如何在存储过程中的 Mysql 中创建游标

Question

我创建了一个存储过程，我需要从投诉表中获取所有记录，然后遍历它并找出谁在特定投诉时发表了评论。您可以将其假设为博客应用程序，其中一个博客可以有多个评论。 我收到语法错误

Declare cur CURSOR statement,

这可能是什么问题或我错过了什么。

这是我收到的以下消息

错误代码：1064 您的 SQL 语法有错误；检查与您的 MySQL 服务器版本相对应的手册，以获取正确的语法，以便在第 22 行的 'declare cur CURSOR for SELECT id,user_id FROM 投诉3 WHERE user_id IN(SELEC' 附近使用)

下面是我的过程

DELIMITER $$

CREATE PROCEDURE `myDB`.`ShowResult`(user_id INT, hours INT,L_Complaint_id INT)
BEGIN
 DECLARE complaint_count INT;
 DECLARE 24Hrs_count INT;
 DECLARE 48Hrs_count INT;
 DECLARE Gr_48Hrs_count INT;
 DECLARE notCommented INT;
 DECLARE agentName VARCHAR(100);
 DECLARE v_agentId INT;
 DECLARE v_userId INT;
 DECLARE lastUserCommentDate DATETIME;
 DECLARE lastInternalUserCommentDate DATETIME;
 DECLARE tempDate INT;
 DECLARE v_complaint_id INT;

 SET 24Hrs_count =0;
 SET 48Hrs_count =0;
 SET Gr_48Hrs_count =0;
 SET notCommented =0;
 SET v_complaint_id =0;

 DECLARE cur CURSOR FOR SELECT id,user_id FROM complaint3 WHERE user_id IN( SELECT id FROM user3 WHERE user_type=0);   


CREATE TEMPORARY TABLE IF NOT EXISTS resultTable (
id MEDIUMINT NOT NULL AUTO_INCREMENT,t_agentId INT,t_agentName  VARCHAR(1000),t_24HrsCount INT,t_48HrsCount INT,t_Gr48HrsCount INT,
t_nullCount INT,PRIMARY KEY (id)) ENGINE = MEMORY;

SELECT COUNT(DISTINCT(id)) INTO complaint_count FROM complaint3 WHERE user_id IN(SELECT id FROM user3 WHERE user_type=0);
OPEN cur;
insert_loop: LOOP

 IF complaint_count > 0 THEN    
   FETCH cur INTO complaint_id,user_id;

      SELECT created_at INTO lastUserCommentDate FROM complaint3_diary WHERE complaint_id=v_complaint_id AND user_id = v_user_id ORDER BY id DESC LIMIT 1;
      SELECT assigned_to INTO v_agentId FROM assignment3 WHERE complaint_id=v_complaint_id AND a.expire_at IS NULL;
      SELECT NAME INTO agentName FROM user3 WHERE id=v_agentId;
      SELECT created_at INTO lastInternalUserCommentDate FROM complaint3_diary WHERE complaint_id=v_complaint_id AND user_id = v_agentId ORDER BY id DESC LIMIT 1;
  SELECT TIMESTAMPDIFF(HOUR, lastInternalUserCommentDate, lastUserCommentDate)  INTO tempDate;

  IF (tempDate >0 && tempDate <= 24) THEN
    SET 24Hrs_count =1;
  ELSEIF (tempDate >24 && tempDate <= 48) THEN
     SET 48Hrs_count = 1;
  ELSEIF (tempDate >48) THEN
     SET Gr_48Hrs_count = 1;
  ELSE
     SET notCommneted = 1;
   END IF;
      INSERT INTO resultTable(t_agentId,t_agentName,t_24HrsCount,t_48HrsCount,t_Gr48HrsCount,t_nullCount) VALUES(v_agentId,agentName,24Hrs_count,48Hrs_count,Gr_48Hrs_count,notCommneted);

ELSE
LEAVE insert_loop;
END IF;
 SET complaint_count = complaint_count - 1;
END LOOP;
CLOSE cur;
    SELECT t_agentId,t_agentName,COUNT(t_24HrsCount),COUNT(t_48HrsCount),COUNT(t_Gr48HrsCount),COUNT(t_nullCount) FROM resultTable GROUP BY agentId;

END$$

分隔符;

Answer 1

根据documentation on DECLARE

DECLARE 只允许在 BEGIN ... END 复合语句中使用，并且必须位于其开头，在任何其他语句之前。

在你的代码中，声明

DECLARE cur CURSOR FOR 
    SELECT id, user_id 
      FROM complaint3 
     WHERE user_id IN( SELECT id FROM user3 WHERE user_type = 0 );   

没有遵循申报顺序规则。因此是错误。

修改部分代码如下：

BEGIN
 DECLARE complaint_count INT;
 DECLARE 24Hrs_count INT;
 DECLARE 48Hrs_count INT;
 DECLARE Gr_48Hrs_count INT;
 DECLARE notCommented INT;
 DECLARE agentName VARCHAR(100);
 DECLARE v_agentId INT;
 DECLARE v_userId INT;
 DECLARE lastUserCommentDate DATETIME;
 DECLARE lastInternalUserCommentDate DATETIME;
 DECLARE tempDate INT;
 DECLARE v_complaint_id INT;

 DECLARE cur CURSOR FOR 
     SELECT id, user_id 
       FROM complaint3 
      WHERE user_id IN( SELECT id FROM user3 WHERE user_type = 0 );   

 SET 24Hrs_count =0;
 SET 48Hrs_count =0;
 SET Gr_48Hrs_count =0;
 SET notCommented =0;
 SET v_complaint_id =0;