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();
}
}
}
