php - Preventing duplicates when allowing user to populate SQL database -

so looking have survey answers populated sql database. 1 problem not sure how avoid allowing duplicates database.

for example, want user tell organization representing.

say 1 user enters "big brothers , big sisters" , another, same organization enters "big brothers & big sisters". have separate organization table these answers populated into. how prevent creating 2 separate rows? there several instances of fill in blank questions foresee problem occurring with.

you might try utilizing levenshtein algorithm ( https://en.wikibooks.org/wiki/algorithm_implementation/strings/levenshtein_distance ) , languages (such php) have methods utilize built in. in addition, you'll have build permutations of input string using common substitutions (& / and) , try validating permutations against database make sure doesn't exist.

for it's worth, might ui decision present user similar options make sure did or didn't mean type in did.

sorry if it's not help; not sure total requirements are. hope helps!