Android database SQlite

I have been engaged in Android development for a long time, but I have not yet written the basics of sqlite, which will be expanded later...

 

Package com. king. android. db;

Import android. content. ContentValues;
Import android. content. Context;
Import android. database. Cursor;
Import android. database. SQLException;
Import android. database. sqlite. SQLiteDatabase;
Import android. database. sqlite. SQLiteOpenHelper;

/**

* Description: database...
* Author: Andy. Liu
* Time: 10:37:27
**/
Public class MyDataBaseAdapter {

Private static final String TAG = "MyDataBaseAdapter ";

Private Context mContext = null;

Public static final String KEY_ID = "_ id ";

Public static final String KEY_NUM = "num ";

Public static final String KEY_DATA = "data ";

Private static final String DB_NAME = "king. db ";

Private static final String TABLE_KING = "king ";

Private static final int DB_VERSION = 1;


// Create a table statement
Private static final String CREATE_TAB_KING = null;

// Execute open () to open the database and save the Returned Database Object
Private SQLiteDatabase mSQlLiteDatabase = null;

// Inherited by SQLiteOpenHelper
Private DatabaseHelper mDatabaseHelper = null;

// Inherit from SQLiteOpenHelper
Private static class DatabaseHelper extends SQLiteOpenHelper {

// Create a database using the constructor
Public DatabaseHelper (Context context ){
/**
* When getWriteableDatabase () and getReadableDatabase () are called, a database is created.
*/
Super (context, DB_NAME, null, DB_VERSION );

}

@ Override/* create a data table */
Public void onCreate (SQLiteDatabase db ){
Db.exe cSQL (CREATE_TAB_KING );
}

@ Override // upgrade the database
Public void onUpgrade (SQLiteDatabase db, int oldVersion, int newVersion ){
Db.exe cSQL ("drop table if exists notes ");
OnCreate (db );
}
}
// The constructor obtains the Context
Public MyDataBaseAdapter (Context context ){
This. mContext = context;
}

// Open the database and return the database object
Public void open () throws SQLException {
MDatabaseHelper = new DatabaseHelper (mContext );
MSQlLiteDatabase = mDatabaseHelper. getWritableDatabase ();
}

// Close the database
Public void close (){
MDatabaseHelper. close ();
}

// Insert a data entry
Public long insertData (int num, String data ){
ContentValues initValues = new ContentValues ();
InitValues. put (KEY_NUM, num );
InitValues. put (KEY_DATA, data );
Return mSQlLiteDatabase. insert (TABLE_KING, KEY_ID, initValues );
}

// Delete a piece of data
Public boolean deleteData (long rowId ){
Return mSQlLiteDatabase. delete (TABLE_KING, KEY_ID + "=" + rowId, null)> 0;
}

// Query all data through Cursor
Public Cursor fetchAllData (){
Return mSQlLiteDatabase. query (TABLE_KING, new String [] {KEY_ID, KEY_NUM, KEY_DATA}, null );
}

// Query the specified data
Public Cursor fetchData (long rowId ){
Cursor mCursor = mSQlLiteDatabase. query (true, TABLE_KING, new String [] {KEY_ID, KEY_NUM, KEY_DATA}, KEY_ID + "=" + rowId, null, null );
If (null! = MCursor ){
MCursor. moveToFirst ();
}
Return mCursor;
}

// Update a piece of data
Public boolean updateData (long rowId, int num, String data ){
ContentValues args = new ContentValues ();
Args. put (KEY_NUM, num );
Args. put (KEY_DATA, data );
Return mSQlLiteDatabase. update (TABLE_KING, args, KEY_ID + "=" + rowId, null)> 0;
}

}