Question

我的程序每次运行时都能正常工作，除了第一个，在这段代码的最后一行转储：

public static SQLiteDatabase db;
private String[] niveles = new String [8];
static int nivelesSuperados = 1, col = 999;
public static Cursor c;
BDhelper dbhelper = new BDhelper(this, "BaseDatos", null, 1); 
db = dbhelper.getWritableDatabase();
c = db.rawQuery("SELECT nivel FROM Tabla", null);
if (c.moveToLast()==false) { //if there aren't rows to get
    ContentValues nuevoNivel = new ContentValues();
    nuevoNivel.put("nivel", "nivel1");
    db.insert("Tabla", null, nuevoNivel);
    c.moveToLast();
}
col = c.getColumnIndex("nivel");
niveles[0] = c.getString(col);

看起来很容易，但我找不到解决方案

Answer 1

将数据插入数据库时，它不会影响您已拥有的查询，即Cursor。您将不得不再次查询数据库以获取包含所需数据的新Cursor。但是考虑到你只是放置了数据，在读取数据库中找到你已经知道的值并没有任何意义。

所以，改变

c = db.rawQuery("SELECT nivel FROM Tabla", null);
if (c.moveToLast()==false) { //if there aren't rows to get
    ContentValues nuevoNivel = new ContentValues();
    nuevoNivel.put("nivel", "nivel1");
    db.insert("Tabla", null, nuevoNivel);
    c.moveToLast();
}
col = c.getColumnIndex("nivel");
niveles[0] = c.getString(col);

类似

c = db.rawQuery("SELECT nivel FROM Tabla", null);
if (c.moveToLast()==false) { //if there aren't rows to get
    ContentValues nuevoNivel = new ContentValues();
    nuevoNivel.put("nivel", "nivel1");
    db.insert("Tabla", null, nuevoNivel);
    niveles[0] = "nivel1";
} else {
    col = c.getColumnIndex("nivel");
    niveles[0] = c.getString(col);
}

SQLite：首次运行时光标出错

1 个答案: