com.google.zetasql.Column Maven / Gradle / Ivy
/*
* Copyright 2019 Google LLC
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*/
package com.google.zetasql;
/**
* A column in Table.
*/
public interface Column {
/**
* The column name. Columns must have non-empty names. Anonymous columns
* are not supported.
*/
public String getName();
/**
* The fully-qualified name, including the table name.
*/
public String getFullName();
public Type getType();
/**
* Pseudo-columns can be selected explicitly but do not show up in SELECT *. This can be used for
* any hidden or virtual column or lazily computed value in a table.
*
* Pseudo-columns can be used on value tables to provide additional named values outside the
* content of the row value.
*
*
Pseudo-columns are normally not writable in INSERTs or UPDATEs, but this is up to the engine
* and not checked by ZetaSQL.
*
*
Pseudo-columns are specified in more detail in the value tables spec:
* (broken link)
*/
public boolean isPseudoColumn();
/** Returns true if the column is writable. */
public boolean isWritableColumn();
/**
* Returns true if the column can be SET to DEFAULT in an UPDATE DML statement. Setting a
* non-writable column to DEFAULT denotes that the generated column value must be re-evaluated.
* This is currently only allowed for STORED VOLATILE generated columns, where
* isWritableColumn()==false and canUpdateToDefault() is engine specific. See:
* (broken link).
*/
public boolean canUpdateToDefault();
}