Storage of Android SQLite data

Generally in developmentProgramThe data storage function is often used. For example, when developing a program using Delphi, The INI file that stores simple settings of the program sometimes needs to be stored with simple settings in C # development, individuals are generally stored in XML and ini, but they are not as convenient as XML. These are simple data storage functions and such file storage is also supported in Android, however, here we mainly talk about using SQLite to store data. SQLite is a cross-platform database in a single file format, as we usually see the most access database, however, he has better platform support than access and supports paging. Now he is mainly used for embedded development.

During the development process, you can directly declare database objects for storage management,CodeAs follows:

Code

  Sqlitedatabase sqlitedb;  //  Database objects  
  Sqlitedb =     This  . Openorcreatedatabase (datebasename, mode_private,  Null  );

  //  Run the Code:  
  Sqlstring  =     "  Create Table  "     + Tablename
  +     "  (_ Id integer primary key, num integer, data text)  "  ;
Sqlitedb.exe csql (sqlstring ); 

 

This method requires more content to be processed. I personally feel that it is not very convenient. Just like the C # program we developed using sqlhelper, a similar class is also provided on the Android platform:

Sqliteopenhelper

We can implement this class to complete our operations, which is simpler and more efficient:

The Code is as follows:

Code

 Import  Android. content. context;
  Import  Android. database. cursor;
  Import  Android. database. SQLite. sqlitedatabase;
  Import  Android. database. SQLite. sqliteopenhelper;
  Import  Android. database. SQLite. sqlitedatabase. cursorfactory;

  Public     Class  Dbhelper Extends  Sqliteopenhelper {

  Private     Static     Final     Int  Db_version  =     1  ;

  Public  Dbhelper (context, string name, cursorfactory factory,
 Int  Version ){
  Super  (Context, name, factory, version );
  //  Todo auto-generated constructor stub  
  }

  Public  Dbhelper (context, string dbname ){
  Super  (Context, dbname,  Null  , Db_version );
}

@ Override
 Public     Void  Oncreate (sqlitedatabase dB ){
  //  Todo auto-generated method stub  
  
}

  Public     Void  Oncreate (sqlitedatabase dB, string createdbsql ){
  //  Todo auto-generated method stub  
 Db.exe csql (createdbsql );
}

@ Override
  Public     Void  Onupgrade (sqlitedatabase dB,  Int  Oldversion,  Int  Newversion ){
  //  Todo auto-generated method stub  
  
}

@ Override
  Public    Void  Onopen (sqlitedatabase dB ){
  //  Todo auto-generated method stub  
    Super  . Onopen (db );
}

  Public     Void  Insertintodb (sqlitedatabase dB, string SQL)
{
Db.exe csql (SQL );
}
  Public  Cursor opendb (sqlitedatabase dB, string SQL ){
 Return  DB. rawquery (SQL,  Null  );
}
} 

 

Here, we only do a simple writing. If we don't write too many methods, this is just a guide. We can extend this class to make it easier to use.

 

The following is a simple call:

Code

  //  Statement  
  Sqlitedatabase DB  =    Null  ;

Dbhelper  =     Null  ;

  //  Instantiation  
  Dbhelper  =     New  Dbhelper (  This  ,  " Dbname  "  );

  //  Method  
  Void  Createtable (){

String SQL  =     "  Create Table if not exists  "     +  Table_name  +    "  (  "     +  ID
  +     "  Text not null,  "     +  Name  +     " Text not null );  "  ;
Dbhelper. oncreate (dB, SQL );

}

  Void  Insertdb (string ID, string name ){
DB  =  Dbhelper. getwritabledatabase ();
String SQL  =     "  Insert  "     +  Table_name +     "  (  "     +  ID  +     "  ,  "     +  Name
  +    "  ) Values ('  "     +  ID  +     "  ','  "     +  Name  +     "  ') "  ;
Dbhelper. insertintodb (dB, SQL );
}

  Void  Getdb (){
DB  =  Dbhelper. getreadabledatabase ();
String SQL  =     "  Select * from  "     +  Table_name;
Cursor cursor  = Dbhelper. opendb (dB, SQL );
String text  =     ""  ;
  While  (Cursor. movetonext ()){
  For  (  Int  I  =     0  ; I  < Cursor. getcolumncount (); I  ++  ){
Text  + =  Cursor. getstring (I );
}
Text  + =     "  \ N  "  ;
}
Toast
. Maketext (  This  , Cursor. getcount ()  +    "  \ N  "     +  Text,
Toast. length_long). Show ();
} 

 

This is just a simple reference! Thank you for your criticism!