Using the SQLite database in Android

Project Source Download

Https://github.com/Wang-Jun-Chao/AndroidProjects

SQLite database

Lightweight relational database

The api:sqliteopenhelper to use to create the database

You must define a construction method:

//arg1:数据库文件的名字
//arg2:游标工厂
//arg3:数据库版本
public MyOpenHelper(Context context, String name, CursorFactory factory, int version){}

Called when a database is created: OnCreate method

Called when the database is upgraded: Onupgrade method

Creating a Database

    
    MyOpenHelper oh =  MyOpenHelper(getContext(), , , );
    
    SQLiteDatabase db = oh.getWritableDatabase();

Getwritabledatabase (): Open a writable database

Getreadabledatabase (): Open a read-only database when disk space is low, otherwise open a writable database

Create a table when you create a database

        public void onCreate(SQLiteDatabase db) {
            // TODO Auto-generated method stub
            db.execSQL("  person (_id    autoincrement, 
                    name (), phone (), money ())

Database additions and deletions to check

SQL statement

*   person (name, phone, money)  (, , );
*   person  name =   _id = ;
*  person  money =   name = ;
*  name, phone  person  name = ;

Execute SQL statement implementation and deletion and change check

        
        db.execSQL(,  []{, , });
        
        Cursor cs = db.rawQuery(,  []{});

This method is called before the test method executes

          ()  Exception {
            .setUp();
            
            oh =  MyOpenHelper(getContext(), , , );
        }

Use API to implement additions and deletions

Insert

        
        ContentValues cv =  ContentValues();
        cv.put(, );
        cv.put(, );
        cv.put(, );
        
         i = db.insert(, , cv);

Delete

        
         i = db.(, ,  String[]{, });

Modify

        ContentValues cv =  ContentValues();
        cv.put(, );
         i = db.update(, cv, ,  []{});

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Inquire

        
        
        
        Cursor cs = db.query(,  []{, }, ,  []{}, , , );
        (cs.moveToNext()){
            
             name = cs.getString(cs.getColumnIndex());
             money = cs.getString(cs.getColumnIndex());
            System.out.println(name +  + money);
        }

Transaction

Ensure that multiple SQL statements succeed at the same time or fail at the same time

Most common cases: bank transfers

Transaction API

        try {
            
            dbbeginTransaction();
            
            
            dbsetTransactionSuccessful();
        } finally{
            
            
            dbendTransaction();
        }

Display data from the database to the screen

Arbitrarily insert some data

Define Business Bean:Person.java

Read all data from the database

        Cursor cs = db.query(, , , , , , );
        (cs.moveToNext()){
             name = cs.getString(cs.getColumnIndex());
             phone = cs.getString(cs.getColumnIndex());
             money = cs.getString(cs.getColumnIndex());
            
            Person p =  Person(name, phone, money);
            
            people.add(p);
        }

Display the data from the collection to the screen

         LinearLayout ll = (LinearLayout) findViewById(R.id.ll);
         (Person p : people){
             
             TextView tv =  TextView();
             tv.setText(p.toString());
             
             ll.addView(tv);
         }

Page-Search

        Cursor cs = db.query(, , , , , , , );