Hibernate的hql查询语句详细总结
Hql即Hibernate Query Language,是一个面向对象的查询语言，是基于对象进行查询的，不是基于数据库中表，字段的。
1、准备
首先有两个类TBook类和Category类，两者之间是多对一的关系。
两个类对应两张表，我们先保存一些数据。
@Test
public void save() {
Session session = null;
Transaction tran = null;
try {
session = SessionUtil.getSession();
tran = session.beginTransaction();
Category c1 = new Category();
c1.setCategory("文学");
Category c2 = new Category();
c2.setCategory("历史");
Category c3 = new Category();
c3.setCategory("武侠");
Category c4 = new Category();
c4.setCategory("科幻");
Category c5 = new Category();
c5.setCategory("言情");
TBook book1 = new TBook();
book1.setBName("红楼梦");
book1.setAuthor("曹雪芹");
book1.setBPrice(60);
book1.setPubDate(new Date());
book1.setCategory(c1);
TBook book2 = new TBook();
book2.setBName("资治通鉴");
book2.setAuthor("司马光");
book2.setBPrice(63);
book2.setPubDate(new Date());
book2.setCategory(c2);
TBook book3 = new TBook();
book3.setBName("射雕英雄传");
book3.setAuthor("金庸");
book3.setBPrice(73);
book3.setPubDate(new Date());
book3.setCategory(c3);
TBook book4 = new TBook();
book4.setBName("百年孤独");
book4.setAuthor("马尔克斯");
book4.setBPrice(56);
book4.setPubDate(new Date());
book4.setCategory(c4);
TBook book5 = new TBook();
book5.setBName("傲慢与偏见");
book5.setAuthor("简奥斯丁");
book5.setBPrice(60);
book5.setPubDate(new Date());
book5.setCategory(c5);
TBook book6 = new TBook();
book6.setBName("西游记");
book6.setAuthor("罗贯中");
book6.setBPrice(68);
book6.setPubDate(new Date());
book6.setCategory(c1);
session.save(book1);
session.save(book2);
session.save(book3);
session.save(book4);
session.save(book5);
session.save(book6);
tran.commit();
} catch (Exception ex) {
ex.printStackTrace();
} finally {
session.close();
}
}表中详细数据
2、Hql查询
2.1、查询单一属性
@Test
public void query1(){
Session session = null;
try {
session = SessionUtil.getSession();
List list = session.createQuery("select BName from TBook").list();
for (String name : list) {
System.out.println(name);
}
} catch (Exception e) {
e.printStackTrace();
}finally{
SessionUtil.close(session);
}
} 红楼梦
资治通鉴
射雕英雄传
百年孤独
傲慢与偏见
西游记2.2、返回多个属性的查询
@Test
public void query2(){
Session session = null;
try {
session = SessionUtil.getSession();
List list = session.createQuery("select BName,BPrice from TBook")
.list();
for(Object[] book : list){
System.out.println("书名："+book[0]+"\t\t价格："+book[1]);
}
} catch (Exception e) {
e.printStackTrace();
}finally{
SessionUtil.close(session);
}
} 书名：红楼梦 价格：60
书名：资治通鉴 价格：63
书名：射雕英雄传 价格：73
书名：百年孤独 价格：56
书名：傲慢与偏见 价格：60
书名：西游记 价格：68注意查询多个属性的时候，查询到的是一个对象数据的集合。
另一种方式
@Test
public void query3(){
Session session = null;
try {
session = SessionUtil.getSession();
List list = session.createQuery("select new TBook(BName,BPrice) from TBook").list();
for(TBook book : list){
System.out.println(book.getBName()+"---"+book.getBPrice());
}
} catch (Exception e) {
e.printStackTrace();
}finally{
SessionUtil.close(session);
}
} 既然Hql中用到了new TBook(BName,BPrice)，那么你的pojo类中必然要有一个这样的构造函数。
2.3、查询全部属性
@Test
public void query3(){
Session session = null;
try {
session = SessionUtil.getSession();
List list = session.createQuery("from TBook").list();
for(TBook book : list){
System.out.println(book);
}
} catch (Exception e) {
e.printStackTrace();
}finally{
SessionUtil.close(session);
}
} TBook [id=1, author=曹雪芹, BName=红楼梦, BPrice=60, pubDate=2017-06-10 14:51:57.0]
TBook [id=2, author=司马光, BName=资治通鉴, BPrice=63, pubDate=2017-06-10 14:51:57.0]
TBook [id=3, author=金庸, BName=射雕英雄传, BPrice=73, pubDate=2017-06-10 14:51:57.0]
TBook [id=4, author=马尔克斯, BName=百年孤独, BPrice=56, pubDate=2017-06-10 14:51:57.0]
TBook [id=5, author=简奥斯丁, BName=傲慢与偏见, BPrice=60, pubDate=2017-06-10 14:51:57.0]
TBook [id=6, author=罗贯中, BName=西游记, BPrice=68, pubDate=2017-06-10 14:51:57.0]其中hql也可以写完整的，那样要使用别名，即select t from TBook t
