SQLite Quick Start [Android entry 4]

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1. SQLite Introduction

Http://www.sqlite.org/

A very small database provides a relatively complete Relational Database

2. sqliteopenhelper usage

getReadableDatabase ()

       getWritableDatabase ()

       onCreate (SQLiteDatabase db)

       onOpen (SQLiteDatabase db)

       onUpgrade (SQLiteDatabase db, int oldVersion, int newVersion)

       close ()

3. # sqlite3 test_mars_db
 
    sqlite> .schema command: all start with dots. Shows which tables exist in the current database, and how the tables are created!
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1. Operation steps of SQLite database:

    (1) First create a class,

extends SQLiteOpenHelper
    (2)

Write a constructor, a constructor with four parameters (Context context, String name,
                                 CursorFactory factory, int version) {

             super (context, name, factory, version);
        }

        Constructor with two parameters (Context context, String name) {
              this (context, name, 1);
        }
         
        Three parameter constructor (Context context, String name, int version) {
              this (context, name, null, version);
        }

   
     (3)

@override OnCreate method (SQLiteDatabase db) {
              db.execSQL ("create table user (id int, name varchar (20))");
         }

         @override OnUpgrade (SQLiteDatabase db, int oldVersion, int newVersion) {
              Can write some operations
         }

2.// What is written in the listen method of the create database button
  

onClick (View v) in createDatabaseButtonListener {
       // Explain, DatabaseHelper is the class that inherits SQLiteOpenHelper above
      

 DatabaseHelper dbHelper = new DatabaseHelper (current class.this, "test_daming");
       SQLiteDatabase db = dbHelper.getReadableDatabase ();
   }

3.// What is written in the listen method of the update database button
  

onClick (View v) in updateDatabaseButtonListener {

       DatabaseHelper dbHelper = new DatabaseHelper (current class.this, "test_daming", 2);
       SQLiteDatabase db = dbHelper.getReadableDatabase ();
   }

4, / / Insert the database table operation, written in the Button button listen method
  

 onClick (View v) in insertButtonListener {
       ContentValues values = new ContentValues ();
       values.put ("id", 1);
       values.put ("name", "daming");
       DatabaseHelper dbHelper = new DatabaseHelper (current class.this, "test_daming");
       SQLiteDatabase db = dbHelper.getWritableDatabase ();
       db.insert ("user", null, values);
   }
5, / / Update the database table operation, written in the Button button listen method
 

  onClick (View v) in updateButtonListener {
       DatabaseHelper dbHelper = new DatabaseHelper (current class.this, "database name");
       SQLiteDatabase db = dbHelper.getWritableDatabase ();
       ContentValues values = new ContentValues ();
       values.put ("name", "Peking");
       db.update ("user", values, "id =?", new String [] {"1"});
   }
6, / / Find the database table operation, written in the Button button listen method
 

  onClick (View v) in queryButtonListener {
       DatabaseHelper dbHelper = new DatabaseHelper (current class.this, data name ");
       SQLiteDatabase db = dbHelper.getWritableDatabse ();
       Cursor cursor = db.query ("user", new String [] ("id", "name", "id =?", New
                                String [] {"1"}, "id", "id", "id"}));
       while (cursor.moveToNext ()) {
           String name = cursor.getString (cursor.getColumnIndex ("name"));
           System.out.println ("query->" + name);
       }
   }
7, / / delete the database table operation, written in the Button button listen method
 

  onClick (View v) in deleteButtonListener {
       DatabaseHelper dbHelper = new DatabaseHelper (current class.this, data name ");
       SQLiteDatabase db = dbHelper.getWritableDatabse ();
       db.delete ("student", "id =?", new String [] {"1"});
       System.out.println ("Delete the record with id = 1 in the table");
   }