Mybatis 動態sql

 詳情參照mybatis官方文檔：https://mybatis.org/mybatis-3/zh/index.html

<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.hz.platform.demo.dao.StudentDao">
    <!-- 中文文檔https://mybatis.org/mybatis-3/zh/dynamic-sql.html-->
    <resultMap id="studentResult" type="com.hz.platform.demo.entity.Student">
        <result column="stu_name" property="stuName" jdbcType="VARCHAR"/>
        <result column="address" property="address" jdbcType="VARCHAR"/>
        <result column="age" property="age" jdbcType="INTEGER"/>
        <result column="birthday" property="birthday" jdbcType="TIMESTAMP"/>
        <result column="gender" property="gender" jdbcType="VARCHAR"/>
    </resultMap>
    <!-- 動態sql測試  where if  -->
    <select id="findAll" resultMap="studentResult">
        select stu_name,address,age,birthday,gender from student
        <trim prefix="where" prefixOverrides="AND|OR">
            <if test="stuName != '' and stuName != null">
                and stu_name = #{stuName,jdbcType=VARCHAR}
            </if>
            <if test="address != '' and address != null">
                and address = #{address,jdbcType=VARCHAR}
            </if>
        </trim>
    </select>
    <!--    有時我們不想應用到所有的條件語句，而只想從中擇其一項。針對這種情況，MyBatis 提供了 choose 元素，它有點像 Java 中的 switch 語句。-->
    <select id="find1" resultMap="studentResult">
        select stu_name,address,age,birthday,gender from student
        <where>
            <choose>
                <when test="stuName != '' and stuName != null">
                    and stu_name = #{stuName,jdbcType=VARCHAR}
                </when>
                <when test="address != '' and address != null">
                    and address = #{address,jdbcType=VARCHAR}
                </when>
                <otherwise>
                    AND gender = "男"
                </otherwise>
            </choose>
        </where>
    </select>
    <insert id="insertStudent" parameterType="com.hz.platform.demo.entity.Student">
        insert into student
        <trim prefix="(" suffix=")" suffixOverrides=",">
            uuid,
            <if test="stuName != null and stuName != ''">
                stu_name,
            </if>
            <if test="address != null and address != ''">
                address,
            </if>
            <if test="age != null and age != ''">
                age,
            </if>
            <if test="birthday != null">
                birthday,
            </if>
            <if test="gender != null and gender != ''">
                gender,
            </if>
        </trim>
        <trim prefix="VALUES(" suffix=")" suffixOverrides=",">
            (SELECT uuid()),
            <if test="stuName != null">
                #{stuName,jdbcType=VARCHAR},
            </if>
            <if test="address != null">
                #{address,jdbcType=VARCHAR},
            </if>
            <if test="age != null">
                #{age,jdbcType=INTEGER},
            </if>
            <if test="birthday != null">
                #{birthday,jdbcType=TIMESTAMP},
            </if>
            <if test="gender != null">
                #{gender,jdbcType=VARCHAR},
            </if>
        </trim>
    </insert>

    <update id="updateStudent" parameterType="com.hz.platform.demo.entity.Student">
        update student
        <trim prefix="set" suffixOverrides=",">
            <if test="stuName != null">
                stu_name = #{stuName,jdbcType=VARCHAR},
            </if>
            <if test="address != null">
                address = #{address,jdbcType=VARCHAR},
            </if>
            <if test="age != null">
                age = #{age,jdbcType=INTEGER},
            </if>
            <if test="birthday != null">
                birthday = #{birthday,jdbcType=TIMESTAMP},
            </if>
            <if test="gender != null">
                gender = #{gender,jdbcType=VARCHAR},
            </if>
        </trim>
        <trim prefix="where" prefixOverrides="AND|OR" suffixOverrides=",">
            uuid =#{uuid,jdbcType=VARCHAR}
        </trim>
    </update>
</mapper>