| Criteria API, Subqueries, In Expressions |
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http://stackoverflow.com/questions/4483576/jpa-2-0-criteria-api-subqueries-in-expressions |
CriteriaBuilder criteriaBuilder = entityManager.getCriteriaBuilder();
CriteriaQuery<Object> criteriaQuery = criteriaBuilder.createQuery();
Root<EMPLOYEE> from = criteriaQuery.from(EMPLOYEE.class);
Path<Object> path = from.get("compare_field"); // field to map with sub-query
from.fetch("name");
from.fetch("id");
CriteriaQuery<Object> select = criteriaQuery.select(from);
Subquery<PROJECT> subquery = criteriaQuery.subquery(PROJECT.class);
Root fromProject = subquery.from(PROJECT.class);
subquery.select(fromProject.get("requiredColumnName")); // field to map with main-query
subquery.where(criteriaBuilder.equal("name",name_value));
subquery.where(criteriaBuilder.equal("id",id_value));
select.where(criteriaBuilder.in(path).value(subquery));
TypedQuery<Object> typedQuery = entityManager.createQuery(select);
List<Object> resultList = typedQuery.getResultList();
====================================================
CriteriaBuilder cb = em.getCriteriaBuilder();
CriteriaQuery<Employee> c = cb.createQuery(Employee.class);
Root<Employee> emp = c.from(Employee.class);
Subquery<Integer> sq = c.subquery(Integer.class);
Root<Project> project = sq.from(Project.class);
Join<Project, Employee> sqEmp = project.join(Project_.employees);
sq.select(sqEmp.get(Employee_.id)).where(
cb.equal(project.get(Project_.name),
cb.parameter(String.class, "project")));
c.select(emp).where(
cb.in(emp.get(Employee_.id)).value(sq));
TypedQuery<Employee> q = em.createQuery(c);
q.setParameter("project", projectName); // projectName is a String
List<Employee> employeess = q.getResultList();
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| oracle 分页 |
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http://www.cnblogs.com/hxw/archive/2005/09/11/234619.html |
1.根据ROWID来分
select * from t_xiaoxi where rowid in(select rid from (select rownum rn,rid from(select rowid rid,cid from
t_xiaoxi order by cid desc) where rownum<10000) where rn>9980) order by cid desc;
执行时间0.03秒
2.按分析函数来分
select * from (select t.*,row_number() over(order by cid desc) rk from t_xiaoxi t) where rk<10000 and rk>9980;
执行时间1.01秒
3.按ROWNUM来分
select * from(select t.*,rownum rn from(select * from t_xiaoxi order by cid desc) t where rownum<10000) where
rn>9980;执行时间0.1秒
其中t_xiaoxi为表名称，cid为表的关键字段，取按CID降序排序后的第9981-9999条记录，t_xiaoxi表有70000多条记录
个人感觉1的效率最好，3次之，2最差
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| 为了有利于保护安全性，IE已限制此网页运行可以访问计算机的脚本或 ActiveX 控件 |
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http://blog.sina.com.cn/s/blog_6f6b4c3c0100r673.html |
1. 如果你的HTML文件中有下面这句话
<html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns="http://www.w3.org/TR/REC-html40">
那直接加入下面这句话就行了
<!-- saved from url=(0031)http://blog.sina.com.cn/seeweb/ -->
2. 没有的话.用下面这两句，记住要放在<head>的前面 (url=(0031) 0031是十六进制数,表示后面的域名的字符数)
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<!-- saved from url=(0031)http://blog.sina.com.cn/seeweb/ -->
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