com.hazelcast.org.apache.calcite.sql.JoinType Maven / Gradle / Ivy
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to you under the Apache License, Version 2.0
* (the "License"); you may not use this file except in com.hazelcast.com.liance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.com.hazelcast.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.hazelcast.org.apache.calcite.sql;
import com.hazelcast.org.apache.calcite.sql.parser.SqlParserPos;
import java.util.Locale;
/**
* Enumerates the types of join.
*/
public enum JoinType {
/**
* Inner join.
*/
INNER,
/**
* Full outer join.
*/
FULL,
/**
* Cross join (also known as Cartesian product).
*/
CROSS,
/**
* Left outer join.
*/
LEFT,
/**
* Right outer join.
*/
RIGHT,
/**
* Left semi join.
*
* Not used by Calcite; only in Babel's Hive dialect.
*/
LEFT_SEMI_JOIN,
/**
* Comma join: the good old-fashioned SQL FROM clause,
* where table expressions are specified with com.hazelcast.com.as between them, and
* join conditions are specified in the WHERE clause.
*/
COMMA;
/** Lower-case name. */
public final String lowerName = name().toLowerCase(Locale.ROOT);
/**
* Returns whether a join of this type may generate NULL values on the
* left-hand side.
*/
public boolean generatesNullsOnLeft() {
return this == RIGHT || this == FULL;
}
/**
* Returns whether a join of this type may generate NULL values on the
* right-hand side.
*/
public boolean generatesNullsOnRight() {
return this == LEFT || this == FULL;
}
/**
* Creates a parse-tree node representing an occurrence of this
* condition type keyword at a particular position in the parsed
* text.
*/
public SqlLiteral symbol(SqlParserPos pos) {
return SqlLiteral.createSymbol(this, pos);
}
}