Question

How do you declare variable and set a value which is a return from a query on them later.

Sample Stored Procedure:

DELIMITER $$

CREATE PROCEDURE `sampledb`.`SetVariableEx`()

    BEGIN

        -- declare variable
        DECLARE xVarA INT;                
        DECLARE xVarB INT;      

        -- in this line, i would like to set a value on xVarA which is a COUNT
        -- of record from table SINGLETABLE
        -- i am getting error on this line.
        SELECT xVarA := COUNT(*) FROM SingleTable;

        -- the value of xVarA is added by 1 and set it to xVarB
        SET xVarB = xVarA + 1;

        -- insert the value of xVarB to the table SINGLETABLE
        INSERT INTO SingleTable(SingleColumn) VALUES (xVarB);

        -- lastly, display all records.
        SELECT * FROM SingleTable;

    END$$

DELIMITER ;

how would i do that?

Answer 1

Try the following:

SET xVarA := (SELECT COUNT(*) FROM SingleTable);

However, for this example, have you considered using an auto auto-incrementing value, rather than managing the value yourself?