<?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="dao.BookMapper">
<resultMap id="BaseResultMap" type="domain.Book">
<id column="id" jdbcType="INTEGER" property="id" />
<result column="title" jdbcType="VARCHAR" property="title" />
<result column="author" jdbcType="VARCHAR" property="author" />
<result column="isbn" jdbcType="VARCHAR" property="isbn" />
<result column="category_id" jdbcType="INTEGER" property="categoryId" />
</resultMap>
<sql id="Base_Column_List">
id, title, author, isbn, category_id
</sql>
<select id="selectByPrimaryKey" parameterType="java.lang.Integer" resultMap="BaseResultMap">
select
<include refid="Base_Column_List" />
from book
where id = #{id,jdbcType=INTEGER}
</select>
<resultMap id="bookResultMap" type="domain.Book" extends="BaseResultMap">
<!-- 關聯屬性多對一一般用的是立即加載(分步查詢)
每次查詢都要通過兩表主鍵和外鍵進行匹配
也就說有多少個類別就查多少次,性能差,我希望能只查找一次全部都出來
fetchType是否立即加載eager就是立即加載,lazy就是懶加載
如果要使用懶加載需要再mybatis.config.xml中
<setting>
<setting name="lazyLoadingEnabled" value="true"/>
<setting name="aggressiveLazyLoading" value="true"/>
</setting>
-->
<association property="category" javaType="Category" column="category_id"
select="dao.CategoryMapper.selectByPrimaryKey" fetchType="eager">
</association>
</resultMap>
<select id="selectAll" resultMap="bookResultMap">
select id, title, author, isbn, category_id from book
</select>
<resultMap id="bookResultMap2" type="domain.Book" extends="BaseResultMap">
<!-- 關聯屬性多對一一般用的是立即加載
這裏跟bookResultMap區別:這裏直接把category的Bean類屬性和數據庫的字段直接連接
-->
<association property="category" javaType="Category" column="category_id">
<!-- 這有個坑爲了防止左外連接查詢的時候多表聯查出現mybatis分不清2個表的id所以給其中一個id加上
一個別名-->
<id property="id" column="catId"/>
<result property="name" column="name"/>
</association>
</resultMap>
<select id="selectAll2" resultMap="bookResultMap2">
<!-- 一次性獲取關聯對象(也就是join fetch)-->
select b.id,
b.title,
b.author,
b.isbn,
b.category_id,
c.id as catId,
c.name
from book b left join category c on b.category_id=c.id
</select>
<!-- 使用resultMap映射實體類和字段之間的一一對應關係 -->
<resultMap id="bookResultMap3" type="domain.Book" extends="BaseResultMap">
<association property="category" javaType="Category">
<id property="id" column="c_id"/>
<result property="name" column="name"/>
</association>
</resultMap>
<!-- 兩表聯查 效率沒有左外連接快但是要比分步速度快-->
<select id="selectAll3" resultMap="bookResultMap3">
select
b.id,
b.title,
b.author,
b.isbn,
b.category_id,
c.id as c_id,
c.name
from book b,category c where b.category_id = c.id
</select>
<delete id="deleteByPrimaryKey" parameterType="java.lang.Integer">
delete from book
where id = #{id,jdbcType=INTEGER}
</delete>
<insert id="insert" keyColumn="id" keyProperty="id" parameterType="domain.Book" useGeneratedKeys="true">
insert into book (title, author, isbn,
category_id)
values (#{title,jdbcType=VARCHAR}, #{author,jdbcType=VARCHAR}, #{isbn,jdbcType=VARCHAR},
#{categoryId,jdbcType=INTEGER})
</insert>
<insert id="insertSelective" keyColumn="id" keyProperty="id" parameterType="domain.Book" useGeneratedKeys="true">
insert into book
<trim prefix="(" suffix=")" suffixOverrides=",">
<if test="title != null">
title,
</if>
<if test="author != null">
author,
</if>
<if test="isbn != null">
isbn,
</if>
<if test="categoryId != null">
category_id,
</if>
</trim>
<trim prefix="values (" suffix=")" suffixOverrides=",">
<if test="title != null">
#{title,jdbcType=VARCHAR},
</if>
<if test="author != null">
#{author,jdbcType=VARCHAR},
</if>
<if test="isbn != null">
#{isbn,jdbcType=VARCHAR},
</if>
<if test="categoryId != null">
#{categoryId,jdbcType=INTEGER},
</if>
</trim>
</insert>
<update id="updateByPrimaryKeySelective" parameterType="domain.Book">
update book
<set>
<if test="title != null">
title = #{title,jdbcType=VARCHAR},
</if>
<if test="author != null">
author = #{author,jdbcType=VARCHAR},
</if>
<if test="isbn != null">
isbn = #{isbn,jdbcType=VARCHAR},
</if>
<if test="categoryId != null">
category_id = #{categoryId,jdbcType=INTEGER},
</if>
</set>
where id = #{id,jdbcType=INTEGER}
</update>
<update id="updateByPrimaryKey" parameterType="domain.Book">
update book
set title = #{title,jdbcType=VARCHAR},
author = #{author,jdbcType=VARCHAR},
isbn = #{isbn,jdbcType=VARCHAR},
category_id = #{categoryId,jdbcType=INTEGER}
where id = #{id,jdbcType=INTEGER}
</update>
</mapper>