SelectKey在Mybatis中是為了解決Insert數據時不支持主鍵自動生成的問題，他可以很隨意的設置生成主鍵的方式。

Mapper(Oracle)

<insert id="insertWxshLogOut"  parameterType="java.util.HashMap">
    <selectKey resultType="java.lang.String" order="BEFORE" keyProperty="id">
        select wxsh_seq.nextval as id from dual
    </selectKey>
    INSERT INTO WXSH_LOG_OUT
    (ID,
     OUT_NO,
     USER_ID,
     FILE_NAME,
     CREATE_AT,
     IP,
     CONTENT,
     OUT_NUM,
     UNIT_NO,
     STATUS)
    VALUES
        (#{id},
         #{out_no},
         #{user_id},
         #{file_name},
         SYSDATE,
         #{ip},
         #{content},
         #{out_num},
         #{unit_no},
         #{status})
</insert>

Service

public int addWxshLogOut(Map map) {
    try {
        DataSourceTypeManager.set(DataSources.GJT);
        welfareConfirmMapper.insertWxshLogOut(map);
        return Integer.parseInt(String.valueOf(map.get("id")));
    } catch (Exception e) {
        logger.error(e.getMessage());
    }
    return 0;
}

map中會增加返回的主鍵id