001/**
002 * Copyright (c) 2022-2023, Mybatis-Flex (fuhai999@gmail.com).
003 * <p>
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 * <p>
008 * http://www.apache.org/licenses/LICENSE-2.0
009 * <p>
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016package com.mybatisflex.core.query;
017
018import com.mybatisflex.core.dialect.IDialect;
019import com.mybatisflex.core.util.SqlUtil;
020import com.mybatisflex.core.util.StringUtil;
021
022import java.util.List;
023
024/**
025 * 数据库 聚合函数，例如 count(id) ，max(account.age) 等等
026 */
027public class FunctionQueryColumn extends QueryColumn {
028
029    protected String fnName;
030    protected QueryColumn column;
031
032    public FunctionQueryColumn(String fnName, String column) {
033        SqlUtil.keepColumnSafely(fnName);
034        SqlUtil.keepColumnSafely(column);
035        this.fnName = fnName;
036        this.column = new QueryColumn(column);
037    }
038
039    public FunctionQueryColumn(String fnName, QueryColumn column) {
040        SqlUtil.keepColumnSafely(fnName);
041        this.fnName = fnName;
042        this.column = column;
043    }
044
045    public String getFnName() {
046        return fnName;
047    }
048
049    public void setFnName(String fnName) {
050        this.fnName = fnName;
051    }
052
053    public QueryColumn getColumn() {
054        return column;
055    }
056
057    public void setColumn(QueryColumn column) {
058        this.column = column;
059    }
060
061    @Override
062    public String toSelectSql(List<QueryTable> queryTables, IDialect dialect) {
063        String sql = column.toSelectSql(queryTables, dialect);
064        return StringUtil.isBlank(sql) ? "" : fnName + "(" + sql + ")" + WrapperUtil.buildAsAlias(alias);
065    }
066
067    @Override
068    public QueryColumn as(String alias) {
069        SqlUtil.keepColumnSafely(alias);
070        this.alias = alias;
071        return this;
072    }
073
074    @Override
075    public String toString() {
076        return "FunctionQueryColumn{" +
077                "fnName='" + fnName + '\'' +
078                ", column=" + column +
079                '}';
080    }
081}