在 postgres 中使用 return 许多具有空值的行的函数
Function in postgres with return many rows with some null value
我对 postgress 的功能没有什么问题。
我有功能:
CREATE OR REPLACE FUNCTION test(
x integer,
y character varying,
z character varying
)
RETURNS TABLE(x1 int, y1 varchar,n1 varchar,z1 varchar) AS
$BODY$
BEGIN
RETURN QUERY
SELECT x,y,null,z FROM example_tab
END;
$BODY$
LANGUAGE plpgsql VOLATILE
COST 100
ROWS 1000;
当我执行这个函数时出现错误:
Error: Returned type unknown does not match expected type character varying in column 3.
SELECT * FROM test(694531020,'t'::varchar,'t'::varchar)
我应该怎么做才能更正 运行 这个查询并执行这个函数???
您应该明确指定 null 的数据类型,例如:
CREATE OR REPLACE FUNCTION test(
x integer,
y character varying,
z character varying
)
RETURNS TABLE(x1 int, y1 varchar,n1 varchar,z1 varchar) AS
$BODY$
BEGIN
RETURN QUERY
SELECT x,y,null::varchar,z FROM example_tab
END;
$BODY$
LANGUAGE plpgsql VOLATILE
COST 100
ROWS 1000;
我对 postgress 的功能没有什么问题。 我有功能:
CREATE OR REPLACE FUNCTION test(
x integer,
y character varying,
z character varying
)
RETURNS TABLE(x1 int, y1 varchar,n1 varchar,z1 varchar) AS
$BODY$
BEGIN
RETURN QUERY
SELECT x,y,null,z FROM example_tab
END;
$BODY$
LANGUAGE plpgsql VOLATILE
COST 100
ROWS 1000;
当我执行这个函数时出现错误:
Error: Returned type unknown does not match expected type character varying in column 3.
SELECT * FROM test(694531020,'t'::varchar,'t'::varchar)
我应该怎么做才能更正 运行 这个查询并执行这个函数???
您应该明确指定 null 的数据类型,例如:
CREATE OR REPLACE FUNCTION test(
x integer,
y character varying,
z character varying
)
RETURNS TABLE(x1 int, y1 varchar,n1 varchar,z1 varchar) AS
$BODY$
BEGIN
RETURN QUERY
SELECT x,y,null::varchar,z FROM example_tab
END;
$BODY$
LANGUAGE plpgsql VOLATILE
COST 100
ROWS 1000;