hibernate的基础学习--多表关联数据查询
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Hibernate共提供4种多表关联数据查询方式
OID数据查询+OGN数据查询方式
HQL数据查询方式
QBC数据查询方式
本地SQL查询方式(hibernate很少用)
1、OID数据查询+OGN数据查询方式
1 public class TestOID_OGN { 2 3 /** 4 * 什么时候时候什么时候发送 5 */ 6 @Test 7 public void findUser() { 8 SessionFactory sf = H3Util.getSessionFactory(); 9 Session session = sf.openSession(); 10 Transaction ts = session.beginTransaction(); 11 //小李子 12 User user = (User) session.get(User.class, "ff80808157c82de80157c82deb3c0001"); 13 System.out.println("========="); 14 15 System.out.println(user); 16 ts.commit(); 17 session.close(); 18 } 19 }
2、HQL数据查询方式
/** * HQL 数据查询 */ public class TestHQL { @Test public void findUser() { SessionFactory sf = H3Util.getSessionFactory(); Session session = sf.openSession(); Transaction ts = session.beginTransaction(); String hql = "from User"; Query query = session.createQuery(hql); @SuppressWarnings("unchecked") List<User> users = query.list(); for (User user : users) { System.out.println("=="+user); } ts.commit(); session.close(); } @Test public void findUser1() { SessionFactory sf = H3Util.getSessionFactory(); Session session = sf.openSession(); Transaction ts = session.beginTransaction(); //项目部中的所有 员工详细信息 String hql = "from Dept where deptname = ‘人事部‘"; Query query = session.createQuery(hql); Dept dept = (Dept) query.uniqueResult(); //OGN Set<User> list = dept.getUsers(); for (User user : list) { System.out.println(user); } ts.commit(); session.close(); } @Test public void findUser2() { SessionFactory sf = H3Util.getSessionFactory(); Session session = sf.openSession(); Transaction ts = session.beginTransaction(); //项目部中的所有 员工详细信息 //PO //Dept dept = (Dept) session.get(Dept.class,"ff80808157c831050157c83106c40001"); //DO Dept dept = new Dept(); dept.setDeptId("ff80808157c831050157c83106c40001"); //以对象作为条件查询：根据对象id //只要保证该对象具备：OID PO DO String hql = "from User where dept = ? "; Query query = session.createQuery(hql); query.setEntity(0, dept); //什么类型都可以只使用 //query.setParameter(0, dept); @SuppressWarnings("unchecked") List<User> list = (List<User>) query.list(); System.out.println("================="); for (User user : list) { System.out.println("=="+user); } ts.commit(); session.close(); } }
3、QBC数据查询方式
1 public class TestQBC { 2 3 @Test 4 public void findUser() { 5 SessionFactory sf = H3Util.getSessionFactory(); 6 Session session = sf.openSession(); 7 Transaction ts = session.beginTransaction(); 8 9 Criteria criteria = session.createCriteria(User.class); 10 criteria.add(Restrictions.eq("username", "小小")); 11 12 User user = (User) criteria.uniqueResult(); 13 //session.clear(); 14 System.out.println("========="); 15 System.out.println(user.getDept()); 16 17 ts.commit(); 18 session.close(); 19 } 20 21 @Test 22 public void findUser1() { 23 SessionFactory sf = H3Util.getSessionFactory(); 24 Session session = sf.openSession(); 25 Transaction ts = session.beginTransaction(); 26 27 Dept dept = new Dept(); 28 dept.setDeptId("ff80808157c831050157c83106c40001"); 29 30 Criteria criteria = session.createCriteria(User.class); 31 criteria.add(Restrictions.eq("dept", dept)); 32 33 @SuppressWarnings("unchecked") 34 List<User> list = criteria.list(); 35 System.out.println("=========分割线==========="); 36 for (User user : list) { 37 System.out.println(user); 38 } 39 40 ts.commit(); 41 session.close(); 42 } 43 44 @Test 45 public void findUser2() { 46 SessionFactory sf = H3Util.getSessionFactory(); 47 Session session = sf.openSession(); 48 Transaction ts = session.beginTransaction(); 49 50 Dept dept = (Dept) session.get(Dept.class, "ff80808157c831050157c83106c40001"); 51 52 //from User dept.deptId = ‘4028408157c14c210157c14c25370000‘ 53 Criteria criteria = session.createCriteria(User.class); 54 //使用OGN：OID 55 criteria.add(Restrictions.eq("dept.deptId", dept.getDeptId())); 56 57 58 System.out.println("==========分割线============"); 59 @SuppressWarnings("unchecked") 