【Android学习日记】(六) SQLite的简单实例

//实例类

public class ToDoDB extends SQLiteOpenHelper

{

private final static String DATABASE_NAME = "todo_db";

private final static int DATABASE_VERSION = 1;

private final static String TABLE_NAME = "todo_table";

public final static String FIELD_id = "_id";

public final static String FIELD_TEXT = "todo_text";

public ToDoDB(Context context)

{

super(context, DATABASE_NAME, null, DATABASE_VERSION); }

@Override

public void onCreate(SQLiteDatabase db)

{

/* 建立table */

String sql = "CREATE TABLE "

+ TABLE_NAME + " (" + FIELD_id +

" INTEGER primary key autoincrement, "

+ " " + FIELD_TEXT + " text)";

db.execSQL(sql);

}

@Override

public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion)

{

String sql = "DROP TABLE IF EXISTS "

+ TABLE_NAME; db.execSQL(sql);

onCreate(db);

}

public Cursor select()

{

SQLiteDatabase db = this.getReadableDatabase();

Cursor cursor = db.query(TABLE_NAME, null, null, null, null, null, null);

return cursor;

}

public long insert(String text)

{

SQLiteDatabase db = this.getWritableDatabase();

/* 将新增的值放入ContentValues */

ContentValues cv = new ContentValues();

cv.put(FIELD_TEXT, text);

long row = db.insert(TABLE_NAME, null, cv);

return row;

}

public void delete(int id)

{

SQLiteDatabase db = this.getWritableDatabase();

String where = FIELD_id + " = ?";

String[] whereValue = { Integer.toString(id) };

db.delete(TABLE_NAME, where, whereValue);

}

public void update(int id, String text)

{

SQLiteDatabase db = this.getWritableDatabase();

String where = FIELD_id + " = ?";

String[] whereValue = { Integer.toString(id) };

/* 将修改的值放入ContentValues */

ContentValues cv = new ContentValues();

cv.put(FIELD_TEXT, text);

db.update(TABLE_NAME, cv, where, whereValue);

}

}