[SQL] Want to declare a string array variable? Declare a table variable instead.

Sometimes we want to declare a array to represent the condition of WHERE IN.
But you can not declare a array in SQL, instead, you can try to declare a table variable with the value you want to put in.

DECLARE @usernameArray TABLE (username varchar(50))
INSERT INTO @usernameArray VALUES ('M12345'), ('M12346'), ('M12347'), ('M12348'), ('M12349')

SELECT * FROM member_info m WHERE  m.username IN 
(SELECT username FROM @usernameArray)

In the code block, I declared a table variable, and inserted 5 rows into the variable.
Then when I needed to select with the condition.
I selected the array from the table variable we declared before (@usernameArray).