/*
 * Copyright 2016-2018 shardingsphere.io.
 * <p>
 * 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.
 * </p>
 */

package io.shardingsphere.core.parsing.parser.context.selectitem;

import com.google.common.base.Optional;
import com.google.common.base.Strings;
import io.shardingsphere.core.parsing.lexer.token.DefaultKeyword;
import io.shardingsphere.core.util.SQLUtil;
import lombok.EqualsAndHashCode;
import lombok.Getter;
import lombok.RequiredArgsConstructor;
import lombok.ToString;

/**
 * Aggregation distinct select item.
 *
 * @author panjuan
 */
@Getter
@EqualsAndHashCode
@ToString
@RequiredArgsConstructor
public final class AggregationDistinctSelectItem implements DistinctSelectItem {
    
    private final String distinctColumn;
    
    @Override
    public String getExpression() {
        return Strings.isNullOrEmpty(distinctColumn) ? DefaultKeyword.DISTINCT.name() : SQLUtil.getExactlyValue(DefaultKeyword.DISTINCT + " " + distinctColumn);
    }
    
    /**
     * Get column label.
     *
     * @return column label
     */
    public String getColumnLabel() {
        return alias.isPresent() ? alias.get() : getExpression();
    }
}

@@ -691,188 +691,55 @@
 ort 
-com.google.common.base.Optional;%0Aimport com.google.common.base.Strings;%0Aimport io.shardingsphere.core.parsing.lexer.token.DefaultKeyword;%0Aimport io.shardingsphere.core.util.SQLUtil
+io.shardingsphere.core.constant.AggregationType
 ;%0Aim
@@ -963,33 +963,8 @@
 ing%0A
-@RequiredArgsConstructor%0A
 publ
@@ -1012,17 +1012,14 @@
 tem 
-implement
+extend
 s Di
@@ -1064,441 +1064,28 @@
 nal 
-String distinctColumn;%0A    %0A    @Override%0A    public String getExpression() %7B%0A        return Strings.isNullOrEmpty(distinctColumn) ? DefaultKeyword.DISTINCT.name() : SQLUtil.getExactlyValue(DefaultKeyword.DISTINCT + %22 %22 + distinctColumn);%0A    %7D%0A    %0A    /**%0A     * Get column label.%0A     *%0A     * @return column label%0A     */%0A    public String getColumnLabel() %7B%0A        return alias.isPresent() ? alias.get() : getExpression();%0A    %7D
+AggregationType type;
 %0A%7D%0A

modify AggregationDistinctSelectItem