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Commit 091fe037 authored by Tom Lane's avatar Tom Lane
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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.
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doc/src/sgml/ref/update.sgml
+ 24
− 7
View file @ 091fe037
<!--
$PostgreSQL: pgsql/doc/src/sgml/ref/update.sgml,v 1.39 2006/09/02 20:34:47 momjian Exp $
$PostgreSQL: pgsql/doc/src/sgml/ref/update.sgml,v 1.40 2006/09/03 22:37:05 tgl Exp $
PostgreSQL documentation
-->
......@@ -21,8 +21,8 @@ PostgreSQL documentation
<refsynopsisdiv>
<synopsis>
UPDATE [ ONLY ] <replaceable class="PARAMETER">table</replaceable> [ [ AS ] <replaceable class="parameter">alias</replaceable> ]
[ SET <replaceable class="PARAMETER">column</replaceable> = { <replaceable class="PARAMETER">expression</replaceable> | DEFAULT } [, ...] |
SET ( <replaceable class="PARAMETER">column</replaceable> [, ...] ) = ( { <replaceable class="PARAMETER">expression</replaceable> | DEFAULT } [, ...] ) [, ...] ]
SET { <replaceable class="PARAMETER">column</replaceable> = { <replaceable class="PARAMETER">expression</replaceable> | DEFAULT } |
( <replaceable class="PARAMETER">column</replaceable> [, ...] ) = ( { <replaceable class="PARAMETER">expression</replaceable> | DEFAULT } [, ...] ) } [, ...]
[ FROM <replaceable class="PARAMETER">fromlist</replaceable> ]
[ WHERE <replaceable class="PARAMETER">condition</replaceable> ]
[ RETURNING * | <replaceable class="parameter">output_expression</replaceable> [ AS <replaceable class="parameter">output_name</replaceable> ] [, ...] ]
......@@ -251,10 +251,6 @@ UPDATE films SET kind = 'Dramatic' WHERE kind = 'Drama';
<programlisting>
UPDATE weather SET temp_lo = temp_lo+1, temp_hi = temp_lo+15, prcp = DEFAULT
WHERE city = 'San Francisco' AND date = '2003-07-03';
</programlisting>
<programlisting>
UPDATE weather SET (temp_lo, temp_hi, prcp) = (temp_lo+1, temp_lo+15, DEFAULT)
WHERE city = 'San Francisco' AND date = '2003-07-03';
</programlisting>
</para>
......@@ -268,6 +264,14 @@ UPDATE weather SET temp_lo = temp_lo+1, temp_hi = temp_lo+15, prcp = DEFAULT
</programlisting>
</para>
<para>
Use the alternative column-list syntax to do the same update:
<programlisting>
UPDATE weather SET (temp_lo, temp_hi, prcp) = (temp_lo+1, temp_lo+15, DEFAULT)
WHERE city = 'San Francisco' AND date = '2003-07-03';
</programlisting>
</para>
<para>
Increment the sales count of the salesperson who manages the
account for Acme Corporation, using the <literal>FROM</literal>
......@@ -316,6 +320,19 @@ COMMIT;
are <productname>PostgreSQL</productname> extensions.
</para>
<para>
According to the standard, the column-list syntax should allow a list
of columns to be assigned from a single row-valued expression, such
as a sub-select:
<programlisting>
UPDATE accounts SET (contact_last_name, contact_first_name) =
(SELECT last_name, first_name FROM salesmen
WHERE salesmen.id = accounts.sales_id);
</programlisting>
This is not currently implemented &mdash; the source must be a list
of independent expressions.
</para>
<para>
Some other database systems offer a <literal>FROM</> option in which
the target table is supposed to be listed again within <literal>FROM</>.
......
