How to append '0' to the left of a string in a query under a certain condition?

Question

SQL

There is a table with phone numbers. Some of the 5 characters, and others of 4. It is necessary to attach 0 to those of 4 at the beginning. Here I am looking for ways to do this. I can do it through the cursor, sorting through each line, but I thought maybe somehow I could get out of it through one UPDATE? Or something else optimally and beautifully.

Answer 1

just for the general case,
not only 4 digits, but also 3, 2 .. to the form 00XYZ
UPDATE Table SET
field = RIGHT('00000' + CAST( field AS varchar(5)), 5)
WHERE LEN(field) <= 5