Sybase-用户定义的函数

Question

I have 2 user defined functions which return a table: Lets say them UDF1 and UDF2

select * from UDF1(param1) -> returns 1 result

select * from UDF2(param2) -> returns 1 result

The problem is when i do

select * from UDF1(param1) union all select * from UDF2(param2) -returns only 1 result.

Ideally it should return 2 results as its a union all.

Can someone help me why this behaviour is observed in sybase?

The exact code is as follows: Created function as below:

EXEC SQL. 
CREATE FUNCTION "ZCHECK_4" ( 
  @COL3_VAL smallint 
) 
RETURNS TABLE ( 
  "COL1" varchar(000030), 
  "COL2" varchar(000030), 
  "COL3" smallint 
) AS RETURN SELECT 
  "ZTESTFUNC"."COL1", 
  "ZTESTFUNC"."COL2", 
  "ZTESTFUNC"."COL3" 
FROM "ZTESTFUNC" "ZTESTFUNC" 
WHERE "ZTESTFUNC"."COL3" = @COL3_VAL 
ENDEXEC.

Final Sql view ->Which is returing only 1 row

CREATE VIEW "ZCHECK_5" AS SELECT 
  "ZCHECK_4"."COL1", 
  "ZCHECK_4"."COL2", 
  "ZCHECK_4"."COL3" 
FROM "ZCHECK_4"( 
  CAST( 
    20 AS TINYINT
  ) 
) "ZCHECK_4" 
UNION ALL SELECT 
  "ZCHECK_4"."COL1", 
  "ZCHECK_4"."COL2", 
  "ZCHECK_4"."COL3" 
FROM "ZCHECK_4"( 
  CAST( 
    10 AS TINYINT
  ) 
) "ZCHECK_4"

Note : the underlying table(ZTESTFUNC) has 2 records which I cross validated.

Answer 1

Apparently for a UDF(User Defined Function) ,syntax after a select statement of a function would be ignored by the Sybase compiler.

Consider the below sceanrio:

Select F1 UNION ALL F2 . F1 and F2 being UDF with parameters, the highlighted text wouldn't be compiled in Sybase. It might be a limitation of Sybase.

Note :This is not a case with tables or views where Union all works perfectly fine.