Optional sql query where param

I have an optional parameter in my sql query.   How do i code the "where" statement in the query to (1) when the optional parameter is filled in to use it,  and when its blank or null pull "everything"
example:

where student = parm1 else student = <pull all students>
Mike JohnsonBusiness Inteligence DeveloperAsked:
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Guy Hengel [angelIII / a3]Billing EngineerCommented:
where ( student = parm1 or param1 is null )
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fsouzabrasilCommented:
where ( student = parm1 or param1 is null or param1='' )
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shru_0409Commented:
where student = decode (student,parm1,parm1, student)

try this
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awking00Information Technology SpecialistCommented:
Is this part of a procedure? If so, can you post it?
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BrightApolloCommented:
There's always

WHERE student LIKE parm1

Assuming you set the parm1 default to the wildcard for your db, any valid input overwrites the wildcard.  Otherwise, you get everything.

--#

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awking00Information Technology SpecialistCommented:
where student like nvl(param1, student)
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uaexpertCommented:
It seems this question is not concerned to SQL.
You just need to provide user-friendly query builder in your program. If user add some condition(s) - that builder will create necessary SQL statement if not - you can use some "default" statement (SELECT * FROM Sometable).
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BrightApolloCommented:
awking00 had the better solution, in my professional opinion.  it stands alone, it's extremely simple and compact, and requires no OR logic.  So, I object to the points split.  I really think awking00 has it.
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awking00Information Technology SpecialistCommented:
BrightApollo,
Thanks for your support. The only problem I see is that this is an Oracle solution and an awful lot of questioners use this zone (annoyingly so) when they're working with another RDBMS. Even so, I'm sure there is corresponding syntax (e.g. IFNULL) in other databases that could be applied. The points aren't that important to me. I just want to see questioner's problems resolved and wish that they would acknowledge the same.
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BrightApolloCommented:
Given the context of the forum, you provided an optimal Oracle solution.  I understand the greater context of the problem, but "SQL syntax" is the appropriate vendor-neutral forum.  I just wanted to stipulate it for the record, in the event someone looks at the thread and actually wants the Oracle solution.
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