Better way to check unique data in RDBMS database tables

[SOHELAHMED7]

lets say a table dogs have column comment and it contains data such as

id	comment
1	red fox
2	Red Fox
3	red fox
4	red fox
5	red-fox
6	red_fox
7	Red-Fox

and so on

and task is to get unique comments

Generally we use SQL select distinct comment from dogs but most time we are mistaken

we dont want to check strictly all spaces, hyphen underscore etc

and want to check simple unique of red dog ness in comment col

[SOHELAHMED7]

Solution :