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Transaction one. What is a transaction?

is to execute a set of SQL instructions, which either executes successfully or all fails if one fails

Two. Operation of the transaction

　Note: The connection method is related to transactional operations

The same transaction requires the same connection implementation class object

Process:

To open a transaction:

Con.setautocommit (false);//Turn off autocommit

True to turn on auto-commit

Commit a transaction

Con.commit ();

Rolling back a transaction

Con.rollback ();

Analysis of small transfer cases:

2     Try3{//Turn on transaction: The system will then treat all of the following SQL execution as a whole4         inti = update:-1005         intj = update:+1006         if(i > 0 && J > 0){7            //COMMIT TRANSACTION: When all SQL instructions are executed successfully, all operations on the database, commit transactions, will be permanent and cannot be changed8System.out.println ("Successful transfer!"));9         }Ten}Catch(Exception e) One     { A          //Rollback Transaction: When there is a problem in your transaction and not all execution succeeds, review the transaction so that all previous operations on the database are revoked -}

Code Demo:

1  Public classDemo {2      Public Static voidMain (string[] args) {3Connection con=NULL;4         Try{5Queryrunner QR =NewQueryrunner ();6con=c3p0utils.getconnection ();7             //Open Transaction8Con.setautocommit (false);9             intRe1 = qr.update ("Update account set money=money-?") Where id=? ", 300,342);Ten             intRe2 = qr.update ("Update account set money=money+?") Where id=? ", 300,345); One             if(re1>0&&re2>0){ A                 //both execute a successful commit transaction - con.commit (); -}Else{ the                 //failure to perform a manual rollback of a transaction - Con.rollback (); -             } -}Catch(Exception e) { +             //exception rollback TRANSACTION occurred -             Try { + Con.rollback (); A}Catch(SQLException E1) { at                 //TODO auto-generated Catch block - e1.printstacktrace (); -             } -}finally { -             Try { -                 //put the connection back into the connection pool in con.close (); -}Catch(SQLException e) { to                 //TODO auto-generated Catch block + e.printstacktrace (); -             } the         } *     } $}

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