A family of Microsoft relational database management systems designed for ease of use.
You have two options:
1. With a column (field) of number data type, format the column as 00000. This will display the zip code as five digits with leading zeros where necessary, but the actual value will be numeric.
2. With a column of short text data type, the value will be whatever is entered, including any leading zeros. If you change the data type of the column from number to short text, you can then add leading zeros to all existing values where necessary by executing the following UPDATE query:
UPDATE [NameOfTableGoesHere]
SET [NameOfZipCodeColumnGoesHere] = FORMAT([NameOfZipCodeColumnGoesHere], "00000");
The value will now be a string expression which includes the leading zeros.