Formatting a Text Process Variable to use in a "where" clause SQL

Hi! I have created a process model in which the user can add new rows. 

I´m saving the value of the different materials (pv!Record....material) in a process Variable ("MaterialesDefi")

In this pick, you can see the value adquired and saved in the process variable. In this case: zz;vv

The fact is that I want to use this materials in a WHERE clause (SQL syntax),and it is not working. Even though I tried to use a function like SUBSTITUTE() when assigning the value, trying to substitute the ; for the ",", the result of the pv is always the same

I know that to use it in a where clause, I must use the operator "in" and also the string should be (string1,string2). But I haven´t managed to do so, the value of the pv! remains like untouchable

What can I do?