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我用這個java類來創建一個數據庫:Android的SQL查詢語法
public class DBhelper extends SQLiteOpenHelper {
private static final String DB_NAME = "grades.db";
private static final int DB_VERSION = 1;
public static final String TABELLA_RICETTE = "TabellaRicette";
public static final String COL_ID="ColonnaId";
public static final String COL_NOME="ColonnaNome";
public static final String COL_TIPO = "ColonnaTipo";
public static final String COL_IMMAGINE = "ColonnaImmagine";
public static final String COL_ATTRIBUTI="ColonnaAttributi";
public static final String COL_INGREDIENTI = "ColonnaIngredienti";
public static final String COL_DIFFICOLTA="ColonnaDifficolta";
public static final String COL_DESCRIZIONE="ColonnaDescrizione";
public DBhelper(Context context){
super(context, DB_NAME, null, DB_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db) {
String sql_tab = "create table " + TABELLA_RICETTE + "(" +
COL_ID + " integer primary key autoincrement, " +
COL_NOME + " text not null, " +
COL_TIPO + " text not null, " +
COL_IMMAGINE + " text not null, " +
COL_ATTRIBUTI + " text not null, " +
COL_INGREDIENTI + " text not null, " +
COL_DIFFICOLTA + " text not null, " +
COL_DESCRIZIONE + " text not null " +
");";
db.execSQL(sql_tab);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
}
我用這個函數來獲取數據庫中的所有信息:
public Cursor get_all() {
return getWritableDatabase().query(TABELLA_RICETTE, null, null, null, null, null, null);
}
現在我會做出更選擇具有COL_TIPO
中的特定String s1
和COL_DIFFICOLTA
中的String s2
的所有元素。
我試着寫一些東西,但也許我的語法錯了。
你能幫助我使用這個功能嗎?
那麼究竟什麼是這裏的問題? –