Why does Execute Immediate throw this PLS-00201 error? - sql

Question

I was trying to run the following code and it failed in the execute immediate block. So, am I going wrong with the syntax?
DECLARE
l_data long;
emp_rec EMP%rowtype;
begin
select * INTO emp_rec from EMP A WHERE A.EMP_NO = '001322';
for x in ( select column_name, data_type
from user_tab_columns
where table_name = 'EMP' )
loop
execute immediate
'begin
:x := emp_rec.' || x.column_name || ';
end;' using OUT l_data;
dbms_output.put_line( x.column_name || ' = ' || l_data );
end loop;
end;
I get this error
PLS-00201: Identifier EMP_REC.EMP_NO must be declared

Answer 1

Your emp_rec variable is a local PL/SQL record. When you do this, even with a static field name reference:
execute immediate 'begin :x := emp_rec.emp_no; end;'
the dynamic SQL runs in a separate context to the block that calls it. You then run a new anonymous PL/SQL block within that context.
Any variables from your outer anonymous block, specifically emp_rec here, are out of scope to the dynamic SQL context. They just do not exist to the code that is trying to assign the value to :x.
You could possibly do something with dbms_sql to make this dynamic, but if you know the table columns it would be easier to do:
declare
l_data varchar2(4000); -- long is deprecated; how big does this really need to be?
emp_rec EMP%rowtype;
begin
select * INTO emp_rec from EMP A WHERE A.EMP_NO = '001322';
for x in (
select column_name, data_type
from user_tab_columns
where table_name = 'EMP'
)
loop
case x.column_name
when 'EMP_NO' then
l_data := emp_rec.emp_no;
-- when clauses for each column in your real table
when 'FIRST_NAME' then
l_data := emp_rec.first_name;
when 'LAST_NAME' then
l_data := emp_rec.last_name;
-- list other columns and assignments
-- else ...
end case;
dbms_output.put_line( x.column_name || ' = ' || l_data );
end loop;
end;
/
although as #APC pointed out, the loop is now a bit pointless, since you can just do:
declare
emp_rec EMP%rowtype;
begin
select * INTO emp_rec from EMP A WHERE A.EMP_NO = '001322';
dbms_output.put_line( 'EMP_NO = ' || emp_rec.emp_no );
dbms_output.put_line( 'FIRST_NAME = ' || emp_rec.first_anme );
dbms_output.put_line( 'LAST_NAME = ' || emp_rec.last_name );
-- ... any other columns you want to show
end;
/

Answer 2

The emp_rec in the EXECUTE IMMEDIATE statement exists in a different namespace from the emp_rec in the calling code.
Not sure exactly what you're trying to achieve but it might be something like this:
DECLARE
l_data long;
emp_rec EMP%rowtype;
begin
select * INTO emp_rec from EMP A WHERE A.EMP_NO = '001322';
for x in ( select column_name, data_type
from user_tab_columns
where table_name = 'EMP' )
loop
execute immediate
'declare
lrec EMP%rowtype;
begin
lrec := :emp_rec;
:x := lrec.' || x.column_name || ';
end;' using emp_rec, OUT l_data;
dbms_output.put_line( x.column_name || ' = ' || l_data );
end loop;
end;
Note: I tested a version of this code in 12C and it does work there. Alas it doesn't work in 11gR2 (and presumably earlier versions too); it hurls PLS-00457. Still, 11gR2 is pretty much out of support except for folks with deep pockets, everybody ought to be using 12c by now:)

Answer 3

My guess would be that you have a hidden column in your emp table. Those are columns that've been marked as unused but not yet dropped, and as such, they are not available to be selected from.
You could update your cursor to use:
select column_name, data_type
from user_tab_cols
where table_name = 'EMP'
and hidden_column != 'NO'
or:
select column_name, data_type
from user_tab_columns
where table_name = 'EMP';
Note the different view name used in both queries - user_tab_columns doesn't output rows for hidden columns, whereas user_tab_cols does so you have to explicitly filter them out if you don't want to see them.