Usage of SQLite in Android storage mode

Android provides five storage methods: file, sharedPreference, network, SQLite, and ContentProvider. SQLite is a lightweight database with the advantages of independence, isolation, cross-platform, multi-language interface, and security. It is widely used at present. Now we will focus on the usage of SQLite in Android. First, I create a database operation class DataBaseHelper, let him inherit from SQLiteOpenHelper, and then re-write the two methods onCreate and onUpgrade. Copy code 1 package com. example. sqlitedb; 2 3 import android. content. context; 4 import android. database. sqlite. SQLiteDatabase; 5 import android. database. sqlite. SQLiteDatabase. cursorFactory; 6 import android. database. sqlite. SQLiteOpenHelper; 7 8 public class DataBaseHelper extends SQLiteOpenHelper {9 10 private final static String DBName = "sqlite3.db"; 11 private final static String TableName = ""; 12 private final static String firstname = "provincial"; 13 private final static String lastname = "number"; 14 15 public DataBaseHelper (Context context, String name, CursorFactory factory, 16 int version) {17 super (context, DBName, factory, version); 18 // TODO Auto-generated constructor stub19} 20 21 @ Override22 public void onCreate (SQLiteDatabase db) {23 // create table 24 String SQL = ("CREATE TABLE" + TableName + "(INTEGER PRIMARY KEY AUTOINCREMENT," + firstname + "VARCHAR," + lastname + "SMALLINT) "); 25 db.exe cSQL (SQL); 26} 27 28 @ Override29 public void onUpgrade (SQLiteDatabase db, int oldVersion, int newVersion) {30 // Delete TABLE 31 String SQL = "drop table if exists" + TableName; 32 db.exe cSQL (SQL); 34} 35 36} copy the code and, use SQL statements to perform some common SQLite operations, as shown in the following code: Copy code 1 @ Override 2 public void onCreate (SQLiteDatabase db) {3 // create table 4 String SQL = "create table city (integer primary key autoincrement, provincial VARCHAR, number SMALLINT)"; 5 db.exe cSQL (SQL ); 6 // insert data 7 // Method 1: execSQL 8 String sql1 = "insert into city (firstname, lastname) values ('beijing', '20 ')"; 9 db.exe cSQL (sql1); 10 // Method 2: Use insert11 ContentValues cv = new ContentValues (); 12 cv. put ("provincial", "Tianjin"); 13 cv. put ("number", 30); 14 db. insert ("city", null, cv); 15 // modify data 16 // 1. execSQL17 String sql2 = "update city set lastname = '25' where provincial = 'tianjin '"; 18 db.exe cSQL (sql2); 19 // 2. use insert20 ContentValues cv1 = new ContentValues (); 21 cv1.put ("provincial", "Beijing"); 22 cv1.put ("number", 30); 23 db. insert ("city", null, cv); 24 // delete data 25 String sql3 = "delete from city where provincial = 'beijing'"; 26 db.exe cSQL (sql3 ); 27 // close the database 28 db. close (); 29}