2024/03/11（2024春季）

今日学习web时长一小时

代码行数大概100多行

博客数量一篇

今天主要完成了通过xml配置文件完成了数据的批量删除和根据指定字段查询

关键的应用标签就是<where><if>来完成指定字段的SQL语句的成立与否

<foreach>来完成不定个数主键来删除数据

    //    利用xml来完成条件查询
    public List<Emp> list(String name, Short gender, LocalDate begin, LocalDate end);


    /*根据id来完成单个或批量删除员工*/
    void delete(List<Integer> ids);

<?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.itheima.tlias.mapper.EmpMapper">
    <update id="update">
        update emp
        <set>
            <if test="name!=null">
                username=#{username},
            </if>
            <if test="password!=null">
                password=#{password},
            </if>
            <if test="name!=null">
                name=#{name},
            </if>
            <if test="gender!=null">
                gender=#{gender},
            </if>
            <if test="image!=null">
                image=#{image},
            </if>
            <if test="job!=null">
                job=#{job},
            </if>
            <if test="entrydate!=null">
                entrydate=#{entrydate},
            </if>
            <if test="deptId!=null">
                dept_id=#{deptId},
            </if>
            <if test="updateTime!=null">
                update_time=#{updateTime}
            </if>
        </set>
        where id=#{id}
    </update>
    <select id="list" resultType="com.itheima.tlias.pojo.Emp">
        select id,
        username,
        password,
        name,
        gender,
        image,
        job,
        entrydate,
        dept_id,
        create_time,
        update_time
        from emp
        <where>
            <if test="name!=null and name!=''">
                name like concat('%',#{name},'%')
            </if>
            <if test="gender!=null">
                and gender=#{gender}
            </if>
            <if test="begin!=null and end !=null">
                and entrydate between #{begin} and #{end}
            </if>
        </where>
        order by update_time desc
    </select>
    <delete id="delete">
        delete from emp where id in
        <foreach collection="ids" separator="," close=")" open="(" item="id">
            #{id}
        </foreach>
    </delete>
</mapper>

等