src/backend/parser/gram.y
+ 96
− 104
View file @ 091fe037
......@@ -11,7 +11,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/parser/gram.y,v 2.564 2006/09/03 03:19:44 momjian Exp $
* $PostgreSQL: pgsql/src/backend/parser/gram.y,v 2.565 2006/09/03 22:37:05 tgl Exp $
*
* HISTORY
* AUTHOR DATE MAJOR EVENT
......@@ -236,9 +236,9 @@ static void doNegateFloat(Value *v);
name_list from_clause from_list opt_array_bounds
qualified_name_list any_name any_name_list
any_operator expr_list attrs
target_list update_col_list update_target_list
update_value_list set_opt insert_column_list
values_list def_list indirection opt_indirection
target_list insert_column_list set_target_list
set_clause_list set_clause multiple_set_clause
ctext_expr_list ctext_row def_list indirection opt_indirection
group_clause TriggerFuncArgs select_limit
opt_select_limit opclass_item_list
transaction_mode_list_or_empty
......@@ -299,7 +299,7 @@ static void doNegateFloat(Value *v);
%type <list> when_clause_list
%type <ival> sub_type
%type <list> OptCreateAs CreateAsList
%type <node> CreateAsElement values_item
%type <node> CreateAsElement ctext_expr
%type <value> NumericOnly FloatOnly IntegerOnly
%type <alias> alias_clause
%type <sortby> sortby
......@@ -308,8 +308,7 @@ static void doNegateFloat(Value *v);
%type <jexpr> joined_table
%type <range> relation_expr
%type <range> relation_expr_opt_alias
%type <target> target_el update_target_el update_col_list_el insert_column_item
%type <list> update_target_lists_list update_target_lists_el
%type <target> target_el single_set_clause set_target insert_column_item
%type <typnam> Typename SimpleTypename ConstTypename
GenericType Numeric opt_float
......@@ -5488,7 +5487,7 @@ opt_nowait: NOWAIT { $$ = TRUE; }
*****************************************************************************/
UpdateStmt: UPDATE relation_expr_opt_alias
SET set_opt
SET set_clause_list
from_clause
where_clause
returning_clause
......@@ -5503,9 +5502,65 @@ UpdateStmt: UPDATE relation_expr_opt_alias
}
;
set_opt:
update_target_list { $$ = $1; }
| update_target_lists_list { $$ = $1; }
set_clause_list:
set_clause { $$ = $1; }
| set_clause_list ',' set_clause { $$ = list_concat($1,$3); }
;
set_clause:
single_set_clause { $$ = list_make1($1); }
| multiple_set_clause { $$ = $1; }
;
single_set_clause:
set_target '=' ctext_expr
{
$$ = $1;
$$->val = (Node *) $3;
}
;
multiple_set_clause:
'(' set_target_list ')' '=' ctext_row
{
ListCell *col_cell;
ListCell *val_cell;
/*
* Break the ctext_row apart, merge individual expressions
* into the destination ResTargets. XXX this approach
* cannot work for general row expressions as sources.
*/
if (list_length($2) != list_length($5))
ereport(ERROR,
(errcode(ERRCODE_SYNTAX_ERROR),
errmsg("number of columns does not match number of values")));
forboth(col_cell, $2, val_cell, $5)
{
ResTarget *res_col = (ResTarget *) lfirst(col_cell);
Node *res_val = (Node *) lfirst(val_cell);
res_col->val = res_val;
}
$$ = $2;
}
;
set_target:
ColId opt_indirection
{
$$ = makeNode(ResTarget);
$$->name = $1;
$$->indirection = $2;
$$->val = NULL; /* upper production sets this */
$$->location = @1;
}
;
set_target_list:
set_target { $$ = list_make1($1); }
| set_target_list ',' set_target { $$ = lappend($1,$3); }
;
......@@ -5887,83 +5942,20 @@ locked_rels_list:
values_clause:
VALUES '(' values_list ')'
VALUES ctext_row
{
SelectStmt *n = makeNode(SelectStmt);
n->valuesLists = list_make1($3);
n->valuesLists = list_make1($2);
$$ = (Node *) n;
}
| values_clause ',' '(' values_list ')'
| values_clause ',' ctext_row
{
SelectStmt *n = (SelectStmt *) $1;
n->valuesLists = lappend(n->valuesLists, $4);
n->valuesLists = lappend(n->valuesLists, $3);
$$ = (Node *) n;
}
;
values_list: values_item { $$ = list_make1($1); }
| values_list ',' values_item { $$ = lappend($1, $3); }
;
values_item:
a_expr { $$ = (Node *) $1; }
| DEFAULT { $$ = (Node *) makeNode(SetToDefault); }
;
update_target_lists_list:
update_target_lists_el { $$ = $1; }
| update_target_lists_list ',' update_target_lists_el { $$ = list_concat($1, $3); }
;
update_target_lists_el:
'(' update_col_list ')' '=' '(' update_value_list ')'
{
ListCell *col_cell;
ListCell *val_cell;
if (list_length($2) != list_length($6))
{
ereport(ERROR,
(errcode(ERRCODE_SYNTAX_ERROR),
errmsg("number of columns does not match to number of values")));
}
for (col_cell = list_head($2), val_cell = list_head($6);
col_cell != NULL && val_cell != NULL;
col_cell = lnext(col_cell), val_cell = lnext(val_cell))
{
/* merge update_value_list with update_col_list */
ResTarget *res_col = (ResTarget *) lfirst(col_cell);
Node *res_val = (Node *) lfirst(val_cell);
res_col->val = res_val;
}
$$ = $2;
}
;
update_col_list:
update_col_list_el { $$ = list_make1($1); }
| update_col_list ',' update_col_list_el { $$ = lappend($1, $3); }
;
update_col_list_el:
ColId opt_indirection
{
$$ = makeNode(ResTarget);
$$->name = $1;
$$->indirection = $2;
$$->val = NULL;
$$->location = @1;
}
;
update_value_list:
values_item { $$ = list_make1($1); }
| update_value_list ',' values_item { $$ = lappend($1, $3); }
;
/*****************************************************************************
*
......@@ -8232,10 +8224,35 @@ opt_asymmetric: ASYMMETRIC
| /*EMPTY*/
;
/*
* The SQL spec defines "contextually typed value expressions" and
* "contextually typed row value constructors", which for our purposes
* are the same as "a_expr" and "row" except that DEFAULT can appear at
* the top level.
