java - Android 应用程序因 SQL 查询而崩溃

Question

在此函数中，我尝试获取 Table 中的行数。

public int getSetCount(){
    SQLiteDatabase db = this.getWritableDatabase();
    String query = "SELECT " +KEY_SET_ID+" * FROM "+TABLE_SETS;
    Cursor mcursor = db.rawQuery(query, null);
    mcursor.moveToFirst();
    return mcursor.getInt(0);

}

logCat 打印出类似这样的内容

   sqlite returned: error code = 1, msg = near "FROM": syntax error

在此函数中，我将查找具有给定 ID 的名称。

public String getSetName (int ID){
    SQLiteDatabase db = this.getReadableDatabase();
    Cursor cursor = db.rawQuery("SELECT * FROM "+TABLE_SETS+" WHERE "+KEY_SET_ID+" =? "+ID, null);
    if (cursor != null)
        cursor.moveToFirst();
    return cursor.getString(0);
}

这些函数有什么问题，请告诉我？根据所有论坛和教程，我所做的一切都是正确的。

Answer 1

看来你的SQL语句写得不正确。只需更改以下行:

   String query = "SELECT " +KEY_SET_ID+" * FROM "+TABLE_SETS;

至:

String query = "SELECT " +KEY_SET_ID+" FROM "+TABLE_SETS;