Android Database SQLite

SQLite database 

• In some cases, the file is not a valid multi-threaded data access if Ø is Ø -related applications that may change if the complex data structures, etc. Ø
• So, Android has built-in SQLite database support to bring
• Database package suite for creating them are private
• Database should not be used to store files
• Tip: In the SDK in the samples / NotePad can be found under the examples on how to use the database
• SQLite is a lightweight software library
• Implement a fully adapt to severe environmental database Ø Ø atomic weight of rugged durability Ø Ø independence
• Volume size of only a few thousand bytes
• Some SQL commands only partially supported, for example: ALTER, TABLE
• See http://www.sqlite.org for more information
• 
  
• *****************************************

Create Database

• Context.createDatabase (String name, int version, int mode, CursorFactory factory) to create a new database and returns a SQLiteDatabase object
• If the database can not be created, then throw FileNotFoundException exception
• New method to create SQLite database
• ****************************************

SQLiteDatabase myDataBase=this.openOrCreateDatabase("myDataBase.db",
                               MODE_PRIVATE, new CursorFactory(){
// Create a new database, the name  myDatabase, Model MODE_PRIVATE, mouse factory  
// The factory classes, an optional factory class  , When a query is called to instantiate a cursor  
    @Override
    public Cursor newCursor(SQLiteDatabase db,
            SQLiteCursorDriver masterQuery, String editTable,
            SQLiteQuery query) {
           // TODO Auto-generated method stub
            return null;
            }
});

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Delete Database    

Context.deleteDatabase (String name) Remove the specified name of the database

If the database is deleted successfully returned true, failure was false (such as a database does not exist) 

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// Create a file named  :myDataBase Database, Postfix  .db

SQLiteDatabase my_DataBase=this.openOrCreateDatabase("myDateBase.db",
                                                                      MODE_PRIVATE, null);
my_DataBase.close();// Don't forget to close the database  
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Open the database 

Context.openDatabase (String file, CursorFactory factory) to open an existing database and returns a SQLiteDatabase object 

If the database does not exist throw FileNotFoundException exception
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// Create a file named  :myDataBase Database, Postfix  .db
SQLiteDatabase my_DataBase=this.openOrCreateDatabase("myDateBase.db",                                                                      MODE_PRIVATE, null);
my_DataBase.close();// Don't forget to close the database  
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Non-query SQL commands 


SQLiteDatabase.execSQL (String sql) can be used to execute non-query SQL commands, these commands do not result

Including: CREATE TABLE / DROP TABLE / INSERT, etc.
For example:
Create a file named "test" and a table with two parameters
 
**********************************************
  

// Create a group named "test" and with two parameters table  
my_DataBase.execSQL("CREATE TABLE test (_id INTEGER PRIMARY KEY,
                                                        someNumber INTERGER);");
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2. In the database to insert a tuple 


/ In the database into a tuple  
my_DataBase.execSQL("INSERT INTO test (_id,someNumber) values(1,8);");
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3. Remove Table 



// Delete table  
my_DataBase.execSQL("DROP TABLE test");
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Query SQL command - Cursor Cursors 




Android use the cursor (Cursors) to navigate browse query results
Cursor (Cursors) to describe the object to be android.database.Cursor
A cursor (Cursors) is a simple pointer, which results from a query to the next tuple a tuple (or the previous or the first or ... ...)
Cursor (Cursors) Location Location in the moment it returned tuple data  

// In order to create a  Cursor( Cursor  ), You must perform a query, either by  SQL Use  rawQuery() Method  
        // Or a more elaborate methods, like  query() Method  
        Cursor cur=my_DataBase.rawQuery("SELECT * FORM test", null);
        if(cur!=null){// The cursor is not empty  
         // Returns the columns of the given name based on the 0-based  index, If this property returns the column does not exist  -1
         // Through their index to retrieve the property values  
         int numColumn=cur.getColumnIndex("someNumber");
         if(cur.moveToFirst()){
            //cur.moveToFirst() Let the cursor to the first row, if the cursor is pointing to the first row  , Returns  true
         do {
                     int num=cur.getInt(numColumn);// Get the current row of the value of this property  
                    /*Cursor Provides a different method to return a different data type cable  
                     For example,  getInt(int index)/getString(int index) And so on  */
                   /* Do something  */
               } while (cur.moveToNext());
                     /* Moves the cursor to the next line, if the cursor has passed the end of the result set  ,
                    That is, there are no rows can be moved, then the return  false*/
                  // Other possible move   previous()  And  first() Method  
               }
}
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database application sample 

Part code 



Enter the new contact information added to the database  

// The new import contact information into the database  
private void addToDataBase(String name_str2, String phone_str2, String email_str2, String address_str2) {
  // TODO Auto-generated method stub
  String sqlCmd="INSERT INTO myPhoneBook(Pname,Pphone,Pemail,Paddress) values('"+name_str2+"','"+phone_str2+"','"+email_str2+"','"+address_str2+"');";
  try {
   myPhoneBookDB.execSQL(sqlCmd);
   ShowNoteInformation(" Added successfully  !!");
  } catch (Exception e) {
   // TODO: handle exception
   ShowNoteInformation(" Add failed, record already exists  !!");
  }
  Log.i("MYTEST", sqlCmd);
}
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Database to find contact information

setMainScreen(R.layout.persionlist);
   setActionListener(R.layout.persionlist);
   // Instantiate the  ArrayList
   arraylistmap=new ArrayList
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The database to remove the phone records

ShowNoteInformation(" Delete the call log  ");
   myPhoneBookDB.execSQL("DELETE FROM myPhoneBook WHERE Pname='"+my_name+"';");
   Log.i("MYTEST", "DELETE FROM myPhoneBook WHERE Pname='"+my_name+"';");
   cleanShow();