Handeling NULL Variable

Good afternoon,

I'd like to like how you guys handle a situation like the one I'm going to describe in just a moment. I'm pretty sure I'm not handeling it in the best way, so I'll just try to explain the situation and learn something from the gurus.

Let's imagin I have the following tables:[Companies]
Id [Uniqueidentifier] [PK]
Alias [NVarChar]
Status [Bit]

[Campanies_JobTitles]
Id [PK]
CompanyId [Uniqueidentifier]
Alias [NVarChar]
Status [Bit] If I want to know the job titles of company 1 I could easely set the following stored procedure: SELECT
JT.Id AS Id
,JT.Alias AS Alias
FROM
Companies_JobTitles JT
WHERE
JT.Status = 1
AND JT.CompanyId = @CompanyId
ORDER BY
JT.Alias ASC;

Now, if the user wants to list the job titles across all the companies I could pass a special value and identify that, as follows:IF (@CompanyId IS NOT NULL)
BEGIN
SELECT
JT.Id AS Id
,JT.Alias AS Alias
FROM
Companies_JobTitles JT
WHERE
JT.Status = 1
AND JT.CompanyId = @CompanyId
ORDER BY
JT.Alias ASC;
END
ELSE
BEGIN
SELECT
JT.Id AS Id
,JT.Alias AS Alias
FROM
Companies_JobTitles JT
WHERE
JT.Status = 1
ORDER BY
JT.Alias ASC;
END

 This works fine. I just find it a bit counter productive to copy paste the query and wrap it into an if statement. So, the bottom line is: how can I do this in a more "professional" way?

Best regards.