MySQL obtains the value of the auto_increment field just inserted.

MySQL obtains the value of the auto_increment field just inserted.

Select max (ID) from testnotnull cannot be used;

In this way, you can obtain the value of the incremental field you just inserted,

Multithreading is not considered.

 

A better method is:

Use Java. SQL. preparedstatement pstmt = conn. preparestatement (SQL, statement. return_generated_keys );

After inserting data, that is, after executing pstmt.exe cuteupdate,

Resultset rs = pstmt. getgeneratedkeys (); obtain the value of the newly inserted auto-increment field.

Test code:

 

@ Test <br/> Public void testnextvalue () {<br/> try {<br/> string MySQL = "JDBC: mysql: // localhost/hibernate "; <br/> class. forname ("com. mySQL. JDBC. driver "); <br/> JAVA. SQL. connection conn = drivermanager. getconnection (MySQL, "root", "root"); <br/> string SQL = "insert into testnotnull values (null ,?, ?) "; <Br/> JAVA. SQL. preparedstatement pstmt = Conn. preparestatement (SQL, statement. return_generated_keys); <br/> Conn. setautocommit (false); <br/> int I = 1; <br/> pstmt. setint (I ++, 234); <br/> pstmt. setstring (I ++, "sdfsdf"); <br/> pstmt.exe cuteupdate (); <br/> resultset rs = pstmt. getgeneratedkeys (); <br/> system. out. println ("the value is"); <br/> If (RS. next () {<br/> system. out. println (RS. getint (1); <br/>}< br/> Conn. commit (); <br/> Conn. setautocommit (true); <br/>} catch (exception e) {<br/> E. printstacktrace (); <br/>}finally {<br/> // do close .... <br/>}< br/>}

If you only want to obtain the maximum value of auto_increment

Select max (ID) from testnotnull;

Or show table status from Hibernate like 'testnotnull '; To Get The auto_increment value.

Neither of these methods is thread-Safe !!!!!