CREATE SYNONYM
Function
CREATE SYNONYM creates a synonym object. A synonym is an alias of a database object and is used to record the mapping between database object names. You can use synonyms to access associated database objects.
Precautions
- The user of a synonym should be its owner.
- If the schema name is specified, create a synonym in the specified schema. Otherwise create a synonym in the current schema.
- Database objects that can be accessed using synonyms include tables, views, functions, and stored procedures.
- To use synonyms, you must have the required permissions on associated objects.
- The following DML statements support synonyms: SELECT, INSERT, UPDATE, DELETE, EXPLAIN, and CALL.
Syntax
CREATE [ OR REPLACE ] SYNONYM synonym_name
FOR object_name;
Parameter Description
synonym
Specifies the name of the synonym to be created, which can contain the schema name.
Value range: a string. It must comply with the naming convention.
object_name
Specifies the name of an object that is associated (optionally with schema names).
Value range: a string. It must comply with the naming convention.
NOTE:
object_name can be the name of an object that does not exist.
Example
-- Create schema ot.
postgres=# CREATE SCHEMA ot;
-- Create table ot.t1 and its synonym t1.
postgres=# CREATE TABLE ot.t1(id int, name varchar2(10));
postgres=# CREATE OR REPLACE SYNONYM t1 FOR ot.t1;
-- Use synonym t1.
postgres=# SELECT * FROM t1;
postgres=# INSERT INTO t1 VALUES (1, 'ada'), (2, 'bob');
postgres=# UPDATE t1 SET t1.name = 'cici' WHERE t1.id = 2;
-- Create synonym v1 and its associated view ot.v_t1.
postgres=# CREATE SYNONYM v1 FOR ot.v_t1;
postgres=# CREATE VIEW ot.v_t1 AS SELECT * FROM ot.t1;
-- Use synonym v1.
postgres=# SELECT * FROM v1;
-- Create overloaded function ot.add and its synonym add.
postgres=# CREATE OR REPLACE FUNCTION ot.add(a integer, b integer) RETURNS integer AS
$$
SELECT $1 + $2
$$
LANGUAGE sql;
postgres=# CREATE OR REPLACE FUNCTION ot.add(a decimal(5,2), b decimal(5,2)) RETURNS decimal(5,2) AS
$$
SELECT $1 + $2
$$
LANGUAGE sql;
postgres=# CREATE OR REPLACE SYNONYM add FOR ot.add;
-- Use synonym add.
postgres=# SELECT add(1,2);
postgres=# SELECT add(1.2,2.3);
-- Create stored procedure ot.register and its synonym register.
postgres=# CREATE PROCEDURE ot.register(n_id integer, n_name varchar2(10))
SECURITY INVOKER
AS
BEGIN
INSERT INTO ot.t1 VALUES(n_id, n_name);
END;
/
postgres=# CREATE OR REPLACE SYNONYM register FOR ot.register;
-- Use synonym register to invoke the stored procedure.
postgres=# CALL register(3,'mia');
-- Delete the synonym.
postgres=# DROP SYNONYM t1;
postgres=# DROP SYNONYM IF EXISTS v1;
postgres=# DROP SYNONYM IF EXISTS add;
postgres=# DROP SYNONYM register;
postgres=# DROP SCHEMA ot CASCADE;
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