When merging 2 tables on a common by-variable you run the risk of having a different length on this (or these) by variable(s). If this is the case, SAS will casually inform you with the following warning:
WARNING: Multiple lengths were specified for the BY variable mergevar by input data...
Reduce hard coding by using the VCOLUMN table in SASHELP to get a list of your variables into a macro variable array
Very often it is useful to have a list of all the variables you have in a certain table. You don’t always want to type them out yourself (hard coding) but instead want an...