以下是本人对Hibernate使用原生SQL语句的理解:
在项目开发当中使用Hibernate提供的HQL有时候不能满足需求,尤其是多表查询或者是多表中没创建主外键关联关系,我也试过平常的连接
比如说a表和b表,a、b表没建立主外键关系。a、b表对应的实体为A、B (SQLServer语法)
create table a
(
aId int identity(1,1) not null,
aName varchar(10) not null
)
create table b
(
bId int identity(1,1) not null,
bName varchar(50) not null,
aId int not null
)
select a表字段,b表字段 from A as a,B as b where a.某字段=b.某字段
得出的数据完全不是我想要的数据,使用Left join又报错,在网上找了很多 有人说a、b表没建立主外键所以在Hibernate中不能用left join
,Hibernate没有on关键字。
最后没办法,就想到了用Hibernate的原生SQL语句。
单表Hibernate原生SQL语句
select {a.*} from a as a;
解释:{a.*}表示返回a表中所有的列 并且返回Object[]数组,数组里包含1个对象
多表Hibernate原生SQL语句
select {a.*},{b.*} from a as a left join b as b on a.aId=b.aId;
解释:{a.*},{b.*}返回a表和b表中所有的字段,它返回Object[]数组,数组里包含2个对象 依此类推。
返回多列的Hibernate原生SQL语句
select a.aName,b.bName from a as a left join b as b on a.aId=b.aId;
在网上很多人认为Hibernate原生SQL语句不能返回多列 我就在想开发Hibernate不可能想不到吧!! 假如多张表的字段加起来有100多个字段
,但是只要取的只有10多个字段,那这么办呢?
所以我就研究,最后如我所愿,可以返回多字段,一下就是我写的返回多表和多字段的方法:
//返回2张表中所有的数据
public List getInvoDetailForTaxpayerInfo(final MemberActRecord memberActRecord)
{
return (List) getHibernateTemplate().execute(new HibernateCallback()
{
public Object doInHibernate(Session session)
{
String sql = "select {invo.*},{ty.*} from member_act_record invo left join mh_order ty on invo.order_id=ty.id ";
//筛选查询条件
if(memberActRecord!=null&&StringUtils.isNotBlank(memberActRecord.getClueOwnerCode())) {
sql+=" and invo.clue_owner_code="+memberActRecord.getClueOwnerCode();
}
if(memberActRecord!=null&&StringUtils.isNotBlank(memberActRecord.getClueOwnerPhone())) {
sql+=" and invo.clue_owner_phone="+memberActRecord.getClueOwnerPhone();
}
if(memberActRecord!=null&&StringUtils.isNotBlank(memberActRecord.getPhone())) {
sql+=" and invo.phone="+memberActRecord.getPhone();
}
if(memberActRecord!=null&&memberActRecord.getOrderId()>0) {
sql+=" and invo.order_id="+memberActRecord.getOrderId();
}
if(memberActRecord!=null&&StringUtils.isNotBlank(memberActRecord.getStatus())) {
sql+=" and invo.status="+memberActRecord.getStatus();
}
if(memberActRecord!=null&&StringUtils.isNotBlank(memberActRecord.getStartDate())) {
sql+=" and invo.create_time>='"+memberActRecord.getStartDate()+" 00:00:00'";
}
if(memberActRecord!=null&&StringUtils.isNotBlank(memberActRecord.getEndDate())) {
sql+=" and invo.create_time<='"+memberActRecord.getEndDate()+" 23:59:59'";
}
if(memberActRecord!=null&&StringUtils.isNotBlank(memberActRecord.getOrderStatus())) {
sql+=" and ty.status="+memberActRecord.getOrderStatus();
}
sql+=" order by invo.create_time desc";
SQLQuery sQuery = session.createSQLQuery(sql);
sQuery.addEntity("invo", MemberActRecord.class).addEntity("ty", MhOrder.class);
//在Hibernate中页数和每页显示的记录数不能为负数
if(memberActRecord.getPage()>=0 && memberActRecord.getPageSize()>=0)
{
sQuery.setFirstResult(memberActRecord.getPage());
sQuery.setMaxResults(memberActRecord.getPageSize());
}
List list = sQuery.list();
if(list!=null && list.size()>0)
{
return list;
}
return null;
}
});
}
//返回多字段
public List getInvoDetailAndInvoDetailTotalMoney(final com.ketuoda.entity.Query query)
{
return (List) getHibernateTemplate().execute(new HibernateCallback()
{
public Object doInHibernate(Session session)
{
String sql = "select distinct(invo.InvoDetail_TaxEnrollID),ty.TaxpayerName,count(*) as cu,"+
"sum(invo.InvoDetail_TotalMoney) as tMoney from InvoDetail invo left join"+
" TaxpayerInfo ty on invo.InvoDetail_TaxEnrollID="+
"left(ty.TaxPayerCertID+'00000000000000000000',20) group by
invo.InvoDetail_TaxEnrollID,ty.TaxpayerName";
SQLQuery sQuery = session.createSQLQuery(sql);
sQuery.addScalar("InvoDetail_TaxEnrollID", Hibernate.STRING);
sQuery.addScalar("TaxpayerName", Hibernate.STRING);
sQuery.addScalar("cu", Hibernate.INTEGER);
sQuery.addScalar("tMoney", Hibernate.INTEGER);
List list = sQuery.list();
if(list!=null && list.size()>0)
{
return list;
}
return null;
}
});
}
返回2张表中所有的数据方法解释:
//session创建的是createSQLQuery而不是createQuery
SQLQuery sQuery = session.createSQLQuery(sql);
//addEntity("表的别名",Class)表示持久化的类 我这里是2个类 因为我返回的是2张表的数据
sQuery.addEntity("invo", InvoDetail.class).addEntity("ty", TaxpayerInfo.class);
返回多字段的数据方法解释:
SQLQuery sQuery = session.createSQLQuery(sql);
//addScalar("列名或者列的别名",Type) Hibernate.STRING表示这列返回的是string类型的,你想返回什么类型就什么类型目的在与你
sQuery.addScalar("InvoDetail_TaxEnrollID", Hibernate.STRING);
sQuery.addScalar("TaxpayerName", Hibernate.STRING);
sQuery.addScalar("cu", Hibernate.INTEGER);
sQuery.addScalar("tMoney", Hibernate.INTEGER);