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
<insert>
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[<=]]>
:
<where>：
<if test="sal != null">
and sal <![CDATA[<=]]>#{sal} //and，or会自动给去掉
</where>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
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
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]:
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
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>)；
<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]:
<sql id="sqlid">
select * from emp
</sql>
<include refid="sqlid"></include>
[bind]标签
<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：
<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)
