具有不同返回值的函数 DB2 [英] Function with different returns DB2
问题描述
您好,我有这个功能:
CREATE or replace FUNCTION Tablereturn (SWITCHER INTEGER)
RETURNS TABLE (Test CHAR(9),
tester INTEGER
)
LANGUAGE SQL
CONTAINS SQL
DETERMINISTIC
NO EXTERNAL ACTION
BEGIN
DECLARE SELECT1, SELECT2 VARCHAR(1024);
set select1 ='SELECT TEST, TESTER FROM TESTTAB';
set select2 ='SELECT DUMMY, JAR, BRAND FROM TESTTAB';
IF (SWITCHER = '1') THEN return select1;
ELSEIF (SWITCHER = '2') THEN return select2;
END IF;
RETURN TABLE;
END@
打电话是
select TEST from TABLE(Tablereturn(1))@
或
select JAR from TABLE(Tablereturn(2))@
问题是,它不起作用.编译器说返回意外的令牌SELECT1"后就在那里.我希望能够将其作为表格调用,并根据需要从调用中选择值.我不能只将它作为一个过程调用,并将选择作为返回,因为我需要将选择作为一个表来使用,并在更大的选择中更改返回的输出.我可以在函数中使用 EXECUTE IMMEDIATE 吗?
The problem is, that it doesn't work. Compiler says that after return the unexpected Token "SELECT1" is there. I want to be able to call it as a table and select values as I need them from the call. I can't just call it as a procedure with the select as return, since I need to work with the select as a table and change the returned output in a bigger select. Can I have EXECUTE IMMEDIATE in a function?
有什么想法吗?另一个问题是,我怎样才能让函数返回不同的表?select2 返回 3 个值,而 select1 只返回 2 个.
Any ideas? The other question is, how can I make the function return different tables? The select2 returns 3 values while select1 returns only 2.
感谢您的帮助.
推荐答案
RETURN 语句必须是函数的最后一个语句.有一类称为流水线"的函数,您可以在其中使用if then else"逻辑.像这样:
RETURN statement must be the last statement of the function. There is a class of functions called 'pipelined' where you can use 'if then else' logic. Like this:
CREATE OR REPLACE FUNCTION TEST_PIPELINED(P_CHOICE INT)
RETURNS TABLE (R_COL1 VARCHAR(128), R_COL2 VARCHAR(128))
BEGIN
DECLARE SQLSTATE CHAR(5);
DECLARE L_COL1 VARCHAR(128);
DECLARE L_COL2 VARCHAR(128);
DECLARE c1 CURSOR FOR S1;
IF P_CHOICE=1 THEN
PREPARE S1 FROM 'SELECT COLNAME, COLNO FROM SYSCAT.COLUMNS FETCH FIRST 10 ROWS ONLY';
ELSE
PREPARE S1 FROM 'SELECT TABNAME, OWNER FROM SYSCAT.TABLES FETCH FIRST 10 ROWS ONLY';
END IF;
OPEN c1;
L1: LOOP
FETCH c1 INTO L_COL1, L_COL2;
IF SQLSTATE<>'00000' THEN LEAVE L1; END IF;
PIPE(L_COL1, L_COL2);
END LOOP L1;
CLOSE c1;
RETURN;
END@
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