INSERT INTO TAB SELECT * FROM TABLE TAB#db2 - Too many values - sql

Question

I'm trying to move rows between two tables which have many columns.
The table columns are identical other than the destination table (tab#db2) has a few more columns which causes a simple INSERT to fail.
I'd like to use a simple PL/SQL statement to build a list of the columns in tab#db2 dynamically instead of typing out the names of col1, col2, etc in the INSERT and SELECT clause. Example
declare a variable as var_col_list
set col_list = output of select * from tab (omitting rows)
INSERT INTO TAB *var_col_list* SELECT *var_cols_list* FROM TABLE TAB#db2
I've researched using %rowtype but cannot find a suitable example that would take less time than simply writing out the names of the columns!
Any advice is greatly appreciated

Answer 1

If you use e.g. TOAD, you can right-click the table and let it Generate statement - in your case, that would be INSERT. You'd slightly modify it (remove columns you don't need) and that's all.
Otherwise, this is how you might do it semi-manually.
This is my source table:
SQL> SELECT * FROM dept;
DEPTNO DNAME LOC
---------- -------------------- --------------------
10 ACCOUNTING NEW YORK
20 RESEARCH DALLAS
30 SALES CHICAGO
40 OPERATIONS BOSTON
Target table doesn't contain all columns:
SQL> CREATE TABLE target
2 (
3 deptno NUMBER,
4 dname VARCHAR2 (20)
5 );
Table created.
Code which loops through all TARGET table columns (i.e. a table which has less columns) and composes the INSERT INTO statement:
SQL> DECLARE
2 l_str VARCHAR2 (1000);
3 BEGIN
4 FOR cur_r IN (SELECT column_name
5 FROM user_tab_columns
6 WHERE table_name = 'TARGET')
7 LOOP
8 l_str := l_str || ', ' || cur_r.column_name;
9 END LOOP;
10
11 l_str :=
12 'insert into target select ' || LTRIM (l_str, ', ') || ' from dept';
13 DBMS_OUTPUT.put_line (l_str);
14
15 EXECUTE IMMEDIATE l_str;
16 END;
17 /
insert into target select DEPTNO, DNAME from dept --> this is the L_STR contents
PL/SQL procedure successfully completed.
SQL> SELECT * FROM target;
DEPTNO DNAME
---------- --------------------
10 ACCOUNTING
20 RESEARCH
30 SALES
40 OPERATIONS
Seems to be OK.

Answer 2

Using the solution provided by Littefoot, I made some minor tweaks to fit my requirement perfectly:
SQL> create table taba (col1 number,col2 number);
SQL> insert into taba values (1,2);
SQL> select * from taba;
COL1 COL2
---------- ----------
1 2
SQL> create table tabb (col1 number,col2 number, col3 number);
SQL> DECLARE
l_str VARCHAR2 (32767);
BEGIN
FOR cur_r IN (SELECT column_name
FROM user_tab_columns
WHERE table_name = 'TABA'
order by column_id asc)
LOOP
l_str := l_str || ', ' || cur_r.column_name;
END LOOP;
l_str :=
'insert into tabb (' || LTRIM (l_str, ', ') || ') ' ||' select ' || LTRIM (l_str, ', ') || ' from taba';
DBMS_OUTPUT.put_line (l_str);
EXECUTE IMMEDIATE l_str;
END;
/
Output of l_str (SQL INSERT):
insert into tabb (COL1, COL2) select COL1, COL2 from taba
Result:
SQL> select * from tabb;
COL1 COL2 COL3
---------- ---------- ----------
1 2