PostgreSQL ALTER TABLE(EN)

Name

ALTER TABLE -- change the definition of a table

Synopsis

ALTER TABLE [ ONLY ] name [ * ]    action [, ... ]ALTER TABLE [ ONLY ] name [ * ]    RENAME [ COLUMN ] column TO new_columnALTER TABLE name    RENAME TO new_nameALTER TABLE name    SET SCHEMA new_schemawhere action is one of:    ADD [ COLUMN ] column data_type [ COLLATE collation ] [ column_constraint [ ... ] ]    DROP [ COLUMN ] [ IF EXISTS ] column [ RESTRICT | CASCADE ]    ALTER [ COLUMN ] column [ SET DATA ] TYPE data_type [ COLLATE collation ] [ USING expression ]    ALTER [ COLUMN ] column SET DEFAULT expression    ALTER [ COLUMN ] column DROP DEFAULT    ALTER [ COLUMN ] column { SET | DROP } NOT NULL    ALTER [ COLUMN ] column SET STATISTICS integer    ALTER [ COLUMN ] column SET ( attribute_option = value [, ... ] )    ALTER [ COLUMN ] column RESET ( attribute_option [, ... ] )    ALTER [ COLUMN ] column SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }    ADD table_constraint [ NOT VALID ]    ADD table_constraint_using_index    VALIDATE CONSTRAINT constraint_name    DROP CONSTRAINT [ IF EXISTS ]  constraint_name [ RESTRICT | CASCADE ]    DISABLE TRIGGER [ trigger_name | ALL | USER ]    ENABLE TRIGGER [ trigger_name | ALL | USER ]    ENABLE REPLICA TRIGGER trigger_name    ENABLE ALWAYS TRIGGER trigger_name    DISABLE RULE rewrite_rule_name    ENABLE RULE rewrite_rule_name    ENABLE REPLICA RULE rewrite_rule_name    ENABLE ALWAYS RULE rewrite_rule_name    CLUSTER ON index_name    SET WITHOUT CLUSTER    SET WITH OIDS    SET WITHOUT OIDS    SET ( storage_parameter = value [, ... ] )    RESET ( storage_parameter [, ... ] )    INHERIT parent_table    NO INHERIT parent_table    OF type_name    NOT OF    OWNER TO new_owner    SET TABLESPACE new_tablespaceand table_constraint_using_index is:    [ CONSTRAINT constraint_name ]    { UNIQUE | PRIMARY KEY } USING INDEX index_name    [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]

Examples

To add a column of type varchar to a table:

ALTER TABLE distributors ADD COLUMN address varchar(30);

To drop a column from a table:

ALTER TABLE distributors DROP COLUMN address RESTRICT;

To change the types of two existing columns in one operation:

ALTER TABLE distributors    ALTER COLUMN address TYPE varchar(80),    ALTER COLUMN name TYPE varchar(100);

To change an integer column containing UNIX timestamps to timestamp with time zone via a USING clause:

ALTER TABLE foo    ALTER COLUMN foo_timestamp SET DATA TYPE timestamp with time zone    USING        timestamp with time zone 'epoch' + foo_timestamp * interval '1 second';

The same, when the column has a default expression that won't automatically cast to the new data type:

ALTER TABLE foo    ALTER COLUMN foo_timestamp DROP DEFAULT,    ALTER COLUMN foo_timestamp TYPE timestamp with time zone    USING        timestamp with time zone 'epoch' + foo_timestamp * interval '1 second',    ALTER COLUMN foo_timestamp SET DEFAULT now();

To rename an existing column:

ALTER TABLE distributors RENAME COLUMN address TO city;

To rename an existing table:

ALTER TABLE distributors RENAME TO suppliers;

To add a not-null constraint to a column:

ALTER TABLE distributors ALTER COLUMN street SET NOT NULL;

To remove a not-null constraint from a column:

ALTER TABLE distributors ALTER COLUMN street DROP NOT NULL;

To add a check constraint to a table and all its children:

ALTER TABLE distributors ADD CONSTRAINT zipchk CHECK (char_length(zipcode) = 5);

To remove a check constraint from a table and all its children:

ALTER TABLE distributors DROP CONSTRAINT zipchk;

To remove a check constraint from a table only:

ALTER TABLE ONLY distributors DROP CONSTRAINT zipchk;

(The check constraint remains in place for any child tables.)

To add a foreign key constraint to a table:

ALTER TABLE distributors ADD CONSTRAINT distfk FOREIGN KEY (address) REFERENCES addresses (address) MATCH FULL;

To add a (multicolumn) unique constraint to a table:

ALTER TABLE distributors ADD CONSTRAINT dist_id_zipcode_key UNIQUE (dist_id, zipcode);

To add an automatically named primary key constraint to a table, noting that a table can only ever have one primary key:

ALTER TABLE distributors ADD PRIMARY KEY (dist_id);

To move a table to a different tablespace:

ALTER TABLE distributors SET TABLESPACE fasttablespace;

To move a table to a different schema:

ALTER TABLE myschema.distributors SET SCHEMA yourschema;

To recreate a primary key constraint, without blocking updates while the index is rebuilt:

CREATE UNIQUE INDEX CONCURRENTLY dist_id_temp_idx ON distributors (dist_id);ALTER TABLE distributors DROP CONSTRAINT distributors_pkey,    ADD CONSTRAINT distributors_pkey PRIMARY KEY USING INDEX dist_id_temp_idx;

 

http://www.postgresql.org/docs/current/static/sql-altertable.html