Unpivot data

Hi,
I have table a
Id  class1
123. 001
123. 002

Then table B

Id. Class1 class2 class3

123.    002. 001 002

Table b has like 50 class1 till class 50

I don’t want to do or query is it easy way to join two tables and see if table a column1 data is in table b column 1 to 49.