android 之 SQLite

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创建MyDatabaseHelper继承自SQLiteOpenHelper:

 public class MyDatabaseHelper extends SQLiteOpenHelper {//建表    public static final String CREATE_BOOK = "create table Book("    +"id integer primary key autoincrement,"    +"author text,"    +"price real,"    +"pages integer,"    +"name text)";//新增表    public static final String CREATE_CATEGORY = "create table Category("    +" id integer primary key autoincrement,"    +" category_name text,"    +" category_code integer,"    +" category_height integer)";    private Context mContext;    public MyDatabaseHelper(Context context, String name, SQLiteDatabase.CursorFactory factory, int version) {        super(context, name, factory, version);        mContext = context;    }    @Override    public void onCreate(SQLiteDatabase sqLiteDatabase) {        sqLiteDatabase.execSQL(CREATE_BOOK);        sqLiteDatabase.execSQL(CREATE_CATEGORY);        Toast.makeText(mContext,"Create succeed",Toast.LENGTH_SHORT).show();    }//更新数据库版本    @Override    public void onUpgrade(SQLiteDatabase sqLiteDatabase, int i, int i1) {        sqLiteDatabase.execSQL("drop table if exists Book");        sqLiteDatabase.execSQL("drop table if exists Categoty");    }}

执行CRUD操作活动页面：

public class FirstActivity extends BaseActivity {private MyDatabaseHelper database;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        Log.d("FirstActivity", "Task id is" + getTaskId());        setContentView(R.layout.first_layout);        database = new MyDatabaseHelper(this, "BookS.db", null, 2);//建表        Button button = (Button) findViewById(R.id.Create_database);        button.setOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View view) {                database.getWritableDatabase();            }        });//增加数据        Button addData = (Button) findViewById(R.id.add_data);        addData.setOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View view) {                SQLiteDatabase db = database.getWritableDatabase();                ContentValues values = new ContentValues();                values.put("name", "The dA BAOBO");                values.put("author", "hanahm");                values.put("pages", 123423);                values.put("price", 12.90);                db.insert("Book", null, values);            }        });//更新数据        Button updateButton = (Button) findViewById(R.id.update_data);        updateButton.setOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View view) {                SQLiteDatabase db = database.getWritableDatabase();                ContentValues values = new ContentValues();                values.put("price", 10.99);                db.update("Book", values, "name = ?", new String[]{"The dA BAOBO"});            }        });//删除表中数据        Button deleteButton = (Button) findViewById(R.id.delete_data);        deleteButton.setOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View view) {                SQLiteDatabase db = database.getWritableDatabase();                db.delete("Book", "pages > ?", new String[]{"500"});            }        });//查询表中数据        Button queryButton = (Button) findViewById(R.id.query_data);        queryButton.setOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View view) {                SQLiteDatabase db = database.getWritableDatabase();                //查询表中所有的数据                Cursor cursor = db.query("Book", null, null, null, null, null, null);                if (cursor.moveToFirst()) {                    do {                        //遍历cursor对象，取出数据并打印                        String name = cursor.getString(cursor.getColumnIndex("name"));                        String cuthor = cursor.getString(cursor.getColumnIndex("author"));                        int pages = cursor.getInt(cursor.getColumnIndex("pages"));                        double price = cursor.getDouble(cursor.getColumnIndex("price"));                        Log.d("FirstActivity", "book name is " + name);                        Log.d("FirstActivity", "book author is " + cuthor);                        Log.d("FirstActivity", "book pages is " + pages);                        Log.d("FirstActivity", "book price is " + price);                    }while (cursor.moveToNext());                }                cursor.close();            }        });        }}}

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