Not able to handle MysqlIntegrity exception in sqlexception

Question

I am trying to catch MysqlIntegrityException in catch clause of SQL exception but it does not seems to handle it in catch block of SQL exception. What might be the reason and how to solve it.

catch(SQLException e)
{
//not reaching here
}

http://stackoverflow.com/questions/15894455/java-mysql-integrity-constraint-violation-exception — ngrashia, Jul 17 '14 at 06:50
http://stackoverflow.com/questions/2201119/java-mysql-integrity-violation-handling — ngrashia, Jul 17 '14 at 06:50
but i am not able to understand MysqlIntegrity exception is a subclass of sqlexception , still not able to handle — user3841558, Jul 17 '14 at 07:03
If you want any answers other than the speculative one I posted below, please share the code that throws the exception. Your conclusion that your issue is a problem with the `catch` block above is almost certainly mistaken. — Luke Woodward, Jul 19 '14 at 12:10

score 0 · Answer 1 · answered Jul 19 '14 at 12:06

Sorry, cannot reproduce this one.

Here's some tables I created in the MySQL monitor:

mysql> create table a (id int not null primary key auto_increment);
Query OK, 0 rows affected (0.09 sec)

mysql> create table b (b_id int not null primary key auto_increment, a_id int not null);
Query OK, 0 rows affected (0.06 sec)

mysql> alter table b add constraint a_fk foreign key (a_id) references a(id);
Query OK, 0 rows affected (0.19 sec)
Records: 0  Duplicates: 0  Warnings: 0

mysql> insert into a() values();
Query OK, 1 row affected (0.04 sec)

mysql> insert into a() values();
Query OK, 1 row affected (0.03 sec)

mysql> insert into b (a_id) values (1);
Query OK, 1 row affected (0.04 sec)

Let's just test that the foreign key constraint is working:

mysql> delete from a where id = 1;
ERROR 1451 (23000): Cannot delete or update a parent row: a foreign key constraint fails (`test`.`b`, CONSTRAINT `a_fk` FOREIGN KEY (`a_id`) REFERENCES `a` (`id`))

I then wrote this Java class:

import java.sql.*;

public class MySQLExceptionTest {
    public static void main(String[] args) throws Exception {
        DriverManager.registerDriver(new com.mysql.jdbc.Driver());
        Connection c = DriverManager.getConnection("jdbc:mysql://localhost:3306/test", "user", "password");
        PreparedStatement stmt = c.prepareStatement("DELETE FROM a WHERE id = 1");
        try {
            stmt.execute();
        }
        catch (SQLException e) {
            System.out.println("Got a " + e.getClass().getName() + " with message " + e.getMessage());
        }
    }
}

When I ran this class, I got the following output:

Got a com.mysql.jdbc.exceptions.jdbc4.MySQLIntegrityConstraintViolationException with message Cannot delete or update a parent row: a foreign key constraint fails (`test`.`b`, CONSTRAINT `a_fk` FOREIGN KEY (`a_id`) REFERENCES `a` (`id`))

My code can catch this exception, so why can't yours? Well, with the almost total absence of any of your code, I can only offer a couple of speculative answers:

the exception is caught somewhere inside the try block and perhaps wrapped and rethrown,
the code in the try block starts a new Thread, and the exception is thrown in the new thread.

Not able to handle MysqlIntegrity exception in sqlexception

1 Answers1