Question

I get this error, Can anyone help me in finding my mistake in the query?

public boolean populateLeagues(String leaguename, String password){

        Connect connect = new Connect();
        Connection conn = connect.Connection();
        Statement stmt = conn.createStatement();            
        String query = "INSERT INTO users VALUES('" + leaguename + "')";
        stmt.executeUpdate(query);
        conn.close();
}

Answer 1

AS @Jon Skeet says, use a prepared statement and inject parameters into. In this way you don’t have to figure out all hassles about sql injection and data format(think about using a query like the one you provide to store datetime globally).
Probably leaguename value is null. Remember that default value for string type isn’t the empty strin but null