如何在存储过程中编写 MySQL 处理程序，抛出错误消息并继续执行?
mysqlmysqli database
众所周知，每当 MySQL 存储过程中发生异常时，通过抛出适当的错误消息来处理它非常重要，因为如果我们不处理异常，则存储过程中的应用程序可能会因该特定异常而失败。MySQL 提供了一个处理程序，它会抛出错误消息并继续执行。为了演示这一点，我们使用以下示例，其中我们试图在主键列中插入重复值。
示例
mysql> DELIMITER // mysql> Create Procedure Insert_Studentdetails(S_Studentid INT, S_StudentName Varchar(20), S_Address Varchar(20)) -> BEGIN -> DECLARE CONTINUE HANDLER FOR SQLEXCEPTION SELECT 'Got an error'; -> INSERT INTO Student_detail -> (Studentid, StudentName, Address) -> Values(S_Studentid,S_StudentName,S_Address); -> Select * from Student_detail; -> END // Query OK, 0 rows affected (0.19 sec)
调用上述过程，如果我们尝试在列"studentid"中输入重复的值，它将抛出错误消息"got an error"并继续执行。
mysql> Delimiter ; mysql> CALL Insert_Studentdetails(100, 'Gaurav', 'Delhi'); +-----------+-------------+---------+ | Studentid | StudentName | address | +-----------+-------------+---------+ | 100 | Gaurav | Delhi | +-----------+-------------+---------+ 1 row in set (0.11 sec) Query OK, 0 rows affected (0.12 sec) mysql> CALL Insert_Studentdetails(101, 'Raman', 'Shimla'); +-----------+-------------+---------+ | Studentid | StudentName | address | +-----------+-------------+---------+ | 100 | Gaurav | Delhi | | 101 | Raman | Shimla | +-----------+-------------+---------+ 2 rows in set (0.06 sec) Query OK, 0 rows affected (0.12 sec) mysql> CALL Insert_Studentdetails(101, 'Rahul', 'Jaipur'); +--------------+ | Got an error | +--------------+ | Got an error | +--------------+ 1 row in set (0.03 sec) +-----------+-------------+---------+ | Studentid | StudentName | address | +-----------+-------------+---------+ | 100 | Gaurav | Delhi | | 101 | Raman | Shimla | +-----------+-------------+---------+ 2 rows in set (0.04 sec) Query OK, 0 rows affected (0.05 sec) mysql> CALL Insert_Studentdetails(103, 'Rahul', 'Jaipur'); +-----------+-------------+---------+ | Studentid | StudentName | address | +-----------+-------------+---------+ | 100 | Gaurav | Delhi | | 101 | Raman | Shimla | | 103 | Rahul | Jaipur | +-----------+-------------+---------+ 3 rows in set (0.08 sec) Query OK, 0 rows affected (0.10 sec)
