public TableColumnDefinition(ColumnName columnName, ColumnDefinition columnDefinition) {
			Debug.Assert(columnName != null);
			Debug.Assert(columnDefinition != null);
			AssertIsNotWildcard(columnName);
			this.columnName = columnName;
			this.columnDefinition = columnDefinition;
		}
		public AlterTableColumnDefinitionStatement(Qualified<SchemaName, TableName> tableName, ColumnName columnName, ColumnDefinition definition): base(tableName, columnName) {
			Debug.Assert(definition != null);
			this.definition = definition;
		}