SQLite use (Create, raise, increase, delete, change, check)

First database databases are created

1. Create a database package, create a mydatabasehelper in the package to inherit the Databasehelper class, and implement the method inside!

3 ImportAndroid.content.Context;4 Importandroid.database.sqlite.SQLiteDatabase;5 ImportAndroid.database.sqlite.SQLiteOpenHelper;6 ImportAndroid.widget.Toast;7 8 /**9 * Database Helper classTen * Created by Administrator on 2017/12/6. One  */ A  -  Public classMydatabasehelperextendssqliteopenhelper{ -  the      Public Static FinalString create_userinfo= "CREATE TABLE USERINFO ("//to create a table's SQL statement -+ "ID integer primary key autoincrement,"//ID Set Primary key -+ "username text,"//User name -+ "Age Integer,"//Age ++ "Sex text,"//Sex -+ "mautograph text)";//Signature +     PrivateContext Mcontext;  A  at  -     /** - * Constructed method of generation -      * @paramContext Get contexts -      * @paramname -      * @paramFactory in      * @paramversion -      */ to      PublicMydatabasehelper (context context, String name, Sqlitedatabase.cursorfactory factory,intversion) { +         Super(context, name, Factory, version); -Mcontext=context;//Get Context the     } *  $ Panax Notoginseng     /** - * Implementation Method the * CREATE DATABASE +      * @paramDB A      */ the @Override +      Public voidonCreate (Sqlitedatabase db) { -Db.execsql (Create_userinfo);//create a database with parameters as a statement of creation $Toast.maketext (Mcontext, "CREATE table succeeded", Toast.length_long). Show (); $     } -  -     /** the * Implementation Method - * Upgrade DatabaseWuyi      * @paramSqlitedatabase the      * @paramI -      * @paramI1 Wu      */ - @Override About      Public voidOnupgrade (Sqlitedatabase sqlitedatabase,intIintI1) { $  　　　　  -     } -}

2. Upgrade the database,

1 /**2 * Implementation Method3 * Upgrade Database4      * @paramSqlitedatabase5      * @paramI6      * @paramI17      */8 @Override9      Public voidOnupgrade (Sqlitedatabase sqlitedatabase,intIintI1) {TenSqlitedatabase.execsql ("drop table if exists create_userinfo");//Deleting a database OneSqlitedatabase.execsql ("drop table if exists create_contact");//Deleting a database A     } -  -  PrivateMydatabasehelper Mdbhelper;//declaring a database helper class variable the @Override -     protected voidonCreate (Bundle savedinstancestate) { -         Super. OnCreate (savedinstancestate); - Setcontentview (r.layout.activity_main); +Mdbhelper=NewMydatabasehelper ( This, "This,userinfo",NULL, 3); //3 represents an upgrade  -     } -     /** - * CREATE database at startup -      */ - @Override in     protected voidOnStart () { -         Super. OnStart (); toMdbhelper.getwritabledatabase ();//get a writable database, create a helper database +}

3. Querying the Database

1 @Override2      PublicList<userinfo>GetUserInfo (Mydatabasehelper db) {3Sqlitedatabase sqlhelper=db.getwritabledatabase ();4Cursor cursor=sqlhelper.query ("USERINFO",NULL,NULL,NULL,NULL,NULL,NULL);5 UserInfo user;6List<userinfo> list=NewArraylist<>();7         if(Cursor.movetofirst ()) {8              Do{9String name=cursor.getstring (Cursor.getcolumnindex ("username"));TenString age=cursor.getstring (Cursor.getcolumnindex ("Age")); OneString sex=cursor.getstring (Cursor.getcolumnindex ("Sex")); AString phone=cursor.getstring (Cursor.getcolumnindex ("Phone")); -User=NewUserInfo (name,age,sex,phone); - list.add (user); the} while(Cursor.movetonext ()); -         } - cursor.close (); -         returnlist; +}

4. Inserting a database Mydatabasehelper databases inherits to Databasehelper

1 @Override2      Public voidsetuserinfo (mydatabasehelper database,userinfo user) {3Sqlitedatabase db=database.getwritabledatabase ();4Contentvalues values=Newcontentvalues ();5Values.put ("username", User.getname ());6Values.put ("Age", User.getage ());7Values.put ("Sex", User.getsex ());8Values.put ("Phone", User.getphone ());9Db.insert ("USERINFO",NULL, values);Ten}

5. Modify the Database

1 @Override2      Public voiddelectuserinfo (Mydatabasehelper database) {3Sqlitedatabase sqlitedatabase=database.getwritabledatabase ();4Contentvalues values=Newcontentvalues ();5Values.put ("Price", 10.99);//the field that needs to be modified Price field 10.99 Value6         7         //Modify the data? Position new string[]{modified? Data}8Sqlitedatabase.update ("USERINFO", Values, "Name=?",Newstring[]{"Thedavicicode"});9}

6. Delete data

1 @Override 2      Public void delectuserinfo (Mydatabasehelper database) {3         // delete data with ID less than 5 4         Sqlitedatabase db=database.getwritabledatabase (); 5         Db.delete ("USERINFO", "ID > 5",new string[]{"5"}); 6     }

SQLite use (Create, raise, increase, delete, change, check)