In all other DBMS, the variable names have a distinctive character to differentiate between variables and column names:
Example:
SQL Server uses @
MySql uses ?
Oracle uses :
Firebirdsql uses :
It makes it easier to write and manage queries especially in stored procedures.
Just compare the below:
create stored procedure get_user_for_editing(user_id int, out username varchar)
begin
select username into @username from users where user_id = @user_id;
end;
to this mess:
create stored procedure get_user_for_editing(user_id int, out username varchar) begin
select u.username into get_user_for_editing.username from users u where get_user_for_editing.user_id = get_user_for_editing.user_id;
end;
Prefixing the variables (ex: p_user_id) makes the application code harder to write as we have a lot of dynamic code that is expecting "user_id" instead of "p_user_id".
Is there any plan to add a character to differentiate between variables?
No, and I don't think so it is necessary in this moment (so I am against a introduction new prefix)
a) PostgreSQL safely solves conflicts between plpgsql and SQL - what Oracle doesn't
b) Usual prefix for plpgsql variables is "_" - I don't see a difference between @,?,: