java - 如何使用sqlite在java中创建条件

Question

我想设定一个条件，如果名字和姓氏在数据库中，则分数将被更新，否则数据将作为新用户正常插入。

我的代码:

public void data(View view)
{  
    scor=String.valueOf(qc1.scor);
    db.execSQL("UPDATE Student SET email='"+scor+"' WHERE fname ='"+exo.fname+"' AND lname ='"+exo.lname+"';");
     Toast toast = Toast.makeText(getApplicationContext(), "data updated", Toast.LENGTH_LONG);
     toast.show();
}

Answer 1

像这样的事情应该可以解决问题:

    Cursor cursor = db.rawQuery("select 1 from Student where fname=? AND lname =?", 
         new String[] { exo.fname, exo.lname });
    if(cursor.getCount() > 0) {
        // this means we found at least one entry that matches the name
        // update database here
    } else {
        // otherwise that user doesn't exist yet
        // insert into database here
    }