Add index column with if statement

[joooffice]

I currently add an index column that pulls the starting figure from the results of another query called Last Submission ID which works fine.

= Table.AddIndexColumn(#"Sorted Rows", "Index", #"Last Submission ID"+1, 1)

Sometimes the value for #Last Submission ID = null and so it causes an error. When it is null the index should just start at 1

I've tried  

= Table.AddIndexColumn(#"Sorted Rows", "Index", if #"Last Submission ID<>null then #"Last Submission ID"+1 else 1, 1)

but it doesnt work. I probably have the syntax wrong. 

[CNENFRNL · Accepted solution]

@joooffice , you might want to try

= Table.AddIndexColumn(#"Sorted Rows", "Index", (#"Last Submission ID"??0)+1, 1)