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  • mybatis基础学习1---(配置文件和sql语句)

    1:配置文件(主要配置文件)

    2:配置文件(引入)

    3:sql语句解析:

    <mapper namespace="/">
    <!-- 1 -->根据id查对象
    <select id="findById" parameterType="int" resultType="jike.book.pojo.JiKeUser">
    select *
    from jikeUser where id=#{id}
    </select>
    <!-- 1 -->
    <!-- 2 -->插入对象
    <insert id="insertUser" parameterType="JiKeUser" statementType="PREPARED"
    keyProperty="id" useGeneratedKeys="true">
    insert into JikeUser
    (userName,password) values
    (#{userName},#{password})
    </insert>
    <!-- 2 -->
    <!-- 3 -->更改对象
    <update id="updateUser" parameterType="JiKeUser">
    UPDATE JiKeUser SET
    userName=#{userName},
    password=#{password}
    WHERE id = #{id}
    </update>
    <!-- 3 -->
    <!-- 4 -->登录选择
    <select id="loginSelect" resultType="JiKeUser" parameterType="hashmap">
    select * from JikeUser where userName=#{userName} and
    password=#{password}
    </select>
    <!-- 4 -->
    <!-- 5 -->登录选择
    <select id="login2" resultType="JiKeUser" parameterType="JiKeUser">
    select *
    from JikeUser where userName=#{userName} and password=#{password}
    </select>
    <!-- 5 -->
    <!-- 6 -->对象列表查询
    <select id="selectJiKeUserList" resultType="JiKeUser">
    select * from
    JikeUser
    </select>
    <!-- 6 -->


    <!-- 7 --><!--和下面有联系-->
    <resultMap id="JiKeUserMap" type="JiKeUser">
    <id property="id" column="id" />
    <result property="userName" column="userName" />
    <result property="password" column="password" />
    </resultMap>
    <!-- 7 -->


    <!-- 8 -->对象Map查询<!--和上面有联系-->
    <select id="selectUsers" resultMap="JiKeUserMap">
    select id, userName, password
    from JiKeUser
    </select>
    <!-- 8 -->
    </mapper>

    ----------------------------------------------------------------------------------------------------------------

     4:mybatis的sql语句区分大小写

    例:

    select * from JikeUser where userName=#{userName} and
    password=#{password}

    大括号里的字段必须和Bean定义的字段大小写一致(因为靠java的setter传值)。外面的字段要和建表字段一致(如下图)

    ---------------------------------------------------------------------------------------------------------------------

    5:mybatis配置文件引入。下面类和包引用写反了

    直接引用xml文件

    <mappers>  
         <mapper resource="com/yu/res/UserMapper.xml" />  
    </mappers>

    通过绝对路径引用,注意在绝对路径前加上:“file:///”

    <mappers>  
         <mapper url="file:///D:/workspace/mywork/MyBatis/src/com/yu/res/UserMapper.xml"/> 
    </mappers>

    引用mapper接口对象的方式:

    <mappers>  
         <mapper resource="com.yu.mapper.UserMapper" />  
    </mappers>

    引用mapper接口包的方式:

    <mappers>  
         <package name="com.yu.mapper"/>
    </mappers>

     6:包定义注意事项比较

    引入主配置文件(MyBatisConfig.xml)要加包名

    ----------------------------------------------------------------------------------------------------------------------

    主配置文件引其他配置文件也要加包名

     

    =============================================================

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  • 原文地址:https://www.cnblogs.com/kaiwen/p/6440793.html
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