2.4、条件查询之拼接查询语句
@Test
public void query4(){
Session session = null;
try {
session = SessionUtil.getSession();
List list = session.createQuery("from TBook where id<"+4).list();
for(TBook book : list){
System.out.println(book); }
} catch (Exception e) {
e.printStackTrace();
}finally{
SessionUtil.close(session);
}
} 2.5、条件查询之占位符方式
@Test
public void query5(){
Session session = null;
try {
session = SessionUtil.getSession();
List list = session.createQuery("from TBook where id)
.setInteger(0,3).list();
for(TBook book : list){
System.out.println(book);
}
} catch (Exception e) {
e.printStackTrace();
}finally{
SessionUtil.close(session);
}
} 注意下表从0开始
此后的查询结果不再罗列。
2.6、条件查询之基于别名的查询
@Test
public void query6(){
Session session = null;
try {
session = SessionUtil.getSession();
List list = session.createQuery("from TBook where id<:id")
.setParameter("id",4).list();
for(TBook book : list){
System.out.println(book);
}
} catch (Exception e) {
e.printStackTrace();
}finally{
SessionUtil.close(session);
}
} 2.7、分页查询
只需要设置起始位置和最大的查询数据个数即可，注意不包括设置的起始位置。
@Test
public void query7(){
Session session = null;
try {
session = SessionUtil.getSession();
List list = session.createQuery("from TBook")
.setFirstResult(0).setMaxResults(4).list();
for(TBook book : list){
System.out.println(book);
}
} catch (Exception e) {
e.printStackTrace();
}finally{
SessionUtil.close(session);
}
} 结果：
TBook [id=1, author=曹雪芹, BName=红楼梦, BPrice=60, pubDate=2017-06-10 14:51:57.0]
TBook [id=2, author=司马光, BName=资治通鉴, BPrice=63, pubDate=2017-06-10 14:51:57.0]
TBook [id=3, author=金庸, BName=射雕英雄传, BPrice=73, pubDate=2017-06-10 14:51:57.0]
TBook [id=4, author=马尔克斯, BName=百年孤独, BPrice=56, pubDate=2017-06-10 14:51:57.0]2.8、聚合查询之count
@Test
public void query8(){
Session session = null;
try {
session = SessionUtil.getSession();
//Object count = session.createQuery("select count(*) from TBook").uniqueResult();
Number count = (Number)session.createQuery("select count(*) from TBook").uniqueResult();
System.out.println(count.intValue());
} catch (Exception e) {
e.printStackTrace();
}finally{
SessionUtil.close(session);
}
}2.9、聚合查询之avg
@Test
public void query9(){
Session session = null;
try {
session = SessionUtil.getSession();
Number priceavg = (Number)session.createQuery("select avg(BPrice) from TBook").uniqueResult();
System.out.println(priceavg.doubleValue());
} catch (Exception e) {
e.printStackTrace();
}finally{
SessionUtil.close(session);
}
}2.10、排序查询
@Test
public void query10(){
Session session = null;
try {
session = SessionUtil.getSession();
List list = session.createQuery("from TBook order by BPrice").list();
for(TBook book : list){
System.out.println(book);
}
} catch (Exception e) {
e.printStackTrace();
}finally{
SessionUtil.close(session);
}
} 结果：
TBook [id=4, author=马尔克斯, BName=百年孤独, BPrice=56, pubDate=2017-06-10 14:51:57.0]
TBook [id=1, author=曹雪芹, BName=红楼梦, BPrice=60, pubDate=2017-06-10 14:51:57.0]
TBook [id=5, author=简奥斯丁, BName=傲慢与偏见, BPrice=60, pubDate=2017-06-10 14:51:57.0]
TBook [id=2, author=司马光, BName=资治通鉴, BPrice=63, pubDate=2017-06-10 14:51:57.0]
TBook [id=6, author=罗贯中, BName=西游记, BPrice=68, pubDate=2017-06-10 14:51:57.0]
TBook [id=3, author=金庸, BName=射雕英雄传, BPrice=73, pubDate=2017-06-10 14:51:57.0]2.11、分组查询
@Test
public void query11(){
Session session = null;
try {
session = SessionUtil.getSession();
List list = session.createQuery("select t.category.category,count(t.BName) from TBook t "
+ "group by t.category.category").list();
for (Object[] book : list) {
System.out.println(book[0]+"-----"+book[1]);
}
} catch (Exception e) {
e.printStackTrace();
}finally{
SessionUtil.close(session);
}
} 结果：
历史-----1
文学-----2
武侠-----1
科幻-----1
言情-----1