Dynamic cursors and WHERE clause Teradata

Question

I'm trying to write a procedure where the databasename is dynamic and is taken from a where clause. So far I have got this:

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;

I would need to add something like this now:

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

Any ideas? Can I add this when I call the procedure?

Answer 1

Sounds like you just need a variable to make this more dynamic:

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;

I'm not sure what you were trying to do with firstpart||envname, but this should get you in the ballpark. Essentially you just need to craft a sql statement that makes your dbname variable and then use that in your second query.