在MySQL中使用Date参数在存储过程中进行动态查询

Question

I am writing a stored procedure in MySQL with a dynamic query as shown below:

DROP PROCEDURE IF EXISTS test;
DELIMITER //
CREATE PROCEDURE test(
IN STATUS VARCHAR(20),
IN CREATED_ON1 VARCHAR(10)
) 
BEGIN

SET @query="SELECT STATUS, COUNT(*) FROM CONTROL WHERE ID=ID";

IF STATUS IS NOT NULL THEN
 SET @query=CONCAT(@query, " AND STATUS='",STATUS,"'");
END IF;

IF CREATED_ON1 IS NOT NULL THEN
 SET @query=CONCAT(@query, " AND DATE_FORMAT(CREATED_ON,'%d-%m-%Y')>='", 
CREATED_ON1, "'");
END IF;

SET @query=CONCAT(@query, " GROUP BY STATUS");

PREPARE stmt FROM @query;
EXECUTE stmt; 
DEALLOCATE PREPARE stmt;

END //
DELIMITER ;

I intend to rewrite this procedure with the signature shown below. This will provide the right logic in comparing the dates.

DROP PROCEDURE IF EXISTS test;
DELIMITER //
CREATE PROCEDURE test(
IN STATUS VARCHAR(20),
IN CREATED_ON1 DATE
)

The main question is; how do I concatenate the predicate with date to the @query?

Answer 1

Try using a CASE and pass the parameters:

DROP PROCEDURE IF EXISTS test;
DELIMITER //
CREATE PROCEDURE test(
IN IN_STATUS VARCHAR(20),
IN IN_CREATED_ON1 DATE
)

BEGIN
SET @v_and    = ' AND ';
SET @v_where  = ' WHERE ';
SET @v_query  = 'SELECT STATUS, COUNT(*) FROM CONTROL';
SET @v_status = ' STATUS=? ';
SET @v_date   = ' CREATED_ON >= ? ';
SET @v_group  = ' GROUP BY STATUS';

CASE 

WHEN IN_STATUS IS NOT NULL && IN_CREATED_ON1 IS NOT NULL THEN
    SET @v_query = CONCAT(@v_query,@v_where,@v_status,@v_and,@v_date,@v_group);
    PREPARE stmt FROM @v_query;
    EXECUTE stmt USING @IN_STATUS, @IN_CREATED_ON1; 
WHEN IN_STATUS IS NOT NULL THEN
    SET @v_query = CONCAT(@v_query,@v_where,@v_status,@v_group);
    PREPARE stmt FROM @v_query;
    EXECUTE stmt USING @IN_STATUS; 
WHEN IN_CREATED_ON1 IS NOT NULL THEN
    SET @v_query = CONCAT(@v_query,@v_where,@v_date,@v_group);
    PREPARE stmt FROM @v_query;
    EXECUTE stmt USING @IN_CREATED_ON1; 
ELSE
    SET @v_query = CONCAT (@v_query,@v_group);
    PREPARE stmt FROM @v_query;
    EXECUTE stmt; 
END CASE;

DEALLOCATE PREPARE stmt;
END//

DELIMITER ;

Answer 2

Note that you do not have to use dynamic SQL. Using normal stored procedure would make your code much more readable and easier to maintain:

CREATE PROCEDURE test(
IN_STATUS VARCHAR(20),
IN_CREATED_ON DATE
) 
BEGIN

SELECT STATUS, COUNT(*) 
FROM CONTROL 
WHERE STATUS=IFNULL(IN_STATUS, STATUS) AND CREATED_ON>=IFNULL(IN_CREATED_ON,CREATED_ON)
GROUP BY STATUS;

END

Assuming your STATUS and CREATED_ON would always contain value.