Question: I need to store an CARD ID number in Database. So there is no calculation just a search of the ID and putting the value in Session as property in a class.

The is ID is always numeric and it's 12 positions.
e.g. 123456789012 and I would like to show on the screen in this format. 123.456.789.012 (every 3 digit a dot).

I tried a test and defined Decimal(12,0) in database and I have put this value in database: 555666777888

then I try to display on the screen I used this code (CardID is decimal):

```
  lblCardID.Text = ent.CardID.ToString("0:#,###")

```

but it shows on the screen like this: **555,666,77:7,888** 

where is the **colon (:)** coming from? 

question additional:
- What type shall use in MS SQL to store this value in Database. Decimal (12,0) or Nvarchar(12) ?

Answer: 
`nvarchar` is definitely not needed. if it's always 12 digits, `char(12)` would be fine, but I think a 64-bit integer would be most appropriate.
If you need to store the formatting, and it's just a numeric value, use varchar, don't waste time with nvarchar as it increases your storage size and won't do you any good unless you expect special (international) chars