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MyBatis framework for generating dynamic SQL
/**
* Copyright 2016-2018 the original author or authors.
*
* 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 org.mybatis.dynamic.sql.select.aggregate;
import java.util.Optional;
import org.mybatis.dynamic.sql.BasicColumn;
import org.mybatis.dynamic.sql.render.TableAliasCalculator;
/**
* CountAll seems like the other aggregates, but it is special because there is no column.
* Rather than dealing with a useless and confusing abstraction, we simply implement
* BasicColumn directly.
*
* @author Jeff Butler
*/
public class CountAll implements BasicColumn {
private String alias;
public CountAll() {
super();
}
@Override
public String renderWithTableAlias(TableAliasCalculator tableAliasCalculator) {
return "count(*)"; //$NON-NLS-1$
}
@Override
public Optional alias() {
return Optional.ofNullable(alias);
}
@Override
public CountAll as(String alias) {
CountAll copy = new CountAll();
copy.alias = alias;
return copy;
}
}