MyBatis databaseId实现多种数据类型实现

最近的项目，最开始是使用MySQL进行开发，最终部署到多地区服务器。然而前几天说，有个地区的数据库使用的是Oracle。于是我要寻找一种方案，能让MySQL语法和Oracle语法同时存在。最终发现了MyBatis的这个神奇功能。

首先，配一个数据库配置：

import org.apache.ibatis.mapping.DatabaseIdProvider;
import org.apache.ibatis.mapping.VendorDatabaseIdProvider;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import java.util.Properties;

@Configuration
public class DatabaseConfig {
    /**
     * 自动识别使用的数据库类型
     * 在mapper.xml中databaseId的值就是跟这里对应，
     * 如果没有databaseId选择则说明该sql适用所有数据库
     * */
    @Bean
    public DatabaseIdProvider getDatabaseIdProvider(){
        DatabaseIdProvider databaseIdProvider = new VendorDatabaseIdProvider();
        Properties properties = new Properties();
        properties.setProperty("Oracle","oracle");
        properties.setProperty("MySQL","mysql");
        properties.setProperty("DB2","db2");
        properties.setProperty("Derby","derby");
        properties.setProperty("H2","h2");
        properties.setProperty("HSQL","hsql");
        properties.setProperty("Informix","informix");
        properties.setProperty("MS-SQL","ms-sql");
        properties.setProperty("PostgreSQL","postgresql");
        properties.setProperty("Sybase","sybase");
        properties.setProperty("Hana","hana");
        databaseIdProvider.setProperties(properties);
        return databaseIdProvider;
    }
}

然后就可以直接在mybatis文件中通过databaseId属性，来指定这个sql在什么数据库情况下执行：

    <select id="listByName" parameterType="com.yuxx.pub.service.base.domain.vo.BaseAreaVo"
            resultMap="com.yuxx.pub.service.base.biz.dao.BaseAreaMapper.BaseAreaResultMap" databaseId="mysql">
        select
        <include refid="BaseArea_Column_List_1"/>
        from base_area a
        <where>
            <if test="areaName != null and areaName !=''">a.AREA_NAME like concat('%',#{areaName},'%') and</if>
            a.area_id in(
                SELECT area_id FROM(
                SELECT
                @ids as _ids,
                ( SELECT @ids := GROUP_CONCAT(area_id)
                FROM base_area
                WHERE FIND_IN_SET(parent_id, @ids)
                ) as cids,
                @l := @l+1 as level
                FROM base_area,
                (SELECT @ids :=#{currUserAreaId}, @l := 0 ) b
                WHERE @ids IS NOT NULL
                ) id, base_area DATA
                WHERE FIND_IN_SET(DATA.area_id, ID._ids)
            )
        </where>
        <if test="rowNum != null and rowNum !=''">
            limit #{rowNum}
        </if>
    </select>
    <select id="listByName" parameterType="com.yuxx.pub.service.base.domain.vo.BaseAreaVo"
            resultMap="com.yuxx.pub.service.base.biz.dao.BaseAreaMapper.BaseAreaResultMap" databaseId="oracle" >
        select
        <include refid="BaseArea_Column_List_1"/>
        from base_area a
        <where>
            <if test="areaName != null and areaName !=''">a.AREA_NAME like concat('%',#{areaName},'%') and</if>
            a.area_id in(
                select
                  area_id
                from
                  base_area
                start with
                  parent_id = #{currUserAreaId}
                connect by prior
                  area_id = parent_id
            )
        </where>
        <if test="rowNum != null and rowNum !=''">
            limit #{rowNum}
        </if>
    </select>

就酱，加上databaseId就可以指定要用的sql，mybatis会根据链接过来的DataSource自动识别。

来源：oschina

链接：https://my.oschina.net/alexjava/blog/4711124

标签

Oracle

MyBatis

mysql