SQLite是一款輕量級(jí)的關(guān)系型數(shù)據(jù)庫(kù)。無(wú)需服務(wù)進(jìn)程谒臼，無(wú)需安裝和配置朝刊，支持事務(wù)處理。它的運(yùn)算速度快蜈缤，占用資源少拾氓，適合在存儲(chǔ)大量復(fù)雜的關(guān)系型數(shù)據(jù)的時(shí)候使用。

一底哥、SQLite數(shù)據(jù)庫(kù)使用

（1）使用幫助類(lèi)SQLiteOpenHelper創(chuàng)建數(shù)據(jù)庫(kù)

• SQLiteOpenHelper是SQLiteDatabase的幫助類(lèi)咙鞍， 用于管理數(shù)據(jù)庫(kù)的創(chuàng)建和升級(jí)。
• 自定義幫助類(lèi)繼承SQLiteOpenHelper趾徽，并重寫(xiě)onCreate()和 onUpgrade()续滋，分別在這兩個(gè)方法中去實(shí)現(xiàn)創(chuàng)建、升級(jí)數(shù)據(jù)庫(kù)的邏輯孵奶。
• 調(diào)用幫助類(lèi)對(duì)象的getReadableDatabase() 和getWritableDatabase()去創(chuàng)建或打開(kāi)一個(gè)現(xiàn)有的數(shù)據(jù)庫(kù)疲酌，并返回一個(gè)可對(duì)數(shù)據(jù)庫(kù)操作的SQLiteDatabase。
• 在onCreate方法中調(diào)用SQLiteDatabase的方法execSQL()創(chuàng)建數(shù)據(jù)庫(kù)。execSQL()可以接受和處理SQL語(yǔ)句朗恳。

public class MySQLiteHelper extends SQLiteOpenHelper {
    public static final String CREATE_MEMBER = "create table member(id integer primary key autoincrement, name text, sex text, age integer)";
    public static final String CREATE_INTEREST = "create table interest(id integer primary key autoincrement,content text)";
    public static final String CREATE_MEMBER_AGE = "alter table member add column age integer";

    public MySQLiteHelper(@Nullable Context context, @Nullable String name, @Nullable SQLiteDatabase.CursorFactory factory, int version) {
        super(context, name, factory, version);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        //創(chuàng)建member表
        db.execSQL(CREATE_MEMBER);
        //創(chuàng)建interest表
        db.execSQL(CREATE_INTEREST);
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        switch (oldVersion) {
            case 1:
                //升級(jí)數(shù)據(jù)庫(kù)增加表
                db.execSQL(CREATE_INTEREST);
            case 2:
                //升級(jí)數(shù)據(jù)庫(kù)增加表中字段age
                db.execSQL(CREATE_MEMBER_AGE);
                break;
            default:
        }
    }
}

（2）操作數(shù)據(jù)表

    //獲取到SQLiteDatabase的實(shí)例
    SQLiteOpenHelper dbHelper = new MySQLiteHelper(this, "demo.db", null, 1);
    
    private void insert() {
        SQLiteDatabase db = dbHelper.getWritableDatabase();
        ContentValues values = new ContentValues();
        values.put("name", "黃渤");
        values.put("sex", "男");
        values.put("age", 34);
        db.insert("member", null, values);
        values.clear();

        db.execSQL("insert into member(name,sex,age) values('黃渤','男',34)");
    }

    private void update() {
        SQLiteDatabase db = dbHelper.getWritableDatabase();
        ContentValues values = new ContentValues();
        values.put("name", "岳云鵬");
        db.update("member", values, "id = ?", new String[]{"1"});
        values.clear();

        db.execSQL("update member SET id = '1' WHERE name = '岳云鵬'");
    }

    private void delete() {
        SQLiteDatabase db = dbHelper.getWritableDatabase();
        db.delete("member", "name= ?", new String[]{"岳云鵬"});

        db.execSQL("delete from member where name = '岳云鵬'");
    }

    @SuppressLint("Recycle")
    private void rawQuery() {
        SQLiteDatabase db = dbHelper.getReadableDatabase();
        //查詢member表中所有數(shù)據(jù)
        Cursor cursor1 = db.query("member", null, null, null, null, null, null);
        //查詢member表中年齡大于30的數(shù)據(jù)
        Cursor cursor2 = db.query("member", null, "age > ?", new String[]{"30"}, null, null, null);

        Cursor cursor3 = db.rawQuery("select * from member", null);

        //從Cursor對(duì)象中取出數(shù)據(jù)
        List<Member> memberList = new ArrayList<Member>();
        if (cursor1 != null && cursor1.moveToFirst()) {
            do {
                int id = cursor1.getInt(cursor1.getColumnIndex("id"));
                String name= cursor1.getString(cursor1.getColumnIndex("name"));
                String sex= cursor1.getString(cursor1.getColumnIndex("sex"));
                int age= cursor1.getInt(cursor1.getColumnIndex("age"));
                Member member = new Member();
                member.setId(id);
                member.setName(name);
                member.setSex(sex);
                member.setAge(age);
                memberList.add(member);
            } while (cursor1.moveToNext());
        }
    }

SQLite源碼解析