<!--
-$PostgreSQL: pgsql/doc/src/sgml/ref/alter_table.sgml,v 1.106 2009/05/03 20:45:43 tgl Exp $
+$PostgreSQL: pgsql/doc/src/sgml/ref/alter_table.sgml,v 1.107 2009/07/20 02:42:27 adunstan Exp $
PostgreSQL documentation
-->
where <replaceable class="PARAMETER">action</replaceable> is one of:
ADD [ COLUMN ] <replaceable class="PARAMETER">column</replaceable> <replaceable class="PARAMETER">type</replaceable> [ <replaceable class="PARAMETER">column_constraint</replaceable> [ ... ] ]
- DROP [ COLUMN ] <replaceable class="PARAMETER">column</replaceable> [ RESTRICT | CASCADE ]
+ DROP [ COLUMN ] [ IF EXISTS ] <replaceable class="PARAMETER">column</replaceable> [ RESTRICT | CASCADE ]
ALTER [ COLUMN ] <replaceable class="PARAMETER">column</replaceable> [ SET DATA ] TYPE <replaceable class="PARAMETER">type</replaceable> [ USING <replaceable class="PARAMETER">expression</replaceable> ]
ALTER [ COLUMN ] <replaceable class="PARAMETER">column</replaceable> SET DEFAULT <replaceable class="PARAMETER">expression</replaceable>
ALTER [ COLUMN ] <replaceable class="PARAMETER">column</replaceable> DROP DEFAULT
ALTER [ COLUMN ] <replaceable class="PARAMETER">column</replaceable> SET STATISTICS <replaceable class="PARAMETER">integer</replaceable>
ALTER [ COLUMN ] <replaceable class="PARAMETER">column</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
ADD <replaceable class="PARAMETER">table_constraint</replaceable>
- DROP CONSTRAINT <replaceable class="PARAMETER">constraint_name</replaceable> [ RESTRICT | CASCADE ]
+ DROP CONSTRAINT [ IF EXISTS ] <replaceable class="PARAMETER">constraint_name</replaceable> [ RESTRICT | CASCADE ]
DISABLE TRIGGER [ <replaceable class="PARAMETER">trigger_name</replaceable> | ALL | USER ]
ENABLE TRIGGER [ <replaceable class="PARAMETER">trigger_name</replaceable> | ALL | USER ]
ENABLE REPLICA TRIGGER <replaceable class="PARAMETER">trigger_name</replaceable>
</varlistentry>
<varlistentry>
- <term><literal>DROP COLUMN</literal></term>
+ <term><literal>DROP COLUMN [ IF EXISTS ]</literal></term>
<listitem>
<para>
This form drops a column from a table. Indexes and
dropped as well. You will need to say <literal>CASCADE</> if
anything outside the table depends on the column, for example,
foreign key references or views.
+ If <literal>IF EXISTS</literal> is specified and the column
+ does not exist, no error is thrown. In this case a notice
+ is issued instead.
</para>
</listitem>
</varlistentry>
</varlistentry>
<varlistentry>
- <term><literal>DROP CONSTRAINT</literal></term>
+ <term><literal>DROP CONSTRAINT [ IF EXISTS ]</literal></term>
<listitem>
<para>
This form drops the specified constraint on a table.
+ If <literal>IF EXISTS</literal> is specified and the constraint
+ does not exist, no error is thrown. In this case a notice is issued instead.
</para>
</listitem>
</varlistentry>
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/commands/tablecmds.c,v 1.290 2009/07/16 06:33:42 petere Exp $
+ * $PostgreSQL: pgsql/src/backend/commands/tablecmds.c,v 1.291 2009/07/20 02:42:27 adunstan Exp $
*
*-------------------------------------------------------------------------
*/
Node *newValue);
static void ATExecDropColumn(List **wqueue, Relation rel, const char *colName,
DropBehavior behavior,
- bool recurse, bool recursing);
+ bool recurse, bool recursing,
+ bool missing_ok);
static void ATExecAddIndex(AlteredTableInfo *tab, Relation rel,
IndexStmt *stmt, bool is_rebuild);
static void ATExecAddConstraint(List **wqueue,
static void ATAddForeignKeyConstraint(AlteredTableInfo *tab, Relation rel,
FkConstraint *fkconstraint);
static void ATExecDropConstraint(Relation rel, const char *constrName,
- DropBehavior behavior,
- bool recurse, bool recursing);
+ DropBehavior behavior,
+ bool recurse, bool recursing,
+ bool missing_ok);
static void ATPrepAlterColumnType(List **wqueue,
AlteredTableInfo *tab, Relation rel,
bool recurse, bool recursing,
break;
case AT_DropColumn: /* DROP COLUMN */
ATExecDropColumn(wqueue, rel, cmd->name,
- cmd->behavior, false, false);
+ cmd->behavior, false, false, cmd->missing_ok);
break;
case AT_DropColumnRecurse: /* DROP COLUMN with recursion */
ATExecDropColumn(wqueue, rel, cmd->name,
