Synopsis
Use the CREATE CAST statement to create a cast.
Syntax
Grammar
Diagramcreate_cast ::= create_cast_with_function
| create_cast_without_function
| create_cast_with_inout
create_cast_with_function ::= CREATE CAST ( cast_signature ) WITH
FUNCTION subprogram_name
[ ( subprogram_signature ) ]
[ AS ASSIGNMENT | AS IMPLICIT ]
create_cast_without_function ::= CREATE CAST ( cast_signature )
WITHOUT FUNCTION
[ AS ASSIGNMENT | AS IMPLICIT ]
create_cast_with_inout ::= CREATE CAST ( cast_signature ) WITH INOUT
[ AS ASSIGNMENT | AS IMPLICIT ]
cast_signature ::= source_type AS target_type
Semantics
See the semantics of each option in the [PostgreSQL docs][postgresql-docs-create-cast].
Examples
WITH FUNCTION example.
yugabyte=# CREATE FUNCTION sql_to_date(integer) RETURNS date AS $$
SELECT $1::text::date
$$ LANGUAGE SQL IMMUTABLE STRICT;
yugabyte=# CREATE CAST (integer AS date) WITH FUNCTION sql_to_date(integer) AS ASSIGNMENT;
yugabyte=# SELECT CAST (3 AS date);
WITHOUT FUNCTION example.
yugabyte=# CREATE TYPE myfloat4;
yugabyte=# CREATE FUNCTION myfloat4_in(cstring) RETURNS myfloat4
LANGUAGE internal IMMUTABLE STRICT PARALLEL SAFE AS 'float4in';
yugabyte=# CREATE FUNCTION myfloat4_out(myfloat4) RETURNS cstring
LANGUAGE internal IMMUTABLE STRICT PARALLEL SAFE AS 'float4out';
yugabyte=# CREATE TYPE myfloat4 (
INPUT = myfloat4_in,
OUTPUT = myfloat4_out,
LIKE = float4
);
yugabyte=# SELECT CAST('3.14'::myfloat4 AS float4);
yugabyte=# CREATE CAST (myfloat4 AS float4) WITHOUT FUNCTION;
yugabyte=# SELECT CAST('3.14'::myfloat4 AS float4);
WITH INOUT example.
yugabyte=# CREATE TYPE myint4;
yugabyte=# CREATE FUNCTION myint4_in(cstring) RETURNS myint4
LANGUAGE internal IMMUTABLE STRICT PARALLEL SAFE AS 'int4in';
yugabyte=# CREATE FUNCTION myint4_out(myint4) RETURNS cstring
LANGUAGE internal IMMUTABLE STRICT PARALLEL SAFE AS 'int4out';
yugabyte=# CREATE TYPE myint4 (
INPUT = myint4_in,
OUTPUT = myint4_out,
LIKE = int4
);
yugabyte=# SELECT CAST('2'::myint4 AS int4);
yugabyte=# CREATE CAST (myint4 AS int4) WITH INOUT;
yugabyte=# SELECT CAST('2'::myint4 AS int4);