Question

我正在使用动态查询在MySQL中编写存储过程，如下所示：

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 ;

我打算使用下面显示的签名重写此过程。这将在比较日期时提供正确的逻辑。

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

主要问题是;如何将谓词与日期连接到@query？

Answer 1

尝试使用CASE并传递参数：

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

请注意，您不必使用动态SQL。使用普通的存储过程可以使您的代码更易读，更易于维护：

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

假设您的STATUS和CREATED_ON始终包含值。

使用MySQL中的Date参数在存储过程中进行动态查询

2 个答案: