认识达内从这里开始

1.参数注入
1.1用#{0},#{1}的形式，0代表第一个参数，1代表第二个参数
public List<RecordVo> queryList(String workerId, Integer topNum);

<select id="queryList" resultType="com.demo.RecordVo">
SELECT ID id, WORKER_ID workerId, UPDATE_DATE updateDate
FROM USER_RECORDS t
WHERE t.WORKER_ID = #{0}
LIMIT #{1}
</select>
1.2Map或者封装对象,workerId为map里面的键；如果是对象则workerId为对象中的属性，这种方法非常常用
public Integer queryCountByWorkerId(Map queryParam);
<select id="queryCountByWorkerId" parameterType="java.util.Map" resultType="java.lang.Integer">
SELECT COUNT(1)
FROM tableName F
WHERE F.WORKER_ID = #{workerId}
</select>

1.3注解
public Integer queryCountByWorkerId(@param(“workerId”)String workerId);
<select id="queryCountByWorkerId" parameterType="java.util.Map" resultType="java.lang.Integer">
SELECT COUNT(1)
FROM tableName F
WHERE F.WORKER_ID = #{workerId}
</select>
2.返回
2.1映射<!-- 实体类与表字段对应 -->
<resultMap type="com.demo.DataModule" id="dataModule">
<result column="ID" property="id" />
<result column="CREATE_DATE" property="createDate" />
<result column="WORKERID" property="workerId" />
<result column="UPDATE_DATE" property="updateDate" />
<result column="STATUS" property="status" />
</resultMap>
<select id="queryAll" resultType="dataModule">
select ID,CREATE_DATE,WORKERID from tableName 
</select>

这种方式查询语句查询的字段直接就是数据库里面的字段就好了，就定义映射的column
2.2直接返回对象
<select id="queryAll" resultType="com.demo.DataModule">
select ID id,CREATE_DATE createDate,WORKERID workerId from tableName 
</select>

这里查询返回的字段别名必须对应返回对象中的属性

3.执行原生sql
3.1sql参数：
public class ParamVo {

private String sql;
//getter setter 省略

}

3.2接口：
/**
* @功能描述: 创建
* @param vo
* @return
*/
public int excuteCreateSql(ParamVo vo);

/**
* @功能描述: 查询
* @param vo
* @return
*/
public List<Map<String, Object>> excuteSelectSql(ParamVo vo);

3.3xml:
<update id="excuteCreateSql">
${sql}
</update>
${}不编译sql直接执行，如果用#{sql}可能报错

<select id="excuteSelectSql" resultType="java.util.Map">
${sql}
</select>
这里不知道返回类型用map或者hashmap作为返回

4.include:有时候两个方法要返回的字段都一样或者where子句一样，这样为了避免重复写代码，就抽出来用include
4.1定义子句相同部分
<sql id="queryChild">
FROM tableName1 F
RIGHT JOIN tableName2 C ON F.WORKER_ID = C.WORKER_ID 
WHERE F.STATUS = 1 AND F.WORKER_ID = #{workerId}
ORDER BY C.CREATE_DATE DESC 
</sql>
4.2引用
<select id="queryCountByWorkerId" parameterType="java.util.Map" resultType="java.lang.Integer">
SELECT COUNT(1)
<include refid="queryChild"/>
</select>
<select id="queryListByWorkerId" parameterType="java.util.Map" resultType="com.demo.RecordVo">
SELECT ID id, WORKER_ID workerId, UPDATE_DATE updateDate,......
<include refid="queryChild"/>
</select>