VIP23/04maven/mybatis/src/main/resources/BookMapper.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.sf.mapper.BookMapper">


<!--    添加图书-->
    <insert id="addBook" parameterType="book">
        insert into book (book_id , book_name , price) values (#{bookId},#{bookName},#{price})
    </insert>

<!--    更新图书-->

    <update id="updateBook" parameterType="book">
        update book set book_name = #{bookName} , price = #{price} where book_id = #{bookId}
    </update>

<!--    删除图书-->
    <delete id="deleteBook" parameterType="integer">
        delete from  book where book_id = #{bookId}
    </delete>

<!--    查询图书列表-->

    <select id="getBookList" resultType="book">
        select * from book
    </select>

<!--查询图书详情根据图书的id-->
<select id="getBookInfo" resultType="book">
    select * from book where book_id = #{bookId}
</select>


    <select id="getBookListWithIdorNameOrPrice" resultType="book">
        select * from book where price = #{price} and book_name=#{bookName}
    </select>

<!-- <if test="bookId != null">
      and  book_id = #{bookId}
     </if>
     <if>标签:作为条件判断
     test="bookId != null"  : 是判断入参中的bookId 是否为空
                                如果不等于空 就拼接查询条件
                                等于空,就不拼接查询条件
     <where>标签去除and和or  帮助我们解决多条件查询sql条件拼接问题
     -->
    <select id="getBookListWithIdorNameOrPrice2" parameterType="book" resultType="book">
        select * from book <where>
        <if test="bookId != null">
            and  book_id = #{bookId}
        </if>
        <if test="bookName != null">
            and  book_name=#{bookName}
        </if>
        <if test="price != null">
            and  price = #{price}
        </if>
        </where>
    </select>

    <update id="updateBook2" parameterType="book">
        update book <set>
        <if test="bookName != null">book_name = #{bookName} , </if>
        <if test="price != null">price = #{price} </if>
    </set>
     where book_id = #{bookId}
    </update>


    <select id="getBookListWithIdorNameOrPrice3" parameterType="book" resultType="book">
        select  *  from   book  where
        <choose>
            <when test="bookName != null">book_name = #{bookName}</when>
            <when test="price != null">price = #{price}</when>
          <otherwise>
              book_id = #{bookId}
          </otherwise>
        </choose>

    </select>
</mapper>