File grep for specific column

Question

How to search each line in first file against a specific column in a second comma separated file so that whole line in the first file matches the whole column in the second file.

grep -Ff file1 file2 , will search the entire line in the second file, but i want to search on a specific column.

Eg.

file1.txt

20
300

file2.txt

200,10
220,2
300,5

I want the result to only match 300,5 and not the first 2 rows.

Answer 1

$ awk -F, 'NR==FNR{a[$1]; next} $1 in a' file{1,2}

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