mysql 并列游标

-- 检查权限
SHOW GRANTS FOR 'username'@'host';

-- 检查查询语句
SELECT * FROM table_name WHERE condition;

-- 检查数据库连接
SHOW PROCESSLIST;

-- 限制游标数量
SET GLOBAL max_sp_recursion_depth = 10;

-- 分批次处理数据
DECLARE cur CURSOR FOR SELECT * FROM table_name WHERE condition;
DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = TRUE;
OPEN cur;
read_loop: LOOP
    FETCH cur INTO var1, var2, ..., varN;
    IF done THEN
        LEAVE read_loop;
    END IF;
    -- 处理数据
END LOOP;
CLOSE cur;

-- 使用事务
START TRANSACTION;
DECLARE cur CURSOR FOR SELECT * FROM table_name WHERE condition FOR UPDATE;
OPEN cur;
read_loop: LOOP
    FETCH cur INTO var1, var2, ..., varN;
    IF done THEN
        LEAVE read_loop;
    END IF;
    -- 处理数据
END LOOP;
CLOSE cur;
COMMIT;