在 Snowflake 函数的 where 子句中将 NULL 作为参数传递

Question

我有一个带参数的函数。如果我在 where 子句中将 null 作为参数传递，我希望它返回所有结果，例如

CREATE OR REPLACE FUNCTION ABC(" CUSTCODE" VARCHAR)
RETURNS TABLE ("CUSTOMER_CODE" VARCHAR, CUSTOMERNAME VARCHAR)
LANGUAGE SQL
AS '                                  
   SELECT  CUSTOMER_CODE, CUSTOMERNAME FROM DIM_CUSTOMER
    WHERE  CUSTOMER_CODE = CUSTCODE
';

因此，如果 CUSTCODE 为 NULL 然后带回所有 CUSTOMER_CODE 几乎就像忽略 where 子句

有人能给我指出正确的方向吗？

提前致谢！

里昂

Answer 1

根据 Dai 的评论：

CREATE OR REPLACE TABLE DIM_CUSTOMER(CUSTOMER_CODE text, CUSTOMERNAME text);

INSERT INTO DIM_CUSTOMER VALUES ('one', 'customer one'),('two', 'customer two');

CREATE OR REPLACE FUNCTION ABC(CUSTCODE VARCHAR)
RETURNS TABLE (CUSTOMER_CODE VARCHAR, CUSTOMERNAME VARCHAR)
LANGUAGE SQL
AS '                                  
   SELECT CUSTOMER_CODE, CUSTOMERNAME FROM DIM_CUSTOMER
    WHERE CUSTCODE IS NULL OR CUSTOMER_CODE = CUSTCODE
';

SELECT * FROM TABLE(ABC('one'));

给出：

CUSTOMER_CODE	CUSTOMERNAME
one	customer one

SELECT * FROM TABLE(ABC(null::text));

给出：

CUSTOMER_CODE	CUSTOMERNAME
one	customer one
two	customer two