Question

我是android SQLite的初学者。以下是我从一个网站获得的学生数据库的代码。我理解代码，但我不知道如何更新和删除任何行。有人可以帮忙吗？我应该添加什么以下代码？

public class MainActivity extends Activity {
String fname,lname,email;
SQLiteDatabase db;
TableRow tableRow;
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    db=openOrCreateDatabase("MyDB1",MODE_PRIVATE, null);
    db.execSQL("CREATE TABLE IF NOT EXISTS Student(fname VARCHAR,lname VARCHAR,email VARCHAR);");
}
public void data(View view)
{
EditText edittext1=(EditText )findViewById(R.id.firstname);
EditText edittext2=(EditText )findViewById(R.id.lastname);
EditText edittext3=(EditText )findViewById(R.id.email);
fname=edittext1.getText().toString();
lname=edittext2.getText().toString();
email=edittext3.getText().toString();
db.execSQL("INSERT INTO  Student VALUES('"+fname+"','"+lname+"','"+email+"');"); 
}
public void showdata(View view)
{
Cursor c=db.rawQuery("SELECT * from Student", null);
 int count= c.getCount();
c.moveToFirst();
TableLayout tableLayout = new TableLayout(getApplicationContext());
tableLayout.setVerticalScrollBarEnabled(true);
TableRow tableRow;
TextView textView,textView1,textView2,textView3,textView4,textView5;
tableRow = new TableRow(getApplicationContext());
textView=new TextView(getApplicationContext());
textView.setText("Firstname");
textView.setTextColor(Color.RED);
textView.setTypeface(null, Typeface.BOLD);
 textView.setPadding(20, 20, 20, 20);
tableRow.addView(textView);
textView4=new TextView(getApplicationContext());
textView4.setText("LastName");
textView4.setTextColor(Color.RED);
textView4.setTypeface(null, Typeface.BOLD);
 textView4.setPadding(20, 20, 20, 20);
tableRow.addView(textView4);
textView5=new TextView(getApplicationContext());
textView5.setText("Email");
textView5.setTextColor(Color.RED);
textView5.setTypeface(null, Typeface.BOLD);
textView5.setPadding(20, 20, 20, 20);
tableRow.addView(textView5);
tableLayout.addView(tableRow);
 for (Integer j = 0; j < count; j++)
 {
     tableRow = new TableRow(getApplicationContext());
     textView1 = new TextView(getApplicationContext());
     textView1.setText(c.getString(c.getColumnIndex("fname")));
     textView2 = new TextView(getApplicationContext());
     textView2.setText(c.getString(c.getColumnIndex("lname")));
     textView3 = new TextView(getApplicationContext());
     textView3.setText(c.getString(c.getColumnIndex("email")));
     textView1.setPadding(20, 20, 20, 20);
     textView2.setPadding(20, 20, 20, 20);
     textView3.setPadding(20, 20, 20, 20);
     tableRow.addView(textView1);
     tableRow.addView(textView2);
     tableRow.addView(textView3);
     tableLayout.addView(tableRow);
     c.moveToNext() ;
 }
 setContentView(tableLayout);
 db.close();
}
public void close(View view)
{
System.exit(0); 
}

Answer 1

更新

SQLiteDatabase db = this.getWritableDatabase();
ContentValues values = new ContentValues();
values.put(KEY_TODO, todo.getNote());
values.put(KEY_STATUS, todo.getStatus());

// updating row
return db.update(TABLE_TODO, values, KEY_ID + " = ?",
        new String[] { String.valueOf(todo.getId()) });`

删除

public void deleteToDo(long tado_id) {
SQLiteDatabase db = this.getWritableDatabase();
db.delete(TABLE_TODO, KEY_ID + " = ?",
        new String[] { String.valueOf(tado_id) });

}

详细研究请找到链接 android-sqlite-database-with-multiple-tables

Answer 2

您可以使用

"DELETE * FROM Student WHERE fname LIKE %"+fname_variable+"% OR lname LIKE %"+lname_variable+"% OR email LIKE %"+email_variable+"%;"

用于删除，如果要更新fname

"UPDATE Student SET fname="+new_fname_var+" WHERE fname="+old_fname_var+";"

希望它有所帮助。：）

参考：http://www.w3schools.com/sql/sql_update.asp。

Answer 3

看一下本教程：

http://www.androidhive.info/2011/11/android-sqlite-database-tutorial/

更新数据库中的记录，请使用此

    dbName.update (String table, ContentValues values, String whereClause, String[] whereArgs)

删除和更新数据库

3 个答案: