我试图找出如何一次删除一个用户的方法,方法是在edittext中键入用户名,然后单击删除,然后从中删除所有用户信息(用户名,用户编号,密码,生日,电话,地址)数据库。下面是我的代码,由于某种原因它不起作用,任何人都可以帮助我!我非常绝望,我花了好几个小时试图找出问题所在。
DatabaseHelperUser类:
public class DatabaseHelperUser extends SQLiteOpenHelper {
public static final String DATABASE_NAME = "User.db";
public static final String TABLE_NAME = "User_table";
public static final String COL1 = "ID";
public static final String COL2 = "UserNum";
public static final String COL3 = "UserName";
public static final String COL4 = "Password";
public static final String COL5 = "BirthDate";
public static final String COL6 = "Phone";
public static final String COL7 = "Address";
public DatabaseHelperUser(Context context) {
super(context, DATABASE_NAME, null, 1);
}
@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL("create table " + TABLE_NAME + " (ID INTEGER PRIMARY KEY AUTOINCREMENT, UserNum TEXT,UserName Text,Password Text,BirthDate Text,Phone Text,Address Text)");
}
@Override
public void onUpgrade(SQLiteDatabase db, int i, int i1) {
db.execSQL("DROP TABLE IF EXISTS " + TABLE_NAME);
onCreate(db);
}
public Cursor getData() {
SQLiteDatabase db = this.getWritableDatabase();
Cursor res = db.rawQuery("select * from " + TABLE_NAME, null);
return res;
}
public boolean deleteData(String UserName) {
SQLiteDatabase db = this.getWritableDatabase();
return db.delete(TABLE_NAME, "UserName" + "=?" + UserName, null) > 0;
}
}
RemoveUser类:
public class RemoveUser extends AppCompatActivity {
Button btdelete;
EditText txtUser;
DatabaseHelperUser myDb;
private String selectedName;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_remove_user);
btdelete = (Button) findViewById(R.id.butRemove);
txtUser = (EditText) findViewById(R.id.etxtUserName);
myDb = new DatabaseHelperUser(this);
btdelete.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
boolean delete = myDb.deleteData(txtUser.getText().toString());
if(delete == true)
Toast.makeText(RemoveUser.this,"User has been deleted", Toast.LENGTH_LONG).show();
else
Toast.makeText(RemoveUser.this,"User has not been deleted", Toast.LENGTH_LONG).show();
}
});
}
}
您必须将变量UserName
作为方法的3d参数传递delete()
,以便?
在执行语句时它将替换占位符:
public boolean deleteData(String UserName) {
SQLiteDatabase db = this.getWritableDatabase();
return db.delete(TABLE_NAME, "UserName = ?", new String[] {UserName}) > 0;
}
本文收集自互联网,转载请注明来源。
如有侵权,请联系 [email protected] 删除。
我来说两句