andriod increase, delete, change, check

Change the database additions and deletions into a single package

1*/2 Package Com.itheima28.sqlitedemo.dao;3 import java.util.ArrayList;4 import java.util.List;5 6 import Android.content.Context;7 import android.database.Cursor;8 import android.database.sqlite.SQLiteDatabase;9 Ten import Com.itheima28.sqlitedemo.dao.entities.Person; One import Com.itheima28.sqlitedemo.db.PersonSQliteOpenHelper; Apublic class Persondao {//who calls my package for this operation, just pass in my own object -Private Personsqliteopenhelper Mopenhelper; //the Help class object for the database -  the Public Persondao (context context) { -Mopenhelper =new Personsqliteopenhelper (context); -}

1 //Insert Operation2  Public voidInsert (person person) {3 //first connect the database this operation class Persondao has done, with its object Mopenhelper under the method4Sqlitedatabase db =mopenhelper.getwritabledatabase ();5 //determine if the database is open6 if(Db.isopen ()) {//If the database is open, perform the added action7 //perform actions added to the database//What is the object coming in, what is it, and what is it written in front of it?8Db.execsql ("INSERT into person (name,age) values (?,?);",Newobject[]{person.getname (), Person.getage ()});9Db.close ();//Database ShutdownTen } One}

1 //delete data by ID2  Public voidDeleteintID) {3Sqlitedatabase db = Mopenhelper.getwritabledatabase ();//get a writable database object4 if(Db.isopen ()) {//If the database is open, perform the following actions//Pass in the ID directly. Integer is an object type and int is not. So no. 5Db.execsql ("Delete from person where _id=?;",NewInteger[]{id});//6 db.close ();7 }8}

1 //Update2  Public voidUpdata (intid,string name) {3Sqlitedatabase db = Mopenhelper.getwritabledatabase ();//get a writable database object4 if(Db.isopen ()) {5Db.execsql ("updata person set name =?") where _id =?; ",Newobject[]{name,id});6 }7 db.close ();8}

1 //Query All2  PublicList<person>Queryall () {3Sqlitedatabase db = Mopenhelper.getwritabledatabase ();//get read-only database objects4 if(Db.isopen ()) {5cursor cursor = db.rawquery ("select * from person;",NULL);//query to get "cursor result set"6 if(Cursor! =NULL&& Cursor.getcount () >0) {//query set greater than 07List<person> personlist =NewArraylist<person> ();//Create a collection personlist8  while(Cursor.movetonext ()) {//table cursor moves from top to bottom9 intID =cursor.getint (0);//take the No. 0 column---IDTenString name = cursor.getstring (1);//take the 1th column---name One intAge = Cursor.getint (2);//take the 2nd column--- age APersonlist.add (NewPerson (id,name,age));//load the acquired data into the collection Personlist - } - db.close (); the returnPersonlist;//return this collection - } - db.close (); - } + return NULL; -}

1 //query for one, such as ID2  PublicPerson Queryitem (intID) {//Person Type3Sqlitedatabase db = Mopenhelper.getwritabledatabase ();//get read-only database objects4 if(Db.isopen ()) {//because Rawquery (string, string[]) type, the int ID is typed as string by id+ ""5Cursor cursor= db.rawquery ("Select _id,name,age from the person where _id=?;",NewString[]{id+ ""} );6 if(Cursor! =NULL&& Cursor.movetofirst ()) {//Movetofirst first found7 int_id = cursor.getint (0);//Get ID8String name= cursor.getstring (1);//Get name9 intAge = Cursor.getint (2);//Get AgeTen db.close (); One return NewPerson (_id,name,age); A } - } - return NULL; the } -}

andriod increase, delete, change, check