As a note, I'd analyze why you're doing this and whether you really need it. You should be able to select the different combination of picklist values in reports/list view filters.
Either way, you can do either of these two things - but #1 is the option I would use.
Reference
- Concatenate the string based on the IF statements
IF(ISPICKVAL(SAQ_Required__c , 'yes'), 'SAQ ', '') &
IF(ISPICKVAL(LUA_Required__c , 'yes'), 'LUA ', '') &
IF(ISPICKVAL(Construction_Required__c, 'yes'), 'Construction', '')
- You could also utilize
AND
to evaluate multiple requirements and catch all the possibilities. This is much more cumbersome and would get out of hand quickly with more values.
IF(
AND(
ISPICKVAL(SAQ_Required__c, 'yes'),
ISPICKVAL(LUA_Required__c, 'yes'),
ISPICKVAL(Construction_Required__c, 'yes')), 'SAQ LUA CONSTRUCTION',
IF(
AND(
ISPICKVAL(SAQ_Required__c, 'yes'),
ISPICKVAL(LUA_Required__c, 'yes')), 'SAQ LUA',
IF(
AND(
ISPICKVAL(SAQ_Required__c, 'yes'),
ISPICKVAL(Construction_Required__c, 'yes')), 'SAQ CONSTRUCTION',
IF(
AND(
ISPICKVAL(LUA_Required__c, 'yes'),
ISPICKVAL(Construction_Required__c, 'yes')), 'LUA CONSTRUCTION', '')
)))