Checking if user exists in Oracle Database - java jdbc

Question

So I have this working code/prepared statement that adds a username and password into a database, however I need to check if the username already exists in the code.

public void addUser(Connection conn, PreparedStatement pstmnt, String username, String password) 
    {
        try 
        {
            pstmnt = conn.prepareStatement("insert into users values (?,?,?)");
            pstmnt.setInt(1, 0);
            pstmnt.setString(2, username);
            pstmnt.setString(3, password);
            pstmnt.executeUpdate();
        } 
        catch (SQLException e) { System.out.println("Error: " + e.getMessage()); }

        System.out.println(username + " has been added");
    }

Is there any simple way to do this?

What @UwePlonus says -- just enforce the constraint at the database level. This is what a primary key is. — fge
– fge, Commented Jun 18, 2013 at 13:29

sidshu · Accepted Answer · 2013-06-18 13:14:43Z

1

You can add a unique constraint in the DB and handle the exception in addUSer accordingly

answered Jun 18, 2013 at 13:14

sidshu

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1 Comment

wolφi Over a year ago

+1, that is the best solution. For example with the statement ALTER TABLE users ADD CONSTRAINT users_uq_name UNIQUE (username);

LoganMzz · Accepted Answer · 2013-06-18 13:14:18Z

0

If there's no many duplicate key risk, you can just try and check the error code if it matches "dup key error" (Error ORA-00001).

Else you must lock the entire table, check for key existence, update and then commit (which release the lock)

answered Jun 18, 2013 at 13:14

LoganMzz

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