首页 > 代码库 > hql查询语句 内存中的情况,fetch迫切查询关键字
hql查询语句 内存中的情况,fetch迫切查询关键字
1 package cn.itcast.hibernate.sh.dao; 2 3 import java.util.ArrayList; 4 import java.util.HashSet; 5 import java.util.List; 6 import java.util.Set; 7 8 import org.hibernate.Query; 9 import org.hibernate.Session; 10 import org.junit.Test; 11 12 import cn.itcast.hiberate.sh.domain.Classes; 13 import cn.itcast.hiberate.sh.domain.Student; 14 import cn.itcast.hibernate.sh.utils.HiberanteUtils; 15 16 /** 17 * 单表 18 * 19 * ????多和多对?? 20 * 21 * 多表的结?? 22 * @author Think 23 * 24 */ 25 public class HQLDao extends HiberanteUtils{ 26 public List<Classes> queryAllClasses(){ 27 Session session = sessionFactory.openSession(); 28 List<Classes> cList = session.createQuery("from Classes").list(); 29 30 31 32 session.close(); 33 for(Classes c:cList) 34 System.out.println(c.getCid()); 35 return cList; 36 } 37 38 public List queryClasses_Properties(){ 39 Session session = sessionFactory.openSession(); 40 List cList = session.createQuery("select cid,cname from Classes").list(); 41 session.close(); 42 return cList; 43 } 44 45 public List<Classes> queryClasses_Constructor(){ 46 Session session = sessionFactory.openSession(); 47 List<Classes> cList = session.createQuery("select new cn.itcast.hiberate.sh.domain.Classes(cname,description) from Classes").list(); 48 session.close(); 49 return cList; 50 } 51 52 public Classes queryClasses_Condition(){ 53 Session session = sessionFactory.openSession(); 54 Query query = session.createQuery("select new cn.itcast.hiberate.sh.domain.Classes(cname,description) from Classes where cid=:cid"); 55 query.setLong("cid", 1L); 56 Classes classes = (Classes)query.uniqueResult(); 57 System.out.println(classes.getCname()); 58 session.close(); 59 return classes; 60 } 61 62 public Classes queryClasses_Condition_2(){ 63 Session session = sessionFactory.openSession(); 64 Query query = session.createQuery("select new cn.itcast.hiberate.sh.domain.Classes(cname,description) from Classes where cid=?"); 65 query.setLong(0, 1L); 66 Classes classes = (Classes)query.uniqueResult(); 67 System.out.println(classes.getCname()); 68 session.close(); 69 return classes; 70 } 71 72 /** 73 * order by,group by,sun,min,max,avg,having等都适用 74 * @return 75 */ 76 77 /** 78 * 子查?? 79 */ 80 public void queryClasses_SubSelect(){ 81 Session session = sessionFactory.openSession(); 82 List<Classes> cList = session.createQuery("from Classes where cid in(select cid from Classes where cid in(1,2,3))").list(); 83 session.close(); 84 } 85 86 public static HQLDao getInstance(){ 87 return new HQLDao(); 88 } 89 90 /*********************************************************************************************/ 91 /** 92 * ?????? 93 * 等??连接 查询出来的机构很?? 94 * 内连?? 95 * 左外连接 96 * 迫切左外连接 97 */ 98 public List<Classes> queryClasses_Student_EQ(){ 99 Session session = sessionFactory.openSession(); 100 List<Classes> cList = session.createQuery("from Classes c,Student s where c.cid=s.classes.cid").list(); 101 session.close(); 102 return cList; 103 } 104 105 /** 106 * 内连?? 107 * @return 108 */ 109 public List<Classes> queryClasses_Student_INNER(){ 110 Session session = sessionFactory.openSession(); 111 List<Classes> cList = session.createQuery("from Classes c inner join c.students").list(); 112 session.close(); 113 return cList; 114 } 115 116 /** 117 * 迫切内连?? 118 * @return 119 */ 120 public List<Classes> queryClasses_Student_INNER_FETCH(){ 121 Session session = sessionFactory.openSession(); 122 List<Classes> cList = session.createQuery("from Classes c inner join fetch c.students").list(); 123 session.close(); 124 return cList; 125 } 126 127 /** 128 * 左外连接 129 */ 130 public List<Classes> queryClasses_Student_LeftJoin(){ 131 Session session = sessionFactory.openSession(); 132 List<Classes> cList = session.createQuery("from Classes c left outer join c.students").list(); 133 session.close(); 134 return cList; 135 } 136 137 /** 138 * 迫切左外连接 139 */ 140 public List<Classes> queryClasses_Student_LeftJoin_fetch(){ 141 Session session = sessionFactory.openSession(); 142 String hql = "from Classes c left outer join fetch c.students"; 143 hql = "from Student s left outer join fetch s.classes c"; 144 List<Classes> cList = session.createQuery(hql).list(); 145 session.close(); 146 return cList; 147 } 148 149 /** 150 * 带select的查?? 151 */ 152 public List<Classes> queryClasses_Student_Select(){ 153 Session session = sessionFactory.openSession(); 154 String hql = "select new cn.itcast.hiberate.sh.domain.ClassesView(c.cname,s.sname) " + 155 "from Student s left outer join s.classes c"; 156 List<Classes> cList = session.createQuery(hql).list(); 157 session.close(); 158 return cList; 159 } 160 161 /** 162 * 多对?? 163 */ 164 public void testQueryCourse_Student(){ 165 Session session = sessionFactory.openSession(); 166 List<Student> studentList = session.createQuery("from Student s inner join fetch s.courses c").list(); 167 session.close(); 168 } 169 170 171 /** 172 * ????多结合多对多 173 */ 174 public List<Student> queryClasses_Student_Course(){ 175 Session session = sessionFactory.openSession(); 176 String hql = "from Classes cs inner join fetch cs.students s inner join fetch s.courses c"; 177 hql = "from Student s inner join fetch s.classes cs inner join fetch s.courses c"; 178 //hql = "from Classes cs left outer join fetch cs.students s left outer join fetch s.courses c"; 179 List<Student> cList = session.createQuery(hql).list(); 180 // Set<Classes> cset = new HashSet<Classes>(cList); 181 // cList = new ArrayList<Classes>(cset); 182 System.out.println(cList.size()); 183 // for(Classes classes:cList){ 184 // System.out.println(classes.getCid()); 185 // Set<Student> students = classes.getStudents(); 186 // for(Student student:students){ 187 // System.out.println(student.getSname()); 188 // Set<Course> courses = student.getCourses(); 189 // for(Course course:courses){ 190 // System.out.println(course.getCname()); 191 // } 192 // } 193 // } 194 session.close(); 195 return cList; 196 } 197 }
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