<typeAliases> <package name="com.entity"/> </typeAliases>3.传入多个对象可以通过@Parm注解给参数起别名：
public void show(@Param("") String name, String pwd);
4.模糊查找：
select * from student where stuName like concat('%',#{stuName},'%')
5.如果只是用MyBatis，那么每写一个Mapper文件要在核心配置文件里面加载：
<mappers> <mapper resource="com/mapper/StudentMapper.xml"></mapper> <mapper resource="com/mapper/GradeMapper.xml"></mapper> </mappers>6.结果集映射：实体类属性如果跟数据库字段名不一样，则默认匹配失败，可以
1.给字段起别名：SELECT stuName as '姓名' FROM `student` 2.使用resultMap <resultMap type="Student" id="BaseMap"> <id column="stuId" property="stuId"/> <result column="stuName" property="stuName"/> <result column="stuAge" property="stuAge"/> <result column="stuBirth" property="stuBirth"/> </resultMap> 7.sql映射文件中，resultMap可以继承，也可以引用 <resultMap type="Student" id="studentResultMap" extends="BaseMap"> </resultMap> <resultMap type="Grade" id="GradeMap" extends="BaseMap"> <collection property="students" ofType="Student" resultMap="com.dao.StudentDAO.BaseMap </resultMap>MyBatis下载地址 中文文档8，查询返回的是个普通实体类使用resultType，否则用resultMap 9.多对一的映射方式，association标签
<resultMap type="Student" id="studentResultMap" extends="BaseMap"> <association property="grade" javaType="Grade"> <id column="gradeId" property="gradeId"/> <result column="gradeName" property="gradeName"/> </association> </resultMap>10.一对多映射，collection标签 11.动态sql
1 if标签：
2 <select id="findActiveBlogLike" resultType="Blog">
4 SELECT * FROM BLOG WHERE 1 = 1
5 <if test="title != null">
6 AND title like #{title}
7 </if>
8 <if test="author != null and author.name != null">
9 AND author_name like #{author.name}
10 </if>
11 </select>
12
13 choose、when、otherwise标签：传入了 “title” 就按 “title” 查找，传入了 “author”
14 就按 “author” 查找的情形。若两者都没有传入，就返回标记为 featured 的 BLOG
15
16 <select id="findActiveBlogLike" resultType="Blog">
18 SELECT * FROM BLOG WHERE state = ‘ACTIVE’
19 <choose>
20 <when test="title != null">
21 AND title like #{title}
22 </when>
23 <when test="author != null and author.name != null">
24 AND author_name like #{author.name}
25 </when>
26 <otherwise>
27 AND featured = 1
28 </otherwise>
29 </choose>
30 </select>
31
32 trim、where、set标签
33
34 where 元素只会在子元素返回任何内容的情况下才插入 “WHERE” 子句。
35 而且，若子句的开头为 “AND” 或 “OR”，where 元素也会将它们去除。
36 <select id="findActiveBlogLike" resultType="Blog">
38 SELECT * FROM BLOG
39 <where>
40 <if test="state != null">
41 state = #{state}
42 </if>
43 <if test="title != null">
44 AND title like #{title}
45 </if>
46 <if test="author != null and author.name != null">
47 AND author_name like #{author.name}
48 </if>
49 </where>
50 </select>
51
52 set 元素会动态地在行首插入 SET 关键字，
53 并会删掉额外的逗号（这些逗号是在使用条件语句给列赋值时引入的）
54
55 <update id="updateAuthorIfNecessary">
56 update Author
57 <set>
58 <if test="username != null">username=#{username},</if>
59 <if test="password != null">password=#{password},</if>
60 <if test="email != null">email=#{email},</if>61 <if test="bio != null">bio=#{bio}</if>
62 </set>
63 where id=#{id}
64 </update>
65
66 foreach,collection:如果传入的是数组，用array，如果是list，用list
67
68 <select id="selectPostIn" resultType="domain.blog.Post">
69 SELECT *
70 FROM POST P
71 WHERE ID in
72 <foreach item="item" index="index" collection="list"
73 open="(" separator="," close=")">
74 #{item}
75 </foreach>
76 </select>
12.共同的sql语句可以放在一个sql标签中，用include引用
<sql id="sql">
</sql>
<insert id="">
<include refid="sql"></include>
</insert>