60 List<User> list = criteria.list(); 61 for (User user : list) { 62 System.out.println(user); 63 } 64 65 ts.commit(); 66 session.close(); 67 } 68 69 70 @Test 71 public void findUser3() { 72 SessionFactory sf = H3Util.getSessionFactory(); 73 Session session = sf.openSession(); 74 Transaction ts = session.beginTransaction(); 75 76 Dept dept = (Dept) session.get(Dept.class, "ff80808157c831050157c83106c40001"); 77 78 //from User dept.deptName = ‘项目部‘ 79 Criteria criteria = session.createCriteria(User.class); 80 //QBC:ONG方式中如果使用的的OID可以查询，但是如果使用的是除OID之外的其它属性 81 //就会报异常,解决方案：createAlias("dept") 82 //为dept起别名 83 criteria.createAlias("dept", "dept"); 84 criteria.add(Restrictions.eq("dept.deptName", dept.getDeptName())); 85 86 @SuppressWarnings("unchecked") 87 List<User> list = criteria.list(); 88 System.out.println("==========分割线==========="); 89 for (User user : list) { 90 System.out.println(user); 91 } 92 93 ts.commit(); 94 session.close(); 95 } 96 }
4、HQL数据查询方式（测试内连接，外连接查询）
1 /** 2 * @author nunu 3 * 测试内连接，外连接查询 4 */ 5 public class TestHQL2 { 6 7 8 /** 9 * 内连接： 10 * 有关联数据： 11 * 数据总量：从表被关联的数据总量 12 * 数据模型：主表数据(延迟从) + 从表数据(含主) 13 * 14 */ 15 @Test 16 public void findUser() { 17 SessionFactory sf = H3Util.getSessionFactory(); 18 Session session = sf.openSession(); 19 Transaction ts = session.beginTransaction(); 20 21 //部门：主表 22 //员工：从表 23 //sql：select d.*,u.* from t_dept d inner join t_user u on d.dept_id = u.dept_id; 24 String hql = "from Dept d inner join d.users"; 25 Query query = session.createQuery(hql); 26 27 @SuppressWarnings("unchecked") 28 List<Object[]> list = query.list(); 29 System.out.println(list.size()); 30 31 System.out.println("==========分割线==========="); 32 for (int i = 0; i < list.size(); i++) { 33 Object[] objs = list.get(i); 34 //主表数据 35 Dept dept = (Dept) objs[0]; 36 User user = (User) objs[1]; 37 System.out.println(user); 38 System.out.println(dept); 39 /* 40 //主表关联数据 41 Set<User> userSet = dept.getUsers(); 42 for (User user : userSet) { 43 //如果延迟加载:回发送新语句查询 44 System.out.println(user); 45 } 46 */ 47 System.out.println("=="); 48 /* 49 //从表数据 50 User user = (User) objs[1]; 51 52 //从表关联数据 53 Dept dept = user.getDept(); 54 55 System.out.println(dept); 56 */ 57 } 58 59 ts.commit(); 60 session.close(); 61 } 62 63 64 /** 65 * 迫切内连接(数据重复DISTINCT) 66 * 数据总量：从表被关联的数据总量 67 * 数据模型：主表数据 (含从) 68 */ 69 @Test 70 public void findUser1() { 71 SessionFactory sf = H3Util.getSessionFactory(); 72 Session session = sf.openSession(); 73 Transaction ts = session.beginTransaction(); 74 75 //部门：主表 76 //员工：从表 77 //sql：select d.*,u.* from t_dept d inner join t_user u on d.dept_id = u.dept_id; 78 String hql = "from Dept d inner join fetch d.users"; 79 Query query = session.createQuery(hql); 80 @SuppressWarnings("unchecked") 81 List<Dept> list = query.list(); 82 System.out.println(list.size()); 83 System.out.println("===============分隔符================="); 84 session.clear(); 85 for (Dept dept : list) { 86 Set<User> users = dept.getUsers(); 87 for (User user : users) { 88 System.out.println(user); 89 } 90 System.out.println("---------"); 91 } 92 93 ts.commit(); 94 session.close(); 95 } 96 97 98 /** 99 * 隐式内连接 100 * 数据总量：主表数据总量 101 * 数据模型：主表数据(延迟从) 102 */ 103 @Test 104 public void findUser2() { 105 SessionFactory sf = H3Util.getSessionFactory(); 106 Session session = sf.openSession(); 107 Transaction ts = session.beginTransaction(); 108 109 //部门：主表 110 //员工：从表 111 //sql：select d.*,u.* from t_dept d inner join t_user u on d.dept_id = u.dept_id; 112 String hql = "from Dept"; //默认就会用户关联了 113 Query query = session.createQuery(hql); 114 @SuppressWarnings("unchecked") 115 List<Dept> list = query.list(); 116 System.out.println(list.size()); 117 //session.clear(); 118 System.out.println("===============分隔符================="); 119 for (Dept dept : list) { 120 Set<User> users = dept.getUsers(); 121 for (User user : users) { 122 System.out.println(user); 123 } 124 System.out.println("-----------------"); 125 } 126 127 ts.commit(); 128 session.close(); 129 } 130 131 132 /** 133 左外连接: 以左侧表为准 134 数据总量：从表被关联数据总量+主表未关联数据总量 135 数据模型：主表数据(延迟从) ，从表数据 (含主) 136 (主表不存在关联数据的从表数据为0) 137 */ 138 @Test 139 public void findUser3() { 140 SessionFactory sf = H3Util.getSessionFactory(); 141 Session session = sf.openSession(); 142 Transaction ts = session.beginTransaction(); 143 144 //部门：主表 145 //员工：从表 146 //sql：select d.