How to ensure INSERT INTO wont add the same value on the mySQL DB

Question

Is there a way to make an INSERT INTO prepared statement but make sure the name the user will give wont be put on the DB if it already exists?

public ServerConn(String sql_name,int sql_year,String sql_ticket)
  {
   try
        {
           Class.forName( "com.mysql.jdbc.Driver" ) ;
           java.sql.Connection conn = DriverManager.getConnection("jdbc:mysql://localhost/promitheas?user=gunner&password=1234") ;
           this.sql_name = sql_name;
           this.sql_year = sql_year;
           this.sql_ticket = sql_ticket;
           PreparedStatement ps = conn.prepareStatement("INSERT INTO tickets (xronia,ticket,name) VALUES (?,?,?)");
           ps.setInt(1,sql_year);
           ps.setString(2,sql_ticket);
           ps.setString(3,sql_name);
           ps.executeUpdate();
           System.out.println("Done!");
   } catch (SQLException case1){
         case1.printStackTrace();
   } catch(Exception case2){
         case2.printStackTrace();
 }
}

Answer 1

You can check this on the database by adding a unique constraint like this :

ALTER TABLE tickets ADD UNIQUE (name)

The INSERT won't be possible if the name already exists in the database.

Answer 2

Make the row unique in the database? If you try to insert identical data you should get a message telling you that the data already present and can not be stored because only unique data can be inserted.

Answer 3

This can be done by in different ways. You could create a unique constraint or you could just write another query to check whether the data already exists in the database:

ResultSet rs = query ("SELECT * FROM table_name WHERE conditions" + ";");
if (rs.next() )
//it exists in the table already

Answer 4

Two choices for resolving it :

• alter the table and add unique constraint on this column

• add some codes before the opertion insert. And the goal of the new codes is to validate the name dosen't exist in the actual table.