1.SQLite的介紹

        sqlite是一款輕量型的資料庫，不需要安裝且不依賴第三方軟體，除了主流作業系統 windows，linux之後，SQLite還支援其它一些不常用的操作系 統。 當然sqlite也是Android原生資料庫，既然sqlite這麼好，那麼今天我就帶著大家一起探索一下sqlite的真面目。

2.SQLite的使用步驟

class SQLiteDBHelper extends SQLiteOpenHelper{
   private static final int VERSION 
 
= 1;
   private static final String DB_NAME = "persons.db";
   public SQLiteDBHelper(Context context) {
      //在構造器中建立資料庫
super(context,DB_NAME,null,VERSION);
}

   @Override
public void onCreate(SQLiteDatabase sqlitedatabase) {
      //在oncreate中建立表
sqlitedatabase.execSQL("CREATE TABLE IF NOT EXISTS " 
 
+ TABLE_NAME + " (" + COLUMN_ID + " INTEGER PRIMARY KEY,name TEXT,age INTEGER)");
}

   @Override
public void onUpgrade(SQLiteDatabase sqlitedatabase, int i, int j) {
      //修改表,建立新表,資料備份,刪除表
sqlitedatabase.execSQL("ALTER TABLE " + TABLE_NAME + " RENAME TO PERSON_TEMP");
sqlitedatabase.execSQL("CREATE TABLE " 
 
+ TABLE_NAME + " (_id integer primary key,name varchar(20),age integer,sex varchar(2))");
sqlitedatabase.execSQL("INSERT INTO " + TABLE_NAME + " (_id,name,age,sex) SELECT _id,name,age,'女' FROM PERSON_TEMP");
}
}

//在類的構造方法中初始化Context,SQLiteDatabase
public SQLiteDAO(Context cxt) {
   mContext = cxt;
sqliteDBHelper = new SQLiteDBHelper(mContext);
//建立資料庫
sqliteDataBase = sqliteDBHelper.getWritableDatabase();
}

public class Person implements java.io.Serializable{

   private static final long serialVersionUID = 1L;
   private int id;
   private String name;
   private int age;
   public Person(){}
   
   public int getId() {
      return id;
}
   
   public void setId(int id) {
      this.id = id;
}
   
   public String getName() {
      return name;
}
   
   public void setName(String name) {
      this.name = name;
}
   
   public int getAge() {
      return age;
}
   
   public void setAge(int age) {
      this.age = age;
}
}

3.SQLite的具體應用

//新增資料
public void insertPerson(Person person) {
   String INSERT_SQL = "INSERT INTO " + TABLE_NAME + " (" + COLUMN_NAME
+ "," + COLUMN_AGE + ") " + "VALUES (" + "'" + person.getName()
                   + "'" + "," + person.getAge() + ")";
sqliteDataBase.execSQL(INSERT_SQL);

 ContentValues cv = new ContentValues();
 cv.put(COLUMN_NAME, person.getName());
 cv.put(COLUMN_AGE, person.getAge());
 //當cv引數為空或者沒有內容的時候,insert會失敗,為了防止這種情況發生,
 // 要在第二個引數設定一個列名,當要插入的行為空行時,將指定的列名值設定為null
 sqliteDataBase.insert(TABLE_NAME, null, cv);

//刪除資料
public void deletePerson(int id) {
   String DELETE_SQL = "DELETE FROM " + TABLE_NAME + " WHERE " + COLUMN_ID
+ " = " + id;
sqliteDataBase.execSQL(DELETE_SQL);}

sqliteDataBase.delete(TABLE_NAME, COLUMN_ID + "=?", new String[]{String.valueOf(id)});

//修改資料
public void updatePerson(Person person) {
   String UPDATE_SQL = "UPDATE " + TABLE_NAME + " SET " + COLUMN_NAME
+ " = " + "'" + person.getName() + "'" + " WHERE " + COLUMN_ID
+ " = " + person.getId();
sqliteDataBase.execSQL(UPDATE_SQL);
}

ContentValues cv = new ContentValues();
cv.put(COLUMN_NAME, person.getName());
sqliteDataBase.update(TABLE_NAME, cv, COLUMN_ID + "=?", new String[]{String.valueOf(person.getId())});

//查詢單條資料
public ArrayList<Person> findPerson(int sid) {
   ArrayList<Person> personList = new ArrayList<Person>();
Person person = new Person();
Cursor cursor = sqliteDataBase.rawQuery("SELECT * FROM " + TABLE_NAME
+ " WHERE " + COLUMN_ID + " = ?", new String[] { String
               .valueOf(sid) });
   while (cursor.moveToNext()) {
      int id = cursor.getInt(cursor.getColumnIndex(COLUMN_ID));
String name = cursor.getString(cursor.getColumnIndex(COLUMN_NAME));
      int age = cursor.getInt(cursor.getColumnIndex(COLUMN_AGE));
person.setId(id);
person.setName(name);
person.setAge(age);
personList.add(person);
}
   cursor.close();
   return personList;
}

//查詢所有資料   
public ArrayList<Person> listPerson() {
   ArrayList<Person> personList = new ArrayList<Person>();
Cursor cursor = sqliteDataBase.rawQuery("SELECT * FROM " + TABLE_NAME
+ " WHERE " + COLUMN_ID + " IS NOT ?", new String[] { "NULL" });
   while (cursor.moveToNext()) {
      int id = cursor.getInt(cursor.getColumnIndex(COLUMN_ID));
String name = cursor.getString(cursor.getColumnIndex(COLUMN_NAME));
      int age = cursor.getInt(cursor.getColumnIndex(COLUMN_AGE));
Person person = new Person();
person.setId(id);
person.setName(name);
person.setAge(age);
personList.add(person);
}
   cursor.close();
   return personList;
}

public class MainActivity extends AppCompatActivity {

    @Override
protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//開啟或建立sqlite.db資料庫
SQLiteDatabase db = openOrCreateDatabase("sqlite.db",MODE_PRIVATE,null);
db.execSQL("DROP TABLE IF EXISTS student");
//建立學生表
db.execSQL("CREATE TABLE student (_id INTEGER PRIMARY KEY AUTOINCREMENT,name VARCHAR , age SMALLINT)");Student student = new Student();
student.setName("xiaoxing");
student.setAge(23);
//插入資料
db.execSQL("INSERT INTO student values(null,?,?)",new Object[]{student.getName(),student.getAge()});
student.setName("wangxiaoer");
student.setAge(24);
//ContentValues以鍵值對的形式存放資料
ContentValues cv = new ContentValues();
cv.put("name",student.getName());
cv.put("age",student.getAge());
//插入contentValue的資料
db.insert("student",null,cv);
//修改資料
cv = new ContentValues();
cv.put("age",30);
db.update("student",cv,"name = ?",new String[]{"xiaoming"});
//查詢資料
Cursor c = db.rawQuery("SELECT * FROM student WHERE age > ?",new String[]{"20"});
        while(c.moveToNext()){

            int _id = c.getInt(c.getColumnIndex("_id"));
String name = c.getString(c.getColumnIndex("name"));
            int age = c.getInt(c.getColumnIndex("age"));
Log.i("db","_d=>"+_id+",name=>"+name+",age=>"+age);
}
        c.close();
db.delete("student","name=?",new String[]{"wangxiaoer"});db.close();}
}