SQL query: group and count distinct values

Question

Given this DB table:

A_column       B_column
---------------
A1      1
A1      2
A1      2

A2      1
A2      1
A2      1

A3      2
A3      3
A3      4
A3      5

How do I write SQL SELECT query to print out number of unique values in B_column per value in A_column, so output would be like this:

A1     2
A2     1
A3     4

I tried this, but doesn't seem to work properly:

SELECT A_column, count(B_column) FROM table GROUP BY A_column

GMB · Accepted Answer · 2020-10-08 08:03:27Z

2

Use distinct:

SELECT A_column, count(distinct B_column) FROM table GROUP BY A_column

answered Oct 8, 2020 at 8:03

GMB

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