I have data in my sql database like 645.000
and i need to format it to include currency symbols e.g., $645.000
How can I achieve this in SQL?>
You don't need to and should not be formatting it in SQL Server - instead it's your application that needs to format it for the UI.
You didn't say what your application is coded in, e.g. in C# we could use
Label1.Text = string.Format("Amount is {0:c}", amount);
Then you can be sure that not only will it use the correct currency symbol, it will also use the correct decimal and thousands separator symbols.