我想搜索我的數據庫中的用戶名重複安卓

Question

Cursor c=db.rawQuery("Select orders from table_name where usrname=username;",null); 

usrname是在edittext中輸入的字符串，用戶名已經存在於數據庫中。

if(c!=null) 
{ 
    Toast.makeText(this,"Username already exists,please use a different username",Toast.LENGTH_SHORT).show(); 
} 

Answer 1

變化的條件

if(c.getCount()>0) { 
Toast.makeText(this,"Username already exists,please use a different username",Toast.LENGTH_SHORT).show(); 
} 

Answer 2

Cursor c=db.rawQuery("Select orders from table_name where usrname=yourusername",null); 
if(c.getcount>0) 
{ 
    Toast.makeText(this,"Username already exists,please use a different username",Toast.LENGTH_SHORT).show(); 
}