*/
ctext_expr:
a_expr { $$ = (Node *) $1; }
| DEFAULT { $$ = (Node *) makeNode(SetToDefault); }
;
ctext_expr_list:
ctext_expr { $$ = list_make1($1); }
| ctext_expr_list ',' ctext_expr { $$ = lappend($1, $3); }
;
/*
* We should allow ROW '(' ctext_expr_list ')' too, but that seems to require
* making VALUES a fully reserved word, which will probably break more apps
* than allowing the noise-word is worth.
*/
ctext_row: '(' ctext_expr_list ')' { $$ = $2; }
;
/*****************************************************************************
*
* target lists for SELECT, UPDATE, INSERT
* target list for SELECT
*
*****************************************************************************/
......@@ -8275,31 +8292,6 @@ target_el: a_expr AS ColLabel
}
;
update_target_list:
update_target_el { $$ = list_make1($1); }
| update_target_list ',' update_target_el { $$ = lappend($1,$3); }
;
update_target_el:
ColId opt_indirection '=' a_expr
{
$$ = makeNode(ResTarget);
$$->name = $1;
$$->indirection = $2;
$$->val = (Node *) $4;
$$->location = @1;
}
| ColId opt_indirection '=' DEFAULT
{
$$ = makeNode(ResTarget);
$$->name = $1;
$$->indirection = $2;
$$->val = (Node *) makeNode(SetToDefault);
$$->location = @1;
}
;
/*****************************************************************************
*
......
src/test/regress/expected/update.out
+ 54
− 25
View file @ 091fe037
--
-- UPDATE ... SET <col> = DEFAULT;
-- UPDATE syntax tests
--
CREATE TABLE update_test (
a INT DEFAULT 10,
b INT
b INT,
c TEXT
);
INSERT INTO update_test VALUES (5, 10);
INSERT INTO update_test VALUES (10, 15);
INSERT INTO update_test VALUES (5, 10, 'foo');
INSERT INTO update_test(b, a) VALUES (15, 10);
SELECT * FROM update_test;
a | b
----+----
5 | 10
10 | 15
a | b | c
----+----+-----
5 | 10 | foo
10 | 15 |
(2 rows)
UPDATE update_test SET a = DEFAULT, b = DEFAULT;
SELECT * FROM update_test;
a | b
----+---
10 |
10 |
a | b | c
----+---+-----
10 | | foo
10 | |
(2 rows)
-- aliases for the UPDATE target table
UPDATE update_test AS t SET b = 10 WHERE t.a = 10;
SELECT * FROM update_test;
a | b
----+----
10 | 10
10 | 10
a | b | c
----+----+-----
10 | 10 | foo
10 | 10 |
(2 rows)
UPDATE update_test t SET b = t.b + 10 WHERE t.a = 10;
SELECT * FROM update_test;
a | b
----+----
10 | 20
10 | 20
a | b | c
----+----+-----
10 | 20 | foo
10 | 20 |
(2 rows)
--
-- Test VALUES in FROM
--
UPDATE update_test SET a=v.i FROM (VALUES(100, 20)) AS v(i, j)
WHERE update_test.b = v.j;
WHERE update_test.b = v.j;
SELECT * FROM update_test;
a | b
-----+----
100 | 20
100 | 20
a | b | c
-----+----+-----
100 | 20 | foo
100 | 20 |
(2 rows)
--
-- Test multiple-set-clause syntax
--
UPDATE update_test SET (c,b,a) = ('bugle', b+11, DEFAULT) WHERE c = 'foo';
SELECT * FROM update_test;
a | b | c
-----+----+-------
100 | 20 |
10 | 31 | bugle
(2 rows)
UPDATE update_test SET (c,b) = ('car', a+b), a = a + 1 WHERE a = 10;
SELECT * FROM update_test;
a | b | c
-----+----+-----
100 | 20 |
11 | 41 | car
(2 rows)
-- fail, multi assignment to same column:
UPDATE update_test SET (c,b) = ('car', a+b), b = a + 1 WHERE a = 10;
ERROR: multiple assignments to same column "b"
-- 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;
ERROR: syntax error at or near "select"
LINE 1: UPDATE update_test SET (a,b) = (select a,b FROM update_test ...
^
-- if an alias for the target table is specified, don't allow references
-- to the original table name
BEGIN;
......
src/test/regress/sql/update.sql
+ 21
− 5
View file @ 091fe037
--
-- UPDATE ... SET <col> = DEFAULT;
-- UPDATE syntax tests
--
CREATE TABLE update_test (
a INT DEFAULT 10,
b INT
b INT,
c TEXT
);
INSERT INTO update_test VALUES (5, 10);
INSERT INTO update_test VALUES (10, 15);
INSERT INTO update_test VALUES (5, 10, 'foo');
INSERT INTO update_test(b, a) VALUES (15, 10);
SELECT * FROM update_test;
......@@ -30,10 +31,25 @@ SELECT * FROM update_test;
--
UPDATE update_test SET a=v.i FROM (VALUES(100, 20)) AS v(i, j)
WHERE update_test.b = v.j;
WHERE update_test.b = v.j;
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;
......
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