Check-a small surprise today

FirstNon-primary keyThe field (for example, UID) is set to unique (indicating that this field cannot have duplicate values), and then the field is checked and re-captured in daoimpl. If an exception is caught, the UID field that is performing the insert () or update () operation is the same as the existing uid.

Connect to the database using JDBC: In the insert () method

1. Try {
3. } Catch (mysqlintegrityconstraintviolationexception mcve ){
4. System. Err. println ("duplicate data is not allowed !!! "); // Prompt here
5. } Catch (sqlexception sqle ){
7. } Catch (exception e ){
9. } Finally {
11. }

Connect to the database using hibernate: In the insert () method

1. Try {
3. } Catch (constraintviolationexception CVE ){
4. System. Err. println ("duplicate data is not allowed"); // a prompt is displayed here.
5. }