在存储过程中检索多行

Question

我需要执行完整的 table 级别扫描，因为它应该根据用户 ID 检索多行。

因为我曾经得到 sqlMessage 说明 'Subquery returns more than 1 row'。

{ Error: ER_SUBQUERY_NO_1_ROW: Subquery returns more than 1 row
  ...
  code: 'ER_SUBQUERY_NO_1_ROW',
  errno: 1242,
  sqlMessage: 'Subquery returns more than 1 row',
  sqlState: '21000',
  index: 0,
  sql: 'CALL GetLocationTag(1)' }

这是对 GetLocationTag() 代码的调用

DELIMITER $$

CREATE
    DEFINER = `root`@`localhost`
    PROCEDURE `someDB`.`GetLocationTag`(IN `UserId` BIGINT)
    LANGUAGE SQL
    DETERMINISTIC
    READS SQL DATA 
    SQL SECURITY DEFINER 
    COMMENT 'Retrieves Multiple Stored Location Tags, Address, Location, etc. based on User_ID'
    BEGIN
        DECLARE flag INT(11);
        DECLARE locRecord VARCHAR(255);

            IF EXISTS (SELECT * FROM `location_map` WHERE `user_id` = User_Id ) THEN  
                BEGIN
                    SELECT * INTO locRecord FROM `location_map` WHERE `user_id` = User_Id;
                    SET flag = 1;
                END;            
            ELSE
                SET flag = 0;
                SET locRecord = 0;
            END IF;

        SELECT locRecord, flag;
    END$$

DELIMITER ;

对于下面的查询，

SELECT * INTO locRecord FROM `location_map` WHERE `user_id` = User_Id;

我如何需要以数组的形式检索所有行并将其存储到变量中或者我应该如何编写代码以便解决错误消息?

Answer 1

使用视图来存储您获取的数据而不是变量

DELIMITER $$

CREATE
    DEFINER = `root`@`localhost`
    PROCEDURE `someDB`.`GetLocationTag`(IN `User_Id` BIGINT)
    LANGUAGE SQL
    DETERMINISTIC
    MODIFIES SQL DATA
    SQL SECURITY DEFINER
    COMMENT 'Retrieves Multiple Stored Location Tags, Address, Location, etc. based on User_ID'
    BEGIN
        DECLARE flag INT(11);
        DECLARE locRecord VARCHAR(255);

            IF EXISTS (SELECT * FROM `location_map` WHERE `user_id` = User_Id ) THEN  
                BEGIN
                    SET @viewQry = CONCAT('CREATE OR REPLACE VIEW `someDB`.`temp` as SELECT *, 1 as flag FROM `location_map` WHERE `user_id` = ',User_Id,';');
                    PREPARE stmt FROM @viewQry; 
                    EXECUTE stmt; 
                    DEALLOCATE PREPARE stmt;
                    SELECT * FROM temp;
                END;            
            ELSE
                SELECT 0 AS locRecord, 0 AS flag;
            END IF;
    END$$

DELIMITER ;

在存储过程中检索多行

Retrieving more than one rows in a stored procedure

mysql

sql

stored-procedures

subquery

mysql-error-1242