Function created with compilation error in PLSQL - oracle

Question

When I compile the below code I am getting a error message "Function created with compilation errors"
create or replace function find_port(ip_ID in int) RETURN int
is
t_count number;
count varchar;
begin
select is_rail into count from table where id = ip_ID;
case
when count ='True' then t_count:=1;
when count ='False' then t_count:=0;
end case;
end;
/

Answer 1

i am getting a error message "Function created with compilation errors"
So the question you should be asking is, "how do I get a list of compilation errors for my PL/SQL code?"
Other people have told you how to fix the current errors in your code, but the more important skill is that you find out how to diagnose your code for yourself.
Oracle is a database, and it stores metadata in a set of special views called the data dictionary. These views include views for compilation errors. This query will work in any SQL environments:
select name, type, line, text -- or just *, obvs
from user_errors ue
order by ue.name, ue.type, ue.sequence;
There are also ALL_ERRORS and DBA_ERRORS views. Find out more.
In SQL*Plus you can run sho err (short for show errors). IDEs like PL/SQL Developer or Oracle SQL Developer will show compilation errors automatically.
Once you know how to get the text of the errors you need to know that LINE will tell you the line where the error is raised. Although with certain classes of error (such as missing commas or unmatched brackets) the indicated line may not be the line where the actual error resides. Unfortunately there is still a need for interpretation and understanding, which requires experience.

Answer 2

Actually, COUNT can be used as a PL/SQL variable:
SQL> create or replace function f_test return int is
2 count number;
3 begin
4 select 1 into count from dual;
5 return 2;
6 end;
7 /
Function created.
SQL> select f_test from dual;
F_TEST
----------
2
SQL>
However, you can't return it:
SQL> create or replace function f_test return int is
2 count number;
3 begin
4 select 1 into count from dual;
5 return count;
6 end;
7 /
Warning: Function created with compilation errors.
SQL> show err
Errors for FUNCTION F_TEST:
LINE/COL ERROR
-------- -----------------------------------------------------------------
5/3 PL/SQL: Statement ignored
5/10 PLS-00204: function or pseudo-column 'COUNT' may be used inside a
SQL statement only
SQL>
Here, #priya, you can see how to help yourself - SHOW ERR will tell you what's wrong with your code.
Apart from that, CASE statement you used was invalidly written; should have been similar to this:
SQL> create or replace function f_test return int is
2 l_count number;
3 t_count number;
4 begin
5 select 1 into l_count from dual;
6
7 t_count := case when l_count = 1 then 1
8 when l_count = 2 then 2
9 end;
10
11 return t_count;
12 end;
13 /
Function created.
SQL> select f_test from dual;
F_TEST
----------
1
SQL>

Answer 3

count is a SQL function and thus not a better choice to be used as a PL/SQL variable. The CASE block can be used within the select statement.
Furthermore, your function does not RETURN any value.
create or replace function find_port(ip_ID in int) RETURN int
is
t_count number;
begin
select case
when is_rail = 'True' then 1
when is_rail = 'False' then 0
end into t_count from yourtable where id=ip_ID;
RETURN t_count;
end;