Java_01

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

<!--参数占位符#{} ：执行SQL时，会将 #{} 占位符替换为？，将来自动设置参数值。从上述例子可以看出使用#{} 底层使用的是 PreparedStatement-->
<!--    转意字符 &lt; 就是 < 的转义字符。                -->
<!--    还可以用!<![CDATA[                            -->
<!--    <                                           -->
<!--    ]]>  来表达转意字符                                -->
<!--namespace名称空间-->
<mapper namespace="com.itheima.mapper.BrandMapper">


    <!--查询数据库全部信息-->
        <select id="selectAll" resultType="brand">
            select *
            from tb_brand;
        </select>


<!--查询id为几的全部信息-->
    <select id="selectById" resultType="com.itheima.pojo.Brand">
        select *
        from tb_brand where id  = #{id};
    </select>


<!--模糊查询，多条件查询-->
    <select id="selectByCondition" resultType="com.itheima.pojo.Brand">
            select *
            from tb_brand
            <where>
                <if test="status != null">
                    and status = #{status}
                </if>
                <if test="company_name != null and company_name != '' ">
                    and company_name like #{company_name}
                </if>
                <if test="brand_name != null and brand_name != ''">
                    and brand_name like #{brand_name}
                </if>
            </where>
    </select>


<!--单条件查询-->
    <select id="selectByConditionSingle" resultType="com.itheima.pojo.Brand">
        select *
        from tb_brand
        <where>
            <choose><!--相当于switch-->
                <when test="status != null"><!--相当于case-->
                    status = #{status}
                </when>
                <when test="company_name != null and company_name != '' "><!--相当于case-->
                    company_name like #{company_name}
                </when>
                <when test="brand_name != null and brand_name != ''"><!--相当于case-->
                    brand_name like #{ brand_name}
                </when>
            </choose>
        </where>
    </select>


<!--添加-->
<!--    这个sql语句没用,与本例子无关,是关联到第二个表<<添加订单>>,一个订单又多个商品信息,主键id传给后面的商品信息-->
    <insert id="addOrder" useGeneratedKeys="true" keyProperty="id">
        insert into tb_order (payment,payment_type,status)
        values (#{payment}, #{payment_type}, #{status});
    </insert>
    <!--    这个sql语句没用,与本例子无关,是关联到第一个表<<添加该订单下的商品信息>>,获得前面的id-->
    <insert id="addOrderItem" >
        insert into tb_order_item (goods_name,goods_price,count,order_id)
        values (#{goods_name}, #{goods_price}, #{count},#{order_id});
    </insert>
    <insert id="add" useGeneratedKeys="true" keyProperty="id">
        insert into tb_brand (brand_name, company_name, ordered, description, status)
        values (#{brand_name}, #{company_name}, #{ordered}, #{description}, #{status});
    </insert>


<!--修改-->
    <update id="update">
        update tb_brand
        <set>
        <if test="brand_name != null and brand_name != ''">
            brand_name = #{brand_name},
        </if>
        <if test="company_name != null and company_name != ''">
            company_name = #{company_name},
        </if>
            <if test="ordered != null">
                ordered = #{ordered},
            </if>
            <if test="description != null and description != ''">
                description = #{description},
            </if>
            <if test="status != null">
                status = #{status}
            </if>
        </set>
        where id = #{id};
    </update>


<!--删除-->
    <delete id="deleteById">
        delete from tb_brand where id = #{id};
    </delete>



</mapper>