Question

I have a database table that stores error messages, and I want to run various queries on them. First, I get an overall count by grouping them like this:

select MessageText, COUNT(*) from MessageLog group by MessageText

And the result is:

1  Input string was not in a correct format      4
2  Value cannot be null. Parameter name: Int     8 
3  Value cannot be null. Parameter name: String  1

Now, if I try to select messages by the text string, some of them return no results even though the messages exist. For example,

select * from MessageLog where MessageText = 'Value cannot be null. Parameter name: Int'

does not return any results, even though the previous query shows there are 8 of them. What is it about this string that fails to match?

Answer 1

My guess is that you either have white spaces in your MessageText that you are not accounting for or you are doing something you are not showing us. I ran the following query:

with MessageLog as
(
    select 1 as id, 'Input string was not in a correct format' as MessageText, 4 as count
    UNION 
    select 2 as id, 'Value cannot be null. Parameter name: Int' , 8
    UNION
    select 3 as id, 'Value cannot be null. Parameter name: String' , 1
)
select * from MessageLog where MessageText = 'Value cannot be null. Parameter name: Int'

and got the expected results.