*,u.* from t_dept d inner join t_user u on d.dept_id = u.dept_id; 147 String hql = "from Dept d left outer join d.users";//默认就会用户关联了 148 Query query = session.createQuery(hql); 149 150 @SuppressWarnings("unchecked") 151 List<Object[]> list = query.list(); 152 System.out.println(list.size()); 153 154 System.out.println("============分隔符=============="); 155 for (int i = 0; i < list.size(); i++) { 156 Object[] objs = list.get(i); 157 //主表数据 158 System.out.println("\t ==主表数据"); 159 Dept dept = (Dept) objs[0]; 160 System.out.println("\t "+dept); 161 162 System.out.println("\t ==主表关联数据"); 163 //主表关联数据 164 Set<User> userSet = dept.getUsers(); 165 for (User user : userSet) { 166 //如果延迟加载:回发送新语句查询 167 System.out.println("\t "+user); 168 } 169 170 System.out.println("\t ==从表数据"); 171 //从表数据 172 User user = (User) objs[1]; 173 System.out.println("\t "+user); 174 175 System.out.println("\t ==从表关联数据"); 176 //从表关联数据 177 Dept dept1 = user.getDept(); 178 179 System.out.println("\t "+dept1); 180 System.out.println("-------------"); 181 } 182 ts.commit(); 183 session.close(); 184 } 185 186 187 /** 188 * 迫切左外连接(数据重复DISTINCT) 189 数据总量：从表被关联数据总量+主表未关联数据总量 190 数据模型：主表数据(含从) 191 (主表不存在关联数据的从表数据为0) 192 */ 193 @Test 194 public void findUser4() { 195 SessionFactory sf = H3Util.getSessionFactory(); 196 Session session = sf.openSession(); 197 Transaction ts = session.beginTransaction(); 198 199 //部门：主表 200 //员工：从表 201 //sql：select d.*,u.* from t_dept d inner join t_user u on d.dept_id = u.dept_id; 202 String hql = "from Dept d left outer join fetch d.users";//默认就会用户关联了 203 Query query = session.createQuery(hql); 204 205 @SuppressWarnings("unchecked") 206 List<Dept> list = query.list(); 207 System.out.println("============分隔符=============="); 208 for (Dept dept : list) { 209 System.out.println(dept); 210 211 Set<User> userSet = dept.getUsers(); 212 for (User user : userSet) { 213 System.out.println(user); 214 } 215 System.out.println("-----------"); 216 } 217 ts.commit(); 218 session.close(); 219 } 220 221 222 223 /** 224 * 右外连接: 225 数据总量：从表数据总量 226 数据模型：主表数据(延迟从) ，从表数据(含主) 227 (从表不存在关联数据的主表数据为null) 228 */ 229 @Test 230 public void findUser5() { 231 SessionFactory sf = H3Util.getSessionFactory(); 232 Session session = sf.openSession(); 233 Transaction ts = session.beginTransaction(); 234 235 //部门：主表 236 //员工：从表 237 //sql：select d.*,u.* from t_dept d inner join t_user u on d.dept_id = u.dept_id; 238 String hql = "from Dept d right outer join d.users";//默认就会用户关联了 239 Query query = session.createQuery(hql); 240 241 @SuppressWarnings("unchecked") 242 List<Object[]> list = query.list(); 243 System.out.println(list.size()); 244 System.out.println("=============分隔符================="); 245 for (int i = 0; i < list.size(); i++) { 246 Object[] objs = list.get(i); 247 //主表数据 248 //Dept dept = (Dept) objs[0]; 249 //System.out.println(dept.getDeptName()); 250 251 252 //主表关联数据 253 /*Set<User> userSet = dept.getUsers(); 254 for (User user : userSet) { 255 //如果延迟加载:回发送新语句查询 256 System.out.println(user.getUserId()); 257 }*/ 258 259 //从表数据 260 User user = (User) objs[1]; 261 System.out.println(user); 262 263 //从表关联数据 264 // Dept dept = user.getDept(); 265 // System.out.println(dept.getDeptName()); 266 // System.out.println(user.getUsername()); 267 System.out.println("-------------"); 268 } 269 ts.commit(); 270 session.close(); 271 ts.commit(); 272 session.close(); 273 } 274 275 276 }
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