Mapper.xml映射文件

Mapper.xml映射文件：

<select> resultType如果返回的是集合，那么应该设置为集合包含的类型而不是集合本身的类型

如果参数类型是pojo类型，参数名必须是pojo中的属性名

session.commit();

session = factory.openSession();

driver:com.mysql.jdbc.Driver

url:jdbc:mysql://127.0.0.1:3306/test

动态sql：

小于号

<![CDATA[<=]]>

XML 复制代码

<where>：
<if test="sal != null">
and sal <![CDATA[<=]]>#{sal}         //and，or会自动给去掉
</where>

XML 复制代码

choose when otherwise：
when otherwise中只走一个
select * from emp where
<choose>
    <when test="sal != null">
        sal <![CDATA[<=]]> #{sal}
    </when>
    <when test="ename != null">
        ename like concat('%',#{ename},'%')
    </when>
    <otherwise>
        deptno=#{deptno}
    <otherwise>
</choose>

trim标签组合 if标签主要功能可以在自己包含的内容前面加上某些前缀，也可以在其后加上某些后缀，与之对应的属性是prefix和suffix；

可以把包含内容的首部某些内容覆盖，即忽略，也可以把尾部的某些内容覆盖，对应的属性是prefixOverrides和suffixOverrides

XML 复制代码

insert into emp
<trim prefix="("  suffix=")" suffixOverrides = ",">
    <if test = "empno != null">
        empno,
    <if test = "ename != null">
        ename,
    <if test = "mgr != null">
        mgr,
    <if test = "sal != null">
        sal,
    <if test = "deptno != null">
        deptnol,
</trim>
values
<trim prefix="("  suffix=")" suffixOverrides = ",">
    <if test = "empno !=null">
        #{empno},
    <if test = "ename != null">
        #{ename},
    <if test = "mgr != null">
        #{mgr},
    <if test = "sal != null">
        #{sal},
    <if test = "deptno != null">
        #{deptnol},
</trim>

<set>标签：如果包含的语句以逗号结束会把逗号省略掉

XML 复制代码

update   emp
<set>
    <if test="sal != null">
        sal=#{sal},
    </if>
    <if test="mgr != null">
        mgr=#{mgr},
    </if>
    <if test="ename != null">
        ename=#{ename},
    </if>
</set>
<where>
    <if test="empno != null">
        and empno = #{empno}
    </if>
    <if test="job != null">
        and job =  #{job}
    </if>
</where>

<foreach>主要用在构建in条件中，它可以在SQL语句中迭代一个集合

item 表示集合中每一个元素进行迭代时的别名

index指定一个名字，用于表示在迭代过程中，每次迭代到的位置

[LIST]:

XML 复制代码

select * from emp 
<where>
    <foreach collection = "list" open = "(" close = ")" item="empno" seperator="or">
        empno=#{empno}
    </foreach>
</where>

select * from emp where empno in 
    <foreach collection = "list" open = "(" close = ")" item="empno" seperator=",">
        #{empno}
    </foreach>
</where>

[array]:

paramaterType = List

XML 复制代码

select * from emp where empno in 
    <foreach collection = "array" open = "(" close = ")" item="empno" seperator=",">
        #{empno}
    </foreach>
</where>
[map]:

(Map<String,List<Integer> map>)

多条件复杂查询的时候

List<Emp> selectEmpByMapinfo(Map<String,object>)；

XML 复制代码

<select id = "selectEmpByMapinfo" paramaterType="java.util.Map" resultType="emp">

    select * from emp
    <where>
        deptno=#{deptnokey}
        and
        ename like '%${enamekey}%'
        and
        empno in
        <foreach collection="empnos" open="(" close=")" separator="," item="no">
            #{no}
        </foreach>
    </where>
</select>.

map.put("deptnokey",10)

map.put("enamekey","enamekey")

map.put(empnos,list)

[SQL片段]:

XML 复制代码

<sql id="sqlid">
    select * from emp
</sql>
<include refid="sqlid"></include>

[bind]标签

XML 复制代码

<select>
    <bind name="name" value="'%' + ename + '%'">
    select * from emp
    <where>
        <if test="sal != null">
            and sal <![CDATA[ <= ]]>#{sal]
        </if>
        <if test="ename != null">
            and ename like #{name}
        </if>
    </where>
</select>

resultType实现一对一

多对多：

XML 复制代码

<collection property="ods" ofType="orderDetail" >
</collection>
<association property="items" javaType="items">
</association>

SqlSessionFactory factory;

Inputstream stream = Resources.getResourceasStream("SqlMapConfig.xml");

factory = SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder().build(stream)

page工具类实现分页：page工具类：

PageHelper.startPage((page- 1)* size,size)