internal void CheckState() { DataTable table = this.columns[0].Table; if (table == null) { throw ExceptionBuilder.ColumnNotInAnyTable(); } for (int i = 1; i < this.columns.Length; i++) { if (this.columns[i].Table == null) { throw ExceptionBuilder.ColumnNotInAnyTable(); } if (this.columns[i].Table != table) { throw ExceptionBuilder.KeyTableMismatch(); } } }