mybatis基础笔记三

<select id= "queryStuByNOrAWishSQLTag"    parameterType= "student" resultType= "student"  >
select stuno,stuname,stuage from student
<if test= "stuName !=null and stuName!=''  " > 
and stuname = #{stuName}
<if test= "stuAge !=null and stuAge!=0  " > 
 and stuage = #{stuAge}
****

<select id= "queryStudentsWithNosInGrade"   parameterType= "grade"  resultType= "student" >
   select * from student
    <if test= "stuNos!=null and stuNos.size>0" >
     <foreach collection= "stuNos"  open= " and  stuno in ("  close= ")"  
     item= "stuNo"  separator= "," >   
     #{stuNo}
   ****

<select id= "queryStudentsWithArray"   parameterType= "int[]"  resultType= "student" >
   select * from student
    <if test= "array!=null and array.length" >
     <foreach collection= "array"  open= " and  stuno in ("  close= ")"  
     item= "stuNo"  separator= "," >   
     #{stuNo}
****

<select id= "queryStudentsWithList"   parameterType= "list"  resultType= "student" >
   select * from student
    <if test= "list!=null and list.size>0" >
     <foreach collection= "list"  open= " and  stuno in ("  close= ")"  
     item= "stuNo"  separator= "," >   
     #{stuNo}
****

<select id= "queryStudentsWithObjectArray"   parameterType= "Object[]"  resultType= "student" >
   select * from student
   <!--如果sql片段和  引用处不在同一个文件中，则需要 在refid 引用时  加上namespace:   namespace.id
    -->
   <include refid= "objectArrayStunos" >

<sql id= "objectArrayStunos" >
    <if test= "array!=null and array.length>0" >
     <foreach collection= "array"  open= " and  stuno in ("  close= ")"  
     item= "student"  separator= "," >   
     #{student.stuNo}
****

<select id= "queryStudentsWithObjectArray"   parameterType= "Object[]"  resultType= "student" >
   select * from student
   <!--如果sql片段和  引用处不在同一个文件中，则需要 在refid 引用时  加上namespace:   namespace.id
    -->
   <include refid= "objectArrayStunos" >
****

SqlSessionFactory sessionFacotry = new SqlSessionFactoryBuilder().build(reader,"development") ;
SqlSession session = sessionFacotry.openSession() ;
StudentMapper studentMapper = session.getMapper(StudentMapper.class) ;
StudentBusiness studentBusiness = studentMapper.queryStudentByNoWithOO(2) ;//接口中的方法->SQL语句
System.out.println(studentBusiness);****

Student queryStudentByNoWithOO2(int stuNo);
SqlSession session = sessionFacotry.openSession();
StudentMapper studentMapper = session.getMapper(StudentMapper.class);
Student student = studentMapper.queryStudentByNoWithOO2(2);// 接口中的方法->SQL语句
System.out.println(student);****

一对一：association****
一对多：collection****
表：student studentclass  (关联：classid)
类：student studentClass  (关联：List students )
select  c.,s. from student s
inner join studentclass c
on c.classid = s.classid
where c.classid = 1;

StudentClass queryClassAndStudents(int classId);StudentMapper
StudentMapper studentMapper = session.getMapper(StudentMapper.class);
// 班级
StudentClass studentClass = studentMapper.queryClassAndStudents(1);
// System.out.println(studentClass);
System.out.println(studentClass.getClassId() + "," + studentClass.getClassName());
// 班级对应的学生
List students = studentClass.getStudents();
for (Student student : students) {
System.out.println(student.getStuNo() + "," + student.getStuName() + "," + student.getStuAge());
}