if i have two strings in mysql:

@a="Welcome to Stack Overflow"
@b=" Hello to stack overflow";

is there a way to get the similarity percentage between those two string using MYSQL? here for example 3 words are similar and thus the similarity should be something like:
count(similar words between @a and @b) / (count(@a)+count(@b) - count(intersection))
and thus the result is 3/(4 + 4 - 3)= 0.6
any idea is highly appreciated!

mysql similarity
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