- cmd->behavior, true, false);
+ cmd->behavior, true, false, cmd->missing_ok);
break;
case AT_AddIndex: /* ADD INDEX */
ATExecAddIndex(tab, rel, (IndexStmt *) cmd->def, false);
ATExecAddConstraint(wqueue, tab, rel, cmd->def, true);
break;
case AT_DropConstraint: /* DROP CONSTRAINT */
- ATExecDropConstraint(rel, cmd->name, cmd->behavior, false, false);
+ ATExecDropConstraint(rel, cmd->name, cmd->behavior,
+ false, false,
+ cmd->missing_ok);
break;
case AT_DropConstraintRecurse: /* DROP CONSTRAINT with recursion */
- ATExecDropConstraint(rel, cmd->name, cmd->behavior, true, false);
+ ATExecDropConstraint(rel, cmd->name, cmd->behavior,
+ true, false,
+ cmd->missing_ok);
break;
case AT_AlterColumnType: /* ALTER COLUMN TYPE */
ATExecAlterColumnType(tab, rel, cmd->name, (TypeName *) cmd->def);
static void
ATExecDropColumn(List **wqueue, Relation rel, const char *colName,
DropBehavior behavior,
- bool recurse, bool recursing)
+ bool recurse, bool recursing,
+ bool missing_ok)
{
HeapTuple tuple;
Form_pg_attribute targetatt;
* get the number of the attribute
*/
tuple = SearchSysCacheAttName(RelationGetRelid(rel), colName);
- if (!HeapTupleIsValid(tuple))
- ereport(ERROR,
- (errcode(ERRCODE_UNDEFINED_COLUMN),
- errmsg("column \"%s\" of relation \"%s\" does not exist",
- colName, RelationGetRelationName(rel))));
+ if (!HeapTupleIsValid(tuple)){
+ if (!missing_ok){
+ ereport(ERROR,
+ (errcode(ERRCODE_UNDEFINED_COLUMN),
+ errmsg("column \"%s\" of relation \"%s\" does not exist",
+ colName, RelationGetRelationName(rel))));
+ }
+ else
+ {
+ ereport(NOTICE,
+ (errmsg("column \"%s\" of relation \"%s\" does not exist, skipping",
+ colName, RelationGetRelationName(rel))));
+ return;
+ }
+ }
targetatt = (Form_pg_attribute) GETSTRUCT(tuple);
attnum = targetatt->attnum;
{
/* Time to delete this child column, too */
ATExecDropColumn(wqueue, childrel, colName,
- behavior, true, true);
+ behavior, true, true,
+ false);
}
else
{
static void
ATExecDropConstraint(Relation rel, const char *constrName,
DropBehavior behavior,
- bool recurse, bool recursing)
+ bool recurse, bool recursing,
+ bool missing_ok)
{
List *children;
ListCell *child;
systable_endscan(scan);
- if (!found)
- ereport(ERROR,
- (errcode(ERRCODE_UNDEFINED_OBJECT),
- errmsg("constraint \"%s\" of relation \"%s\" does not exist",
- constrName, RelationGetRelationName(rel))));
-
+ if (!found){
+ if (!missing_ok){
+ ereport(ERROR,
+ (errcode(ERRCODE_UNDEFINED_OBJECT),
+ errmsg("constraint \"%s\" of relation \"%s\" does not exist",
+ constrName, RelationGetRelationName(rel))));
+ }
+ else
+ {
+ ereport(NOTICE,
+ (errmsg("constraint \"%s\" of relation \"%s\" does not exist, skipping",
+ constrName, RelationGetRelationName(rel))));
+ heap_close(conrel, RowExclusiveLock);
+ return;
+ }
+ }
/*
* Propagate to children as appropriate. Unlike most other ALTER
* routines, we have to do this one level of recursion at a time; we can't
{
/* Time to delete this child constraint, too */
ATExecDropConstraint(childrel, constrName, behavior,
- true, true);
+ true, true,
+ false);
}
else
{
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/nodes/copyfuncs.c,v 1.433 2009/07/16 06:33:42 petere Exp $
+ * $PostgreSQL: pgsql/src/backend/nodes/copyfuncs.c,v 1.434 2009/07/20 02:42:27 adunstan Exp $
*
*-------------------------------------------------------------------------
*/
COPY_NODE_FIELD(def);
COPY_NODE_FIELD(transform);
COPY_SCALAR_FIELD(behavior);
+ COPY_SCALAR_FIELD(missing_ok);
return newnode;
}
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/nodes/equalfuncs.c,v 1.356 2009/07/16 06:33:42 petere Exp $
+ * $PostgreSQL: pgsql/src/backend/nodes/equalfuncs.c,v 1.357 2009/07/20 02:42:27 adunstan Exp $
*
*-------------------------------------------------------------------------
*/
COMPARE_NODE_FIELD(def);
COMPARE_NODE_FIELD(transform);
COMPARE_SCALAR_FIELD(behavior);
+ COMPARE_SCALAR_FIELD(missing_ok);
return true;
}
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/parser/gram.y,v 2.670 2009/07/16 06:33:43 petere Exp $
+ * $PostgreSQL: pgsql/src/backend/parser/gram.y,v 2.671 2009/07/20 02:42:28 adunstan Exp $
*
* HISTORY
* AUTHOR DATE MAJOR EVENT
n->def = (Node *) makeString($6);
$$ = (Node *)n;
}
