JDBC addition, deletion, modification, and query

 

Add statement:

Statement ST = conn. createstatement ();

String SQL = "insert into user (....) Values (.....) ";

IntNum = st.exe cuteupdate (SQL );

If(Num> 0 ){

System.Out. Println ("inserted successfully !!! ");

}

Delete statement:

Statement ST = conn. createstatement ();

String SQL = "delete from user where id = 1;

IntNum = st.exe cuteupdate (SQL );

If(Num> 0 ){

System.Out. Println ("deleted successfully !!! ");

}

Modify statement:

Statement ST = conn. createstatement ();

String SQL = "update user set name = ''where name = ''";

IntNum = st.exe cuteupdate (SQL );

If(Num> 0 ){

System.Out. Println ("modification successful !!! ");

}

Query statement:

Statement ST = conn. createstatement ();

String SQL = "select * from user where id = 1;

Resultset rs= St.exe cuteupdate (SQL );

While(Rs. Next ()){

// Call the RS Method Based on the Data Type of the retrieved Column

// Map to a Java object

}

Release resources

After the program is running, database-related resources will not be automatically released. We need to manually release the resultset, statement, and connection

Connection is a very valuable resource. It should be released as soon as possible after use.

To ensure that the Code for releasing resources will be executed, we usually put them in finally