如何在 MYSQL 中实现回滚事务和错误消息

Question

I Have sample procedure.

CREATE PROCEDURE `sample_procedure ` 
(
IN IDIn bigint(20),
IN MainIDIn bigint(20),
IN NameIn  varchar(20)
)
 READS SQL DATA
    DETERMINISTIC
BEGIN
INSERT INTO tbl_DEPT
(
ID,
Name)
Select 1,'Mohan';

IF NOT EXISTS (SELECT ID FROM tbl_emp  te  WHERE te.ID = IDIn) THEN 
INSERT INTO tbl_emp
(
MainID,
Name) 
VALUES (MainIDIn,
        NameIn);
ELSE 
IF  EXISTS (SELECT ID FROM tbl_emp  te  WHERE te.ID = IDIn) THEN 
  UPDATE tbl_emp  
  set
    MainID =MainIDIn,
    name = NameIn
  WHERE te.ID= IDIn;
  END IF;
  END IF;
END

Call sample_procedure(1,2,Sampl123)

I'm just sending some irrelevant Data into the Procedure so that procedure gets failed. But how we need to implement roll back means it should come to the starting state with out Inserting Records into the tbl_DEPT also.

IN T-SQL we will have

BEGIN
    SET NOCOUNT ON
    BEGIN TRANSACTION
    BEGIN TRY
        SET @OUT = "success";
        COMMIT TRANSACTION
    END TRY

    BEGIN CATCH
        set @out = 'not success';
        ROLLBACK TRANSACTION
    END CATCH
END

this kind of TRY CATCH blocks and to capture Error

 "ERROR_NUMBER() AS ErrorNumber,
    ERROR_SEVERITY() AS ErrorSeverity"

In the same way in MYSQL I'm looking for TRY CATCH and ROLL BACK Mechanism.

IF Procedure fails it should ROLL BACK and Not to load in any of the table.

Can any one Suggest me in MYSQL.

Answer 1

Mysql does not use try/catch. If uses handlers, eg the EXIT handler that will terminate the execution of the SP:

DECLARE EXIT HANDLER FOR SQLEXCEPTION 
BEGIN 
    ROLLBACK;
    -- other logic
END;

There are other type of handlers as well.