Hibernate查詢重要筆記 - HQL總結 數據庫各種查詢寶典 大總結

1. 查詢整個映射對象所有字段 

//直接from查詢出來的是一個映射對象，即：查詢整個映射對象所有字段
        String hql = "from Users";
        Query query = session.createQuery(hql);

        List<Users> users = query.list();
        for(Users user : users){
            System.out.println(user.getName() + " : " + user.getPasswd() + " : " + user.getId());
        }

 輸出結果爲：
name1 : password1 : 1
name2 : password2 : 2
name3 : password3 : 3

2.查詢單個字段  

//查詢單個字段
        String hql = " select name from Users";
        Query query = session.createQuery(hql);

        List<String> list = query.list();
        for(String str : list){
            System.out.println(str);
        }
輸出結果爲：
name1
name2
name3

3.查詢其中幾個字段 
  

//查詢其中幾個字段
        String hql = " select name,passwd from Users";
        Query query = session.createQuery(hql);
        //默認查詢出來的list裏存放的是一個Object數組
        List<Object[]> list = query.list();
        for(Object[] object : list){
            String name = (String)object[0];
            String passwd = (String)object[1];

            System.out.println(name + " : " + passwd);
        }
輸出結果爲：
name1 : password1
name2 : password2
name3 : password3

4.修改默認查詢結果(query.list())不以Object[]數組形式返回，以List形式返回 

引用

//查詢其中幾個字段,添加new list(),注意list裏的l是小寫的。也不需要導入包，這樣通過query.list()出來的list裏存放的不再是默認的Object數組了，而是List集合了   
        String hql = " select new list(name,passwd) from Users";   
        Query query = session.createQuery(hql);   
        //默認查詢出來的list裏存放的是一個Object數組，但是在這裏list裏存放的不再是默認的Object數組了，而是List集合了   
        List<List> list = query.list();   
        for(List user : list){   
            String name = (String)user.get(0);   
            String passwd = (String)user.get(1);   
               
            System.out.println(name + " : " + passwd);   
        }   
        /**  
        輸出結果爲：  
         name1 : password1  
        name2 : password2  
        name3 : password3  
         */ 

5.修改默認查詢結果(query.list())不以Object[]數組形式返回，以Map形式返回 

//查詢其中幾個字段,添加new map(),注意map裏的m是小寫的。也不需要導入包，這樣通過query.list()出來的list裏存放的不再是默認的Object數組了，而是map集合了
        String hql = " select new map(name,passwd) from Users";
        Query query = session.createQuery(hql);
        //默認查詢出來的list裏存放的是一個Object數組，但是在這裏list裏存放的不再是默認的Object數組了，而是Map集合了
        List<Map> list = query.list();
        for(Map user : list){
            //一條記錄裏所有的字段值都是map裏的一個元素,key是字符串0,1,2,3....，value是字段值
            //如果將hql改爲：String hql = " select new map(name as username,passwd as password) from Users";,那麼key將不是字符串0,1,2...了，而是"username","password"了
            String name = (String)user.get("0");//get("0");是get(key),注意:0,1,2...是字符串，而不是整形
            String passwd = (String)user.get("1");

            System.out.println(name + " : " + passwd);
        }
        /**
        輸出結果爲：
         name1 : password1
        name2 : password2
        name3 : password3
         */

6.修改默認查詢結果(query.list())不以Object[]數組形式返回，以Set形式返回,但是因爲Set裏是不允許有重複的元素，所以:username和password的值不能相同。只需將hql改爲：String hql = " select new set(name,passwd) from Users"; 

7.修改默認查詢結果(query.list())不以Object[]數組形式返回，以自定義類型返回 

自定義類： 
  

package com.domain;

public class MyUser {

    private String username;
    private String password;
//因爲：String hql = " select new  com.domain.MyUser(name,passwd) from Users";所以必須要有接受2個參數的構造函數
    public MyUser(String username,String password){
        this.username = username;
        this.password = password;
    }

    public String getUsername() {
        return username;
    }
    public void setUsername(String username) {
        this.username = username;
    }
    public String getPassword() {
        return password;
    }
    public void setPassword(String password) {
        this.password = password;
    }


}

  

//通過query.list()出來的list裏存放的不再是默認的Object數組了,而是自定義的類MyUser,必須加包名，String hql = "from Users";中的Users類也是必須加包名的，但是因爲再Users.hbm.xml裏<hibernate-mapping auto-import="true"> auto-import默認值爲true（所以auto-import屬性也可以不寫）,自動導入了
        String hql = " select new  com.domain.MyUser(name,passwd) from Users";
        Query query = session.createQuery(hql);
        //默認查詢出來的list裏存放的是一個Object數組，但是在這裏list裏存放的不再是默認的Object數組了，而是MyUser對象了
        List<MyUser> myUsers = query.list();
        for(MyUser myUser : myUsers){
            String name = myUser.getUsername();
            String passwd = myUser.getPassword();
            System.out.println(name + " : " + passwd);
        }
        /**
        輸出結果爲：
        name1 : password1
        name2 : password2
        name3 : password3
         */

8：條件查詢 

//條件查詢，參數索引值從0開始，索引位置。通過setString,setParameter設置參數
        String hql = "from Users where name=? and passwd=?";
        Query query = session.createQuery(hql);
        //第1種方式
//      query.setString(0, "name1");
//      query.setString(1, "password1");
        //第2種方式
        query.setParameter(0, "name1",Hibernate.STRING);
        query.setParameter(1, "password1",Hibernate.STRING);
        List<Users> list = query.list();
        for(Users users : list){
            System.out.println(users.getId());
        }

