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TABLE

Col1 Col2 Col3 a 1 Z a 2 Z a null empty b 1 Z b 2 X b 3 Y b 3 Y

I want to know the count of distinct values by column.

  • Col1 count = 2
  • Col2 count = 3 (or 4 uncertain null handling)
  • Col3 count = 3 (or 4 uncertain empty handling)

I have been attempting different counting and grouping clauses, but this may be not the way.

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    This would look like SELECT COUNT(DISTINCT col1), COUNT(DISTINCT col2), COUNT(DISTINCT col3) FROM yourtable Commented Aug 3, 2023 at 20:27
  • This is not a duplicate. Appreciate the syntax given in comment and answer. Commented Aug 3, 2023 at 22:07
  • 1
    What about it is not a duplicate? The accepted answer is the same as the duplicate answer? Commented Aug 3, 2023 at 22:33

1 Answer 1

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3

count(distinct ...) should do the trick

Example

Declare @YourTable Table ([Col1] varchar(50),[Col2] int,[Col3] varchar(50)) Insert Into @YourTable Values ('a',1,'Z') ,('a',2,'Z') ,('a',null,'') -- Note the empty string ,('b',1,'Z') ,('b',2,'X') ,('b',3,'Y') ,('b',3,'Y') Select Col1 = count(distinct col1) ,Col2 = count(distinct col2) ,Col3 = count(distinct nullif(col3,'')) -- Remove NullIf() if you want to count empty strings From @YourTable

Results

Col1 Col2 Col3 2 3 3
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2 Comments

count(distinct nullif(col3,'')) is going to be a little inefficient as it cannot use indexes. Might be better to do count(distinct col3) - iif(count(case when col3 = '' then 1 end) > 0, -1, 0)
@Charlieface. Just illustrating a method to exclude empty strings. Personally, an empty string is a value. I also I would have to benchmark your suggestions to be convinced

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