), b = a + 1 WHERE a = 10;
|
||||
|
||||
-- XXX this should work, but doesn't yet:
|
||||
UPDATE update_test SET (a,b) = (select a,b FROM update_test where c = 'foo')
|
||||
WHERE a = 10;
|
||||
|
||||
-- if an alias for the target table is specified, don't allow references
|
||||
-- to the original table name
|
||||
BEGIN;
|
||||
|
||||
Loading…
x
Reference in New Issue
Block a user