Question

您好我一直尝试通过CallableStatement调用过程来选择多行。当我尝试将结果集填充到组合框时，代码将返回错误，如下所示。

Java错误：

                   java.sql.SQLException: Subquery returns more than 1 row

存储过程：

CREATE DEFINER=`user_name`@`%` PROCEDURE `GET_USER_PROFILE`(
            IN p_user_id VARCHAR(150),
            IN p_role VARCHAR(150),
            OUT p_user_data VARCHAR(200),
            OUT p_city VARCHAR(150),
            OUT p_state VARCHAR(150),
            OUT p_country VARCHAR(150),
            OUT q_Msg VARCHAR(150))
BEGIN

DECLARE available INT DEFAULT 0;
 SET p_city = (SELECT CITY FROM countries GROUP BY CITY);
 SET p_state = (SELECT STATE FROM countries GROUP BY STATE);
 SET p_country = (SELECT COUNTRY FROM countries GROUP BY COUNTRY);

SELECT COUNT(EMAIL) INTO available FROM STAFF_PROFILE WHERE EMAIL = p_user_id AND ROLE = p_role;

IF(available=1) THEN
        SET p_user_data = (SELECT * FROM STAFF_PROFILE WHERE EMAIL = p_user_id AND ROLE = p_role );
else
    SET q_Msg = 'USER_LOGGED_FIRST';
END IF;

END

Answer 1

@DaveHowes和@Ilya是正确的，问题在于您的SQL语句。

让我们在您的国家/地区表中包含以下内容：

city            state           country
'New York'      'New York'      'USA'
'Los Angeles'   'California'    'USA'
'Chicago'       'Illinois'      'USA'
'Ottawa'        ''              'Canada'

现在，如果我们从您的示例中获取子查询：

SELECT city FROM countries GROUP BY city

将返回：

city
'New York'
'Los Angeles'
'Chicago'
'Ottawa'

您正在尝试将多个结果分配给varchar，因此您将获得异常“子查询返回多于一行”。

错误：子查询返回多行

1 个答案: