[英]Dynamically pass table name to a query db2
我需要從表中執行COUNT,該表是動態生成的並存儲值
嘗試了兩種方法,但均未成功:
SET COUNT = (SELECT COUNT(*) FROM BUILD_FUNCTION_NAME(a,b))
SET NAME = BUILD_FUNCTION_NAME(a,b)
SET COUNT = ( SELECT COUNT(*) FROM NAME)
如果是DB2 for LUW,請嘗試以下操作:
--#SET TERMINATOR @
CREATE OR REPLACE FUNCTION GET_COUNT(P_TABNAME VARCHAR(256))
RETURNS BIGINT
BEGIN
DECLARE V_RC BIGINT;
PREPARE S1 FROM 'SET ? = (SELECT COUNT(1) FROM '||P_TABNAME||')';
EXECUTE S1 INTO V_RC;
RETURN V_RC;
END@
VALUES GET_COUNT('SYSCAT.TABLES')@
VALUES GET_COUNT('SYSCAT.COLUMNS')@
VALUES GET_COUNT('(SELECT 1 FROM SYSCAT.TABLES WHERE TABSCHEMA LIKE ''SYS%'')')@
您甚至可以將任意SELECT
語句作為參數傳遞給函數。
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