Question

我正在尝试编写一个程序，其中databasename是动态的，并且取自where子句。到目前为止，我已经得到了这个：

CREATE PROCEDURE Test

(IN DBName VARCHAR(100), OUT RowCount DEC(10,2))

BEGIN

DECLARE SqlStr VARCHAR(1000);

DECLARE C1 CURSOR FOR S1;

SET SqlStr = 'SELECT count(*) FROM '|| DBNAME || '.MyTable ';

PREPARE S1 FROM SqlStr;

OPEN C1 USING DBName;

FETCH C1 INTO RowCount;

CLOSE C1;

END;

我现在需要添加这样的东西：

WHERE DBName = (SELECT 'firstpart||EnvName||' FROM EnvTable 
WHERE EnvName = (SELECT EnvName FROM EnvTable WHERE Flag = 1 AND Priority = (SELECT MIN(Priority) FROM EnvTable))

有什么想法吗？我可以在调用程序时添加它吗？

Answer 1

听起来你只需要一个变量来使它更具动态性：

CREATE PROCEDURE Test

(OUT RowCount DEC(10,2))

BEGIN

    DECLARE SqlStr VARCHAR(1000);
    DECLARE DBName VARCHAR(100);
    DECLARE C1 CURSOR FOR S1;

    /*Get your DBName variable loaded using SELECT INTO*/   
    SELECT 'firstpart' || EnvName INTO DBName
    FROM EnvTable 
    WHERE Flag = 1 AND Priority = (SELECT MIN(Priority) FROM EnvTable);

    /*and continue what you were doing*/
    SET SqlStr = 'SELECT count(*) FROM '|| DBName || '.MyTable ';

    PREPARE S1 FROM SqlStr;

    OPEN C1 USING DBName;

        FETCH C1 INTO RowCount;

    CLOSE C1;

END;

我不确定你试图用firstpart||envname做什么，但是这应该会让你陷入困境。基本上你只需要制作一个sql语句来制作你的dbname变量，然后在第二个查询中使用它。

动态游标和WHERE子句Teradata

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