In SQL Server Management Studio 2012, I run this query:
SELECT * FROM Contacts
This query successfully executes in approximately 44 seconds.
SELECT * FROM Contacts WHERE FirsttName = 'David"
This query successfully executes in approximately 0 seconds. So I guess my question is what is happening that causes these query times to be so different. From my admittedly naive perspective, I would think that in both cases all table rows would need to be surveyed to check if FirstName is equal to 'David', and that the condition should not have that large of an effect. In reality, I assumed that the query would take a little longer, because of the additional check.
Another example is:
SELECT * FROM Jobs
successfully executes in approximately 25 seconds.
SELECT * FROM Jobs WHERE JobName = "Sales"
successfully executes in approximately 0 seconds.
This is not a life-threatening/blocking/oh my god why can't I solve this problem issue. Just something that makes me wonder.