Question

I would like to query a table, where i need 2 columns meet certain criteria, as an example, a table like below:

LastName FirstName Age address
LN1      FN1        18  ADD1
LN2      FN1        20  ADD2

Now I want to extract 1st address like below:

select * from mytable
where LastName in 'LN1' and FirstName in 'FN1'

Can I use such a condition:

where (LastName, FirstName) in (LN1,FN1)

please kindly help. thanks.

Answer 1

Some databases support the syntax you want:

where (LastName, FirstName) in ('LN1', 'FN1')

Note that the single quotes are important, because they are string constants.

In other databases, you need to do:

where LastName = 'LN1' or FirstName = 'FN1'

or perhaps put the constants into a derived table, and use a join for the matching.

Answer 2

You can either use or or and

select * from mytable where LastName = 'LN1' or FirstName = 'FN1';
select * from mytable where LastName = 'LN1' and FirstName = 'FN1';