Can someone help me find the error in this procedure? - oracle

Question

I would like to know where is the mistake in this procedure
set serveroutput on
create or replace procedure insert_table(column_name in varchar2, dat in varchar2)
as
table_name varchar2(100):= column_name || '_' || dat;
sql_create varchar2(100) := 'create table '||table_name||'(FIRSTNAME varchar2(100))';
sql_str varchar2(100);
CURSOR c_emp is
select FIRSTNAME
from employees
where column_name = dat;
begin
execute immediate sql_create;
for r_reg in c_emp
loop
sql_str:='INSERT INTO '||table_name||'('''||r_reg.firstname||''')';
execute immediate sql_str;
end loop;
end;
/
execute insert_table('CITY','London');
Edit:
Ok i add the correction mentioned below in the syntax error, but how can I do so that the parameter of the column name can be taken at the cursor, because for now it is of type varchar and 'CITY' should be a row name.

Answer 1

You will need to use the dynamic query in the cursor as follows. Also, you missed VALUES keyword in the INSERT statement which I have added (Please see inline comment in the codes)
Oracle sample data creation:
SQL> CREATE TABLE "EMPLOYEES" (
2 "ID" NUMBER,
3 "FIRSTNAME" VARCHAR2(100 BYTE),
4 "CITY" VARCHAR2(100 BYTE),
5 PRIMARY KEY ( "ID" ) USING INDEX ENABLE
6 );
Table created.
SQL>
Now, Let's create your procedure
SQL> CREATE OR REPLACE PROCEDURE INSERT_TABLE (
2 COLUMN_NAME IN VARCHAR2,
3 DAT IN VARCHAR2
4 ) AS
5
6 TABLE_NAME VARCHAR2(100) := COLUMN_NAME || '_' || DAT;
7 SQL_CREATE VARCHAR2(100) := 'create table ' || TABLE_NAME || '(FIRSTNAME varchar2(100))';
8 C_EMP SYS_REFCURSOR; -- declaration of cursor
9 LV_FNAME EMPLOYEES.FIRSTNAME%TYPE; -- to store the each value from cursor
10 BEGIN
11 EXECUTE IMMEDIATE SQL_CREATE;
12 OPEN C_EMP FOR 'SELECT FIRSTNAME
13 FROM EMPLOYEES
14 WHERE ' || COLUMN_NAME || ' = ''' || DAT || '''';
15 -- above statement used dynamic query in cursor
16 LOOP
17 FETCH C_EMP INTO LV_FNAME;
18 EXIT WHEN C_EMP%NOTFOUND;
19 EXECUTE IMMEDIATE 'INSERT INTO ' || TABLE_NAME || ' VALUES (''' || LV_FNAME || ''')'; -- added VALUES keyword in INSERT statement.
20 END LOOP;
21
22 COMMIT;
23 END INSERT_TABLE;
24 /
Let's execute it and see the result now.
SQL>
SQL> EXECUTE INSERT_TABLE('CITY', 'London');
PL/SQL procedure successfully completed.
SQL>
SQL>
SQL> SELECT * FROM CITY_LONDON;
FIRSTNAME
--------------------------------------------------------------------------------
TEJASH
SQL>
Ohh Yes, It created the desired table and also data is populated correctly.
Cheers!!

Answer 2

You are missing quotes. This
sql_str:='INSERT INTO '||table_name||'('||r_reg.firstname||');';
should be
sql_str:='INSERT INTO '||table_name||'('''||r_reg.firstname||''');';
This will turn INSERT INTO CITY_London (Peter); into INSERT INTO CITY_London ('Peter');.
And according to the docs (e.g. https://docs.oracle.com/cd/B19306_01/appdev.102/b14261/dynamic.htm):
When constructing a single SQL statement in a dynamic string, do not include a semicolon (;) at the end inside the quotation mark.
So the two SQL strings for EXECUTE IMMEDIATE should be:
sql_create varchar2(100) := 'create table ' || table_name || '(FIRSTNAME varchar2(100))';
and
sql_str := 'INSERT INTO ' || table_name || '(''' || r_reg.firstname || ''')';

Answer 3

It is the answer for your last question. You can pass parameters to the cursor like there:
declare
CURSOR c_emp(p_param varchar2) is
select p_param val
from dual;
begin
for r_reg in c_emp('b')
loop
dbms_output.put_line(r_reg.val);
end loop;
end;