Sql count distinct values based on column

Question

I need an help about a sql query. I have a table as the following

error   session
error1     1 
error1     1
error2     1
error1     2
error1     2
error2     2

I have to count errors once related to session. The result should be

error   number of errors     
error1         2
error2         2

Thank you

Edit your question and provide sample data and expected results for that data. This question probably has many duplicates, but it's difficult to be sure because your question is so unclear. — Disillusioned
– Disillusioned, Commented May 25, 2017 at 7:16

India.Rocket · Accepted Answer · 2017-05-25 07:19:28Z

4

Use aggregated function count and group by to do this.

Try this:-

Select error, count(distinct session) as number_of_errors
from
your_table_name
group by error

answered May 25, 2017 at 7:19

India.Rocket

1,2451 gold badge8 silver badges11 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Stefano Zanini · Accepted Answer · 2017-05-25 07:19:56Z

1

You have to group by the error and count the distinct sessions, and you can do that pretty much repeating these words in a query

select  error, count(distinct session)
from    yourTable
group by error

answered May 25, 2017 at 7:19

Stefano Zanini

5,9362 gold badges16 silver badges33 bronze badges