Question

已更新

我正在尝试创建一个DBHelper类并复制旧代码中的所有内容。但是，我似乎无法插入此内容。我不知道原因，我试图重新观看数据库中的教程，但我没有看到我的代码有任何错误。你能查一下这段代码吗？

DBHelper.Java

public class DBHelper extends SQLiteOpenHelper {

public static final String DATABASE_NAME = "DBName.db";
public static final String TABLE_NAME = "tblSample";
public static final String COL_1 = "ID";
public static final String COL_2= "Title";
public static final String COL_3 = "Content";

public DBHelper(Context context) {
    super(context, DATABASE_NAME, null, 1);
}

@Override
public void onCreate(SQLiteDatabase db) {
    db.execSQL("create table IF NOT EXISTS " + TABLE_NAME + " " +
            "(id integer primary key autoincrement, Title text, Content text) ");
}

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    db.execSQL("DROP TABLE IF EXISTS " + TABLE_NAME);
    onCreate(db);
}

public boolean insertValue (String title, String cnt) {

    SQLiteDatabase db = this.getWritableDatabase();
    ContentValues contentValues = new ContentValues();
    contentValues.put(COL_2, title);
    contentValues.put(COL_3, cnt);
    long result = db.insert(TABLE_NAME, null, contentValues);
    return result != -1;
    //note this code is returning false
}

public Cursor selectSample(){
    //I also tried to use this.getReadableDatabase();
    SQLiteDatabase db = this.getWritableDatabase();
    Cursor res =  db.rawQuery( "select * from " + TABLE_NAME, null );
    return res;
    //this is returning 0 count 
}

}

这是我在MainActivity.java

上的代码

    mydb = new DBHelper(this);
    boolean hasError = mydb.insertValue("Title1", "content1");
    if(!hasError){
        Toast.makeText(getApplicationContext(), "No Error:",Toast.LENGTH_LONG).show();
    }else{
        Toast.makeText(getApplicationContext(), "Not Inserted:",Toast.LENGTH_LONG).show();
    }

此代码显示Not Inserted:含义，我无法插入db

您能否告诉我原因或至少告诉我如何在插入数据时显示错误消息。这样我至少可以意识到错误

SQL Lite无法插入值

0 个答案: