How to transfer an AWK matching string with Parameters

How to transmit the common Linux technology-Linux technology and application information through passing in the AWK matching string with parameters is as follows. Num1 = 'awk'/1. SQL/{print $1} '2. SQL 'is the first word to query 2. the SQL file contains the string 1. SQL
If I want to pass in 1. SQL parameters, for example:
File_name = 1. SQL
Num1 = 'awk'/$ file_name/{print $1} '2. SQL'
Why is this incorrect? How should I write string matching parameters here? Could you please take a look? Thank you