          

//條件查詢，自定義索引名(參數名):username,:password.通過setString,setParameter設置參數
        String hql = "from Users where name=:username and passwd=:password";
        Query query = session.createQuery(hql);
        //第1種方式
//      query.setString("username", "name1");
//      query.setString("password", "password1");
        //第2種方式,第3個參數確定類型
        query.setParameter("username", "name1",Hibernate.STRING);
        query.setParameter("password", "password1",Hibernate.STRING);
        List<Users> list = query.list();
        for(Users users : list){
            System.out.println(users.getId());
        }

//條件查詢,通過setProperties設置參數
        String hql = "from Users where name=:username and passwd=:password";
        Query query = session.createQuery(hql);
        //MyUser類的2個屬性必須和:username和:password對應
        MyUser myUser = new MyUser("name1","password1");
        query.setProperties(myUser);
        List<Users> list = query.list();
        for(Users users : list){
            System.out.println(users.getId());
        }

package com.hp.ts.bca.user.bo;

import com.hp.ts.bca.common.BaseObject;

public class StationUser  extends BaseObject {
    private static final long serialVersionUID = -1175811459644997844L;
    private int id;
    private String username;
    private String officePhone;
    private String mobilePhone1;
    private String officeEmail;
    private Integer ifDefault;
    public StationUser(int id, String username, String officePhone,
            String mobilePhone1, String officeEmail, Integer ifDefault) {
        super();
        this.id = id;
        this.username = username;
        this.officePhone = officePhone;
        this.mobilePhone1 = mobilePhone1;
        this.officeEmail = officeEmail;
        this.ifDefault = ifDefault;
    }
    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    public String getUsername() {
        return username;
    }
    public void setUsername(String username) {
        this.username = username;
    }
    public String getOfficePhone() {
        return officePhone;
    }
    public void setOfficePhone(String officePhone) {
        this.officePhone = officePhone;
    }
    public String getMobilePhone1() {
        return mobilePhone1;
    }
    public void setMobilePhone1(String mobilePhone1) {
        this.mobilePhone1 = mobilePhone1;
    }
    public String getOfficeEmail() {
        return officeEmail;
    }
    public void setOfficeEmail(String officeEmail) {
        this.officeEmail = officeEmail;
    }
    public Integer getIfDefault() {
        return ifDefault;
    }
    public void setIfDefault(Integer ifDefault) {
        if(ifDefault==null)
            ifDefault=0;
        else
            this.ifDefault = ifDefault;
    }
    @Override
    public int hashCode() {
        final int prime = 31;
        int result = 1;
        result = prime * result + id;
        result = prime * result
                + ((ifDefault == null) ? 0 : ifDefault.hashCode());
        result = prime * result
                + ((mobilePhone1 == null) ? 0 : mobilePhone1.hashCode());
        result = prime * result
                + ((officeEmail == null) ? 0 : officeEmail.hashCode());
        result = prime * result
                + ((officePhone == null) ? 0 : officePhone.hashCode());
        result = prime * result
                + ((username == null) ? 0 : username.hashCode());
        return result;
    }
    @Override
    public boolean equals(Object obj) {
        if (this == obj)
            return true;
        if (obj == null)
            return false;
        if (getClass() != obj.getClass())
            return false;
        StationUser other = (StationUser) obj;
        if (id != other.id)
            return false;
        if (ifDefault == null) {
            if (other.ifDefault != null)
                return false;
        } else if (!ifDefault.equals(other.ifDefault))
            return false;
        if (mobilePhone1 == null) {
            if (other.mobilePhone1 != null)
                return false;
        } else if (!mobilePhone1.equals(other.mobilePhone1))
            return false;
        if (officeEmail == null) {
            if (other.officeEmail != null)
                return false;
        } else if (!officeEmail.equals(other.officeEmail))
            return false;
        if (officePhone == null) {
            if (other.officePhone != null)
                return false;
        } else if (!officePhone.equals(other.officePhone))
            return false;
        if (username == null) {
            if (other.username != null)
                return false;
        } else if (!username.equals(other.username))
            return false;
        return true;
    }
    @Override
    public String toString() {
        return "StationUser [id=" + id + ", username=" + username
                + ", officePhone=" + officePhone + ", mobilePhone1="
                + mobilePhone1 + ", officeEmail=" + officeEmail
                + ", ifDefault=" + ifDefault + "]";
    }





}

@Override
    public PageResponse<User> getUserListByStationId(int currentPage,
            int rowsPerPage, String sidx, String sord, Integer stationId) {
        StringBuilder hql = new StringBuilder();
        hql.append("select new com.hp.ts.bca.user.bo.StationUser(a.id,a.username,a.officePhone,a.mobilePhone1,a.officeEmail,ug.ifDefault) FROM User a, UserGroup ug WHERE a.id=ug.userId and ug.groupId=");
        hql.append(stationId);
        //hql.append("FROM User AS user, UserGroup AS ug WHERE user.id=ug.userId");
        PageResponse<User> userList = this.groupDao.excutePage(hql.toString(),
                currentPage, rowsPerPage, sidx, sord);
        return userList;