org.apache.openjpa.jdbc.kernel.exps.Count Maven / Gradle / Ivy
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* 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 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 org.apache.openjpa.jdbc.kernel.exps;
import org.apache.openjpa.jdbc.schema.Column;
import org.apache.openjpa.jdbc.sql.SQLBuffer;
import org.apache.openjpa.jdbc.sql.Select;
/**
* Count non-null values.
*
* @author Abe White
*/
class Count
extends UnaryOp {
private boolean isCountMultiColumns = false;
private boolean isCountDistinct = false;
/**
* Constructor. Provide the value to operate on.
*/
public Count(Val val) {
super(val);
if (val instanceof Distinct)
isCountDistinct = true;
}
public ExpState initialize(Select sel, ExpContext ctx, int flags) {
// join into related object if present
ExpState expState = initializeValue(sel, ctx, JOIN_REL);
Val val = isCountDistinct ? ((Distinct)getValue()).getValue() : getValue();
if (val instanceof PCPath) {
Column[] cols = ((PCPath)val).getColumns(expState);
if (cols.length > 1) {
isCountMultiColumns = true;
}
}
return expState;
}
protected Class getType(Class c) {
return long.class;
}
protected String getOperator() {
return "COUNT";
}
public boolean isAggregate() {
return true;
}
public boolean isCountDistinctMultiCols() {
return isCountDistinct && isCountMultiColumns;
}
/**
* Overrides SQL formation by replacing COUNT(column) by COUNT(*) when specific conditions are met and
* DBDictionary configuration useWildCardForCount is set.
*/
@Override
public void appendTo(Select sel, ExpContext ctx, ExpState state, SQLBuffer sql, int index) {
if (isCountDistinctMultiCols()) {
getValue().appendTo(sel, ctx, state, sql, 0);
sql.addCastForParam(getOperator(), getValue());
} else
super.appendTo(sel, ctx, state, sql, index);
if ((ctx.store.getDBDictionary().useWildCardForCount && state.joins.isEmpty()) ||
!isCountDistinct && isCountMultiColumns){
String s = sql.getSQL();
if (s.startsWith("COUNT(") && s.endsWith(")")) {
sql.replaceSqlString("COUNT(".length(), s.length()-1, "*");
}
}
}
}