Phpcms How to write a sentence like this

Want to define the CATID in the SQL sentence
If Num=1 so catid=5, otherwise catid=7
I don't know how to write such a sentence.
Here is the SQL sentence,
{pc:get sql= "select * from category where category.catid= $catid order by catid ASC" num= "7" return= "Data"}
Note that the sentence I want to write is put in front of the SQL sentence

Reply to discussion (solution)

Is it OK to add an if statement in front of you?
If $num ==1
{pc:get sql= "select * from category where category.catid=5 order by catid ASC" num= "1" return= "Data"}
Else
{pc:get sql= "select * from category where category.catid= $catid order by catid ASC" num= "7" return= "Data"}

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