Customize your Microsoft Access queries by adding expressions to your fields. Expressions calculate information and display the result in the query’s datasheet view or any object that relies on that query. Once you add an expression, that field can’t be updated, so it’s best to use expression fields in combination with input fields. With expressions you can automate calculations and speed up database processes. If you need to add leading zeros to a text field, you can do so with an expression. Tips Writer Bio

How to Add Leading Zeros in a Text Field in Microsoft Access - 30