Differences between varchar and nvarchar in SQL Server

The broad range of data types in SQL Server can sometimes throw people through a loop, especially when the data types seem to be highly interchangeable. Two in particular that constantly spark questions are VARCHAR and NVARCHAR: what's the difference between the two, and how important is the difference?

VARCHAR is an abbreviation for variable-length character string. It's a string of text characters that can be as large as the page size for the database table holding the column in question. The size for a table page is 8,196 bytes, and no one row in a table can be more than 8,060 characters. This in turn limits the maximum size of a VARCHAR to 8,000 bytes.

The "N" in NVARCHAR means uNicode. Essentially, NVARCHAR is nothing more than a VARCHAR that supports two-byte characters. The most common use for this sort of thing is to store character data that is a mixture of English and non-English symbols — in my case, English and Japanese.

The key difference between the two data types is how they're stored. VARCHAR is stored as regular 8-bit data. But NVARCHAR strings are stored in the database as UTF-16 — 16 bits or two bytes per character, all the time — and convert

Export to Excel with proper fomatting:

Hope from above example now one can easily export data from GridView. But an important concern is to setthe formatting to the target file. In this reagard mso-number-format ease our life. Lets we need todisplay date & time in the GridView but we wants short date format when exporting. To do the one can use mso-number-format in the following way. Modify your export button click event by the following code segment.

string datestyle = @"<style>.date { mso-number-format:'Short Date'; }</style>";
foreach(GridViewRow oItem in gvEdit.Rows)
oItem.Cells[4].Attributes.Add("class","date");
Response.Clear();
Response.AddHeader("content-disposition", "attachment; filename=SupplierList.xls");
Response.ContentType = "application/vnd.xls";
System.IO.StringWriter WriteItem = new System.IO.StringWriter();
System.Web.UI.HtmlTextWriter htmlText = new HtmlTextWriter(WriteItem);
Response.Write(datestyle);
gvEdit.RenderControl(htmlText);
Response.Write(WriteItem.ToString());
Response.End();
-------------------------------------




List of some useful mso-number-format:

Format	Description
mso-number-format:"0"	NO Decimals
mso-number-format:"0\.000"	3 Decimals
mso-number-format:"\#\,\#\#0\.000	Comma with 3 dec
mso-number-format:"mm\/dd\/yy"	Date7
mso-number-format:"mmmm\ d\,\ yyyy"	Date9
mso-number-format:"m\/d\/yy\ h\:mm\ AM\/PM"	Date -Time AMPM
mso-number-format:"Short Date"	04/07/2008
mso-number-format:"Medium Date"	04-Jun-08
mso-number-format:"d\-mmm\-yyyy"	04-Jun-2008
mso-number-format:"Short Time"	4:49
mso-number-format:"Medium Time"	4:49 am
mso-number-format:"Long Time"	4:49:13:00
mso-number-format:"Percent"	Percent with two dec.
mso-number-format:"0%"	Percent with no dec.
mso-number-format:"0\.E+00"	Scientific Notation
mso-number-format:"\@"	Text
mso-number-format:"\#\ ???/???"	Fractions up to 3 digits
mso-number-format:"\0022£\0022\#\,\#\#0\.00"	£10.52
mso-number-format:"0\.0000";font-weight:700;	4 dec.+multiple format

Note:
If you do not find your required format from above list then try creating a spreadsheet with a single cell entry according to your required format. Then from file menu select the 'Save as Web Page' option to create a html file. Read & examine the code for this and findout the mso-number-format from the style declarations.