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.FlexConsts;
019import com.mybatisflex.core.dialect.IDialect;
020import com.mybatisflex.core.util.SqlUtil;
021import com.mybatisflex.core.util.StringUtil;
022
023import java.util.List;
024
025/**
026 * 数据库 聚合函数，例如 count(id) ，max(account.age) 等等
027 */
028public class FunctionQueryColumn extends QueryColumn implements HasParamsColumn {
029
030    protected String fnName;
031    protected QueryColumn column;
032
033    public FunctionQueryColumn(String fnName, String column) {
034        SqlUtil.keepColumnSafely(fnName);
035        SqlUtil.keepColumnSafely(column);
036        this.fnName = fnName;
037        this.column = new QueryColumn(column);
038    }
039
040    public FunctionQueryColumn(String fnName, QueryColumn column) {
041        SqlUtil.keepColumnSafely(fnName);
042        this.fnName = fnName;
043        this.column = column;
044    }
045
046    public String getFnName() {
047        return fnName;
048    }
049
050    public void setFnName(String fnName) {
051        this.fnName = fnName;
052    }
053
054    public QueryColumn getColumn() {
055        return column;
056    }
057
058    public void setColumn(QueryColumn column) {
059        this.column = column;
060    }
061
062    @Override
063    public Object[] getParamValues() {
064        if (column instanceof HasParamsColumn) {
065            return ((HasParamsColumn) column).getParamValues();
066        }
067        return FlexConsts.EMPTY_ARRAY;
068    }
069
070    @Override
071    public String toSelectSql(List<QueryTable> queryTables, IDialect dialect) {
072        String sql = column.toSelectSql(queryTables, dialect);
073        return StringUtil.isBlank(sql) ? "" : fnName + "(" + sql + ")" + WrapperUtil.buildAsAlias(alias, dialect);
074    }
075
076    @Override
077    public QueryColumn as(String alias) {
078        SqlUtil.keepColumnSafely(alias);
079        this.alias = alias;
080        return this;
081    }
082
083    @Override
084    public String toString() {
085        return "FunctionQueryColumn{" +
086                "fnName='" + fnName + '\'' +
087                ", column=" + column +
088                '}';
089    }
090
091
092}