+ /* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
+ | DROP opt_column IF_P EXISTS ColId opt_drop_behavior
+ {
+ AlterTableCmd *n = makeNode(AlterTableCmd);
+ n->subtype = AT_DropColumn;
+ n->name = $5;
+ n->behavior = $6;
+ n->missing_ok = TRUE;
+ $$ = (Node *)n;
+ }
/* ALTER TABLE <name> DROP [COLUMN] <colname> [RESTRICT|CASCADE] */
| DROP opt_column ColId opt_drop_behavior
{
n->subtype = AT_DropColumn;
n->name = $3;
n->behavior = $4;
+ n->missing_ok = FALSE;
$$ = (Node *)n;
}
/*
n->def = $2;
$$ = (Node *)n;
}
+ /* ALTER TABLE <name> DROP CONSTRAINT IF EXISTS <name> [RESTRICT|CASCADE] */
+ | DROP CONSTRAINT IF_P EXISTS name opt_drop_behavior
+ {
+ AlterTableCmd *n = makeNode(AlterTableCmd);
+ n->subtype = AT_DropConstraint;
+ n->name = $5;
+ n->behavior = $6;
+ n->missing_ok = TRUE;
+ $$ = (Node *)n;
+ }
/* ALTER TABLE <name> DROP CONSTRAINT <name> [RESTRICT|CASCADE] */
| DROP CONSTRAINT name opt_drop_behavior
{
n->subtype = AT_DropConstraint;
n->name = $3;
n->behavior = $4;
+ n->missing_ok = FALSE;
$$ = (Node *)n;
}
/* ALTER TABLE <name> SET WITH OIDS */
* Portions Copyright (c) 1996-2009, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
- * $PostgreSQL: pgsql/src/include/nodes/parsenodes.h,v 1.396 2009/07/16 06:33:45 petere Exp $
+ * $PostgreSQL: pgsql/src/include/nodes/parsenodes.h,v 1.397 2009/07/20 02:42:28 adunstan Exp $
*
*-------------------------------------------------------------------------
*/
* index, constraint, or parent table */
Node *transform; /* transformation expr for ALTER TYPE */
DropBehavior behavior; /* RESTRICT or CASCADE for DROP cases */
+ bool missing_ok; /* skip error if missing? */
} AlterTableCmd;
ERROR: column "name" of relation "gc1" does not exist
-- should work and drop the attribute in all tables
alter table p2 drop column height;
+-- IF EXISTS test
+create table dropColumnExists ();
+alter table dropColumnExists drop column non_existing; --fail
+ERROR: column "non_existing" of relation "dropcolumnexists" does not exist
+alter table dropColumnExists drop column if exists non_existing; --succeed
+NOTICE: column "non_existing" of relation "dropcolumnexists" does not exist, skipping
select relname, attname, attinhcount, attislocal
from pg_class join pg_attribute on (pg_class.oid = pg_attribute.attrelid)
where relname in ('p1','p2','c1','gc1') and attnum > 0 and not attisdropped
ERROR: operator does not exist: boolean <= integer
HINT: No operator matches the given name and argument type(s). You might need to add explicit type casts.
alter table anothertab drop constraint anothertab_chk;
+alter table anothertab drop constraint anothertab_chk; -- fails
+ERROR: constraint "anothertab_chk" of relation "anothertab" does not exist
+alter table anothertab drop constraint IF EXISTS anothertab_chk; -- succeeds
+NOTICE: constraint "anothertab_chk" of relation "anothertab" does not exist, skipping
alter table anothertab alter column atcol1 type boolean
using case when atcol1 % 2 = 0 then true else false end;
select * from anothertab;
alter table dropColumnchild drop column a;
alter table only dropColumnChild drop column b;
+
+
-- these three should work
alter table only dropColumn drop column e;
alter table dropColumnChild drop column c;
-- should work and drop the attribute in all tables
alter table p2 drop column height;
+-- IF EXISTS test
+create table dropColumnExists ();
+alter table dropColumnExists drop column non_existing; --fail
+alter table dropColumnExists drop column if exists non_existing; --succeed
+
select relname, attname, attinhcount, attislocal
from pg_class join pg_attribute on (pg_class.oid = pg_attribute.attrelid)
where relname in ('p1','p2','c1','gc1') and attnum > 0 and not attisdropped
alter table anothertab alter column atcol1 type boolean
using case when atcol1 % 2 = 0 then true else false end; -- fails
alter table anothertab drop constraint anothertab_chk;
+alter table anothertab drop constraint anothertab_chk; -- fails
+alter table anothertab drop constraint IF EXISTS anothertab_chk; -- succeeds
alter table anothertab alter column atcol1 type boolean
using case when atcol1 % 2 = 0 then true else false end;
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