Hibernate 原生SQL
hibernate 原生sql
如果你想使用數據庫特定的功能如查詢提示或 oracle 中的 connect 關鍵字的話，你可以使用原生 sql 數據庫來表達查詢。
hibernate 3.x 允許您為所有的創建，更新，刪除，和加載操作指定手寫 sql ，包括存儲過程。
您的應用程序會在會話界面用 createsqlquery() 方法創建一個原生 sql 查詢：
public sqlquery createsqlquery(string sqlstring) throws hibernateexception
當你通過一個包含 sql 查詢的 createsqlquery() 方法的字符串時，你可以將 sql 的結果與現有的 hibernate 實體，一個連接，或一個標量結果分別使用 addentity(), addjoin(), 和 addscalar() 方法進行關聯。
標量查詢
最基本的 sql 查詢是從一個或多個列表中獲取一個標量（值）列表。以下是使用原生 sql 進行獲取標量的值的語法：
string sql = "select first_name, salary from employee"; sqlquery query = session.createsqlquery(sql); query.setresulttransformer(criteria.alias_to_entity_map); list results = query.list();
實體查詢
以上的查詢都是關于返回標量值的查詢，只是基礎性地返回結果集中的“原始”值。以下是從原生 sql 查詢中通過 addentity() 方法獲取實體對象整體的語法：
string sql = "select * from employee"; sqlquery query = session.createsqlquery(sql); query.addentity(employee.class); list results = query.list();
指定 sql 查詢
以下是從原生 sql 查詢中通過 addentity() 方法和使用指定 sql 查詢來獲取實體對象整體的語法：
string sql = "select * from employee where id = :employee_id";
sqlquery query = session.createsqlquery(sql);
query.addentity(employee.class);
query.setparameter("employee_id", 10);
list results = query.list();
原生 sql 的例子
考慮下面的 pojo 類：
public class employee {
private int id;
private string firstname;
private string lastname;
private int salary;
public employee() {}
public employee(string fname, string lname, int salary) {
this.firstname = fname;
this.lastname = lname;
this.salary = salary;
}
public int getid() {
return id;
}
public void setid( int id ) {
this.id = id;
}
public string getfirstname() {
return firstname;
}
public void setfirstname( string first_name ) {
this.firstname = first_name;
}
public string getlastname() {
return lastname;
}
public void setlastname( string last_name ) {
this.lastname = last_name;
}
public int getsalary() {
return salary;
}
public void setsalary( int salary ) {
this.salary = salary;
}
}
讓我們創建以下 employee 表來存儲 employee 對象：
create table employee ( id int not null auto_increment, first_name varchar(20) default null, last_name varchar(20) default null, salary int default null, primary key (id) );
以下是映射文件：
<?xml version="1.0" encoding="utf-8"?>
<!doctype hibernate-mapping public
"-//hibernate/hibernate mapping dtd//en"
"http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
<class name="employee" table="employee">
<meta attribute="class-description">
this class contains the employee detail.
</meta>
<id name="id" type="int" column="id">
<generator class="native"/>
</id>
<property name="firstname" column="first_name" type="string"/>
<property name="lastname" column="last_name" type="string"/>
<property name="salary" column="salary" type="int"/>
</class>
</hibernate-mapping>
最后，我們將用 main() 方法創建應用程序類來運行應用程序，我們將使用原生 sql 查詢：
import java.util.*;
import org.hibernate.hibernateexception;
import org.hibernate.session;
import org.hibernate.transaction;
import org.hibernate.sessionfactory;
import org.hibernate.sqlquery;
import org.hibernate.criteria;
import org.hibernate.hibernate;
import org.hibernate.cfg.configuration;
public class manageemployee {
private static sessionfactory factory;
public static void main(string[] args) {
try{
factory = new configuration().configure().buildsessionfactory();
}catch (throwable ex) {
system.err.println("failed to create sessionfactory object." + ex);
throw new exceptionininitializererror(ex);
}
manageemployee me = new manageemployee();
/* add few employee records in database */
integer empid1 = me.addemployee("zara", "ali", 2000);
integer empid2 = me.addemployee("daisy", "das", 5000);
integer empid3 = me.addemployee("john", "paul", 5000);
integer empid4 = me.addemployee("mohd", "yasee", 3000);
/* list down employees and their salary using scalar query */
me.listemployeesscalar();
/* list down complete employees information using entity query */
me.listemployeesentity();
}
/* method to create an employee in the database */
public integer addemployee(string fname, string lname, int salary){
session session = factory.opensession();
transaction tx = null;
integer employeeid = null;
try{
tx = session.begintransaction();
employee employee = new employee(fname, lname, salary);
employeeid = (integer) session.save(employee);
tx.commit();
}catch (hibernateexception e) {
if (tx!=null) tx.rollback();
e.printstacktrace();
}finally {
session.close();
}
return employeeid;
}
/* method to read all the employees using scalar query */
public void listemployeesscalar( ){
session session = factory.opensession();
transaction tx = null;
try{
tx = session.begintransaction();
string sql = "select first_name, salary from employee";
sqlquery query = session.createsqlquery(sql);
query.setresulttransformer(criteria.alias_to_entity_map);
list data = query.list();
for(object object : data)
{
map row = (map)object;
system.out.print("first name: " + row.get("first_name"));
system.out.println(", salary: " + row.get("salary"));
}
tx.commit();
}catch (hibernateexception e) {
if (tx!=null) tx.rollback();
e.printstacktrace();
}finally {
session.close();
}
}
/* method to read all the employees using entity query */
public void listemployeesentity( ){
session session = factory.opensession();
transaction tx = null;
try{
tx = session.begintransaction();
string sql = "select * from employee";
sqlquery query = session.createsqlquery(sql);
query.addentity(employee.class);
list employees = query.list();
for (iterator iterator =
employees.iterator(); iterator.hasnext();){
employee employee = (employee) iterator.next();
system.out.print("first name: " + employee.getfirstname());
system.out.print(" last name: " + employee.getlastname());
system.out.println(" salary: " + employee.getsalary());
}
tx.commit();
}catch (hibernateexception e) {
if (tx!=null) tx.rollback();
e.printstacktrace();
}finally {
session.close();
}
}
}
編譯和執行
這是編譯并運行上述應用程序的步驟。確保你有適當的 path 和 classpath，然后執行編譯程序。
- 按照在配置一章講述的方法創建
hibernate.cfg.xml配置文件。 - 如上述所示創建
employee.hbm.xml映射文件。 - 如上述所示創建
employee.java源文件并編譯。 - 如上述所示創建
manageemployee.java源文件并編譯。 - 執行 manageemployee 二進制代碼運行程序。
你會得到下面的結果，并且記錄將會在 employee 表創建。
$java manageemployee .......various log messages will display here........ first name: zara, salary: 2000 first name: daisy, salary: 5000 first name: john, salary: 5000 first name: mohd, salary: 3000 first name: zara last name: ali salary: 2000 first name: daisy last name: das salary: 5000 first name: john last name: paul salary: 5000 first name: mohd last name: yasee salary: 3000
如果你檢查你的 employee 表，它應該有以下記錄：
mysql> select * from employee; +----+------------+-----------+--------+ | id | first_name | last_name | salary | +----+------------+-----------+--------+ | 26 | zara | ali | 2000 | | 27 | daisy | das | 5000 | | 28 | john | paul | 5000 | | 29 | mohd | yasee | 3000 | +----+------------+-----------+--------+ 4 rows in set (0.00 sec) mysql>
Java實戰