<select id="queryLikeByStuName2" parameterType="map" resultMap="studentMap">
　　select * from student 
　　<where>
　　　　<if test="studentNo != null and studentNo != ‘‘" >
　　　　　　and StudentNo = #{studentNo}    
　　　　</if>
　　　　<if test="studentName != null and studentName != ‘‘" >
　　　　　　and StudentName like CONCAT(‘%‘,#{studentName},‘%‘)
　　　　</if>
　　</where>
</select>

<select id="queryByTrim" parameterType="map" resultMap="studentMap">
　　select * from student
　　<trim prefix="where" prefixOverrides="and | or">
　　　　<if test="studentName != null and studentName != ‘‘">and StudentName like CONCAT("%",#{studentName},"%" )</if>
　　　　<if test="phone !=null and phone !=‘‘">and Phone=#{phone}</if>
　　　　</trim>
</select>
==>注意:每一个if内语句前都要加 and 
<if test="studentName != null and studentName != ‘‘">and StudentName like CONCAT("%",#{studentName},"%" )</if>
　　==>使用 bind元素 <bind name="pattern" value=" ‘%‘ + studentName + ‘%‘ " />
<if test="studentName != null and studentName != ‘‘">and StudentName like #{pattern} </if>

<update id="updateStudent" parameterType="Student">
　　update student 
<set>
　　<if test="loginPwd != null and loginPwd != ‘‘">LoginPwd=#{loginPwd},</if>
　　<if test="studentName != null and studentName != ‘‘">StudentName=#{studentName},</if>
　　<if test="sex != null and sex != ‘‘">Sex=#{sex},</if>
　　<if test="gradeId !=null and gradeId != ‘‘">GradeId=#{gradeId},</if>
　　<if test="phone !=null and phone !=‘‘">Phone=#{phone},</if>
</set>
　　where StudentNo = #{studentNo}
</update>

<update id="updateByTrim" parameterType="Student">
　　update student
　　<trim prefix="set" suffixOverrides=",">
　　　　<if test="loginPwd != null and loginPwd != ‘‘">LoginPwd=#{loginPwd},</if>
　　　　<if test="studentName != null and studentName != ‘‘">StudentName=#{studentName},</if>
　　　　<if test="sex != null and sex != ‘‘">Sex=#{sex},</if>
　　　　<if test="gradeId !=null and gradeId != ‘‘">GradeId=#{gradeId},</if>
　　　　<if test="phone !=null and phone !=‘‘">Phone=#{phone},</if>
　　</trim>
　　where StudentNo = #{studentNo}
</update>

<select id="queryByIn" parameterType="java.util.List" resultMap="studentMap">
　　select * from student where StudentNo in
　　<foreach collection="list" item="list" open="(" separator="," close=")">
　　　　#{list}
　　</foreach>
</select>

@Test
public void queryByIn(){
　　List<Integer> list = new ArrayList<Integer>();
　　list.add(1001);
　　list.add(1003);
　　list.add(1005);
　　List<Student> stuList = studentDao.queryByIn(list);
　　for (Student stu : stuList) {
　　　　System.out.println(stu);
　　}
}

<select id="queryByIn2" parameterType="java.lang.Integer" resultMap="studentMap">
　　select * from student where StudentNo in
　　<foreach collection="array" item="array" open="(" separator="," close=")">
　　　　#{array}
　　</foreach>
</select>

@Test
public void queryByIn2(){
　　Integer[] arrays = {1001,1003,1005};
　　List<Student> stuList = studentDao.queryByIn2(arrays);
　　for (Student stu : stuList) {
　　　　System.out.println(stu);
　　}
}

Map<String,Integer> map = new HashMap<String,Integer>();
map.put("pageNo", pageNo);
map.put("pageSize", pageSize);
List<Student> list = studentDao.listStudentByPage(map);

<select id="listStudentByPage" parameterType="map" resultMap="studentMap">
　　SELECT * FROM student WHERE id LIMIT #{pageNo},#{pageSize}
</select>

<select id="listStudentByChoose" parameterType="Student" resultMap="studentMap">
　　SELECT * FROM student WHERE city = ‘北京‘
　　<choose>
　　　　<when test="stuName != null">
　　　　　　and name like CONCAT(‘%‘,#{stuName},‘%‘)
　　　　</when>
　　　　<when test="stuAge != null">
　　　　　　and age = #{stuAge}
　　　　</when>
　　　　<otherwise>
　　　　　　and gradeId = 1703
　　　　</otherwise>
　　</choose>
</select>