mybatis 初识2

关联关系 ：相对应参数，再查找一次

<resultMap type="Student" id="StudentResult"><id property="id" column="id"/><result property="name" column="name"/><result property="age" column="age"/><association property="address" column="addressId" select="com.java1234.mappers.AddressMapper.findById"></association><association property="grade" column="gradeId" select="com.java1234.mappers.GradeMapper.findById"></association></resultMap>

动态sql：

样例：

<mapper namespace="com.java1234.mappers.StudentMapper"><resultMap type="Student" id="StudentResult"><id property="id" column="id"/><result property="name" column="name"/><result property="age" column="age"/></resultMap><insert id="insertStudent" parameterType="Student">insert into t_student values(null,#{name},#{age},#{pic},#{remark});</insert><select id="getStudentById" parameterType="Integer" resultType="Student">select * from t_student where id=#{id}</select><select id="searchStudents6" resultMap="StudentResult">select * from t_student where name like #{param1} and age=#{param2}</select><select id="searchStudents" parameterType="Map" resultMap="StudentResult">select * from t_student  where gradeId=#{gradeId} <if test="name!=null"> and name like #{name} </if> <if test="age!=nulll"> and age=#{age} </if></select><select id="searchStudents2" parameterType="Map" resultMap="StudentResult">select * from t_student  <choose> <when test="searchBy=='gradeId'"> where gradeId=#{gradeId} </when> <when test="searchBy=='name'"> where name like #{name} </when> <otherwise> where age=#{age} </otherwise> </choose> </select><select id="searchStudents3" parameterType="Map" resultMap="StudentResult">select * from t_student  <where> <if test="gradeId!=null"> gradeId=#{gradeId} </if> <if test="name!=null"> and name like #{name} </if> <if test="age!=nulll"> and age=#{age} </if> </where></select><select id="searchStudents4" parameterType="Map" resultMap="StudentResult">select * from t_student  <trim prefix="where" prefixOverrides="and|or"> <if test="gradeId!=null"> gradeId=#{gradeId} </if> <if test="name!=null"> and name like #{name} </if> <if test="age!=nulll"> and age=#{age} </if> </trim></select><select id="searchStudents5" parameterType="Map" resultMap="StudentResult">select * from t_student  <if test="gradeIds!=null"> <where> gradeId in  <foreach item="gradeId" collection="gradeIds" open="(" separator="," close=")">  #{gradeId} </foreach> </where> </if></select><update id="updateStudent" parameterType="Student">update t_student<set> <if test="name!=null"> name=#{name}, </if> <if test="age!=null"> age=#{age}, </if></set>where id=#{id}</update></mapper>