How can I set a special format in a column or leave the field blank

Question

I have a column that is called APC Standard. In this column I want to set the following format APCxxxx (APC + 4 numbers). I also want to have the possibility to leave the column blank.

I have already found the formula for the desired format.

=IF(AND(LEN([APC Standard])=7,LEFT([APC Standard],3)="APC",ISNUMBER(0+RIGHT([APC Standard],4))),TRUE,FALSE)

However, I cannot find a way to leave the column blank.

Can someone please help me?

Answer 1

If you have already found the formula for your desired format, you can use below to check if the column is blank or not:

=IF(ISBLANK([APC Standard]), TRUE, IF(AND(LEN([APC Standard]) = 7, LEFT([APC Standard], 3) = "APC", ISNUMBER(0 + RIGHT([APC Standard], 4))), TRUE, FALSE))

Reference:

1. Calculated Field Formulas
2. IS functions - ISBLANK