Variable not set by choice

Question

I have a problem when the variable does not receive the select job.

The selection joins the @contracts table variable (which is used to control the loop), and then joins the actual contract and contract row tables.

my choice:

select top 1 
        @contract_id = c.contract_id 
        , @account = ch.account
        , @service = cl.service
        , @model = cl.model
        , @serial = cl.serial
        , @contract = ch.contract
    from 
        @contracts c
        inner join contractline cl on c.contract_id = cl.contract_id
        inner join contractheader ch on cl.contract = ch.contract
    where
        cl.contract_id = @contract_id

But when I do select @contract_id, I can return NULL, like all my variables.

I did a simple select * from @contracts c inner join contractline cl on c.contract_id = cl.contract_id inner join contractheader ch on cl.contract = ch.contractone and this returns exactly 1 row with values ​​in all the right places, without zeros in the selected values.

What did I do wrong?

Answer 1

, WHERE . , SELECT , WHERE - .

SELECT WHERE (, NULL) . , .

Answer 2

@contract_id select, where. , @contract_id null?