How do i copy old columns to my new existing table? - sql

Question

I have an existing new table that has no columns yet. I want to copy all 10 columns in my old table. How do i do that? I don't want to drop the table so I could perform: create table newTable as select * from oldTable.

Answer 1

I don't want to drop the table so I could perform:
create table newTable as select * from oldTable.
Assuming your new table has at least 1 column BobC told you cannot have a table without any column, you can alter your table.
Alter new_table add (col1 varchar2(10)) , col2 ...);
Note that you need to mention all the column same as old table manually here.
If you don't want to do this manually then probably you would need a PLSQL block to do this.
CREATE OR REPLACE PROCEDURE creat_tbl_frm_tbl (tablname VARCHAR2)
AS
db_user VARCHAR2 (100) := USER;
TYPE t_rec IS RECORD
(
COLUMN_NAME VARCHAR2 (30 BYTE),
DATA_TYPE VARCHAR2 (106 BYTE),
DATA_LENGTH NUMBER
);
TYPE t_record IS TABLE OF t_rec;
-- initialization of record
v_record t_record := t_record ();
v_cntr NUMBER := 0;
v_status NUMBER;
sql_stmt VARCHAR2 (2000);
BEGIN
---dropping Already Existing temporary table
BEGIN
SELECT 1
INTO v_status
FROM all_objects
WHERE UPPER (object_name) = UPPER (tablname) AND owner = db_user;
--dbms_output.put_line( v_status );
IF v_status = 1
THEN
sql_stmt := 'drop table ' || tablname || '_new';
EXECUTE IMMEDIATE sql_stmt;
END IF;
EXCEPTION
WHEN NO_DATA_FOUND
THEN
DBMS_OUTPUT.put_line ('Table not found--' || tablname);
WHEN OTHERS
THEN
DBMS_OUTPUT.put_line (
'Error while dropping table-' || SQLCODE || SQLERRM);
END;
---------------------------------------------------------------------------
---- retrieving the columns of the table
BEGIN
SELECT column_name, data_type, data_length
BULK COLLECT INTO v_record
FROM all_tab_columns
WHERE table_name = UPPER (tablname)
ORDER BY column_id;
EXCEPTION
WHEN OTHERS
THEN
DBMS_OUTPUT.put_line (
'Error while retrieving the column details-' || SQLCODE || SQLERRM);
END;
FOR i IN 1 .. v_record.COUNT
LOOP
v_cntr := v_cntr + 1;
IF v_cntr = 1
THEN
IF v_record (i).data_type = 'DATE'
OR UPPER (v_record (i).data_type) = 'TIMESTAMP(6)'
THEN
sql_stmt :=
'create table '
|| ' '
|| tablname
|| '_new'
|| '('
|| v_record (i).column_name
|| ' '
|| v_record (i).data_type
|| ')';
ELSE
sql_stmt :=
'create table '
|| ' '
|| tablname
|| '_new'
|| '('
|| v_record (i).column_name
|| ' '
|| v_record (i).data_type
|| '('
|| v_record (i).data_length
|| '))';
END IF;
--dbms_output.put_line(sql_stmt);
EXECUTE IMMEDIATE sql_stmt;
ELSE
IF v_record (i).data_type = 'DATE'
OR UPPER (v_record (i).data_type) = 'TIMESTAMP(6)'
THEN
sql_stmt :=
'alter table'
|| ' '
|| tablname
|| '_new'
|| ' '
|| 'add ('
|| v_record (i).column_name
|| ' '
|| v_record (i).data_type
|| ')';
ELSE
sql_stmt :=
'alter table'
|| ' '
|| tablname
|| '_new'
|| ' '
|| 'add ('
|| v_record (i).column_name
|| ' '
|| v_record (i).data_type
|| '('
|| v_record (i).data_length
|| '))';
END IF;
--dbms_output.put_line(sql_stmt);
EXECUTE IMMEDIATE sql_stmt;
END IF;
END LOOP;
DBMS_OUTPUT.put_line ('Process Completed Successfully..!!');
END;
Output:
SQL> exec creat_tbl_frm_tbl('table2')
Process Completed Successfully..!!
PL/SQL procedure successfully completed.
SQL> select * from table2;
no rows selected
-- This is created with same columns as of passed table table2
SQL> select * from table2_new;
no rows selected

Answer 2

SELECT col1,col2,col3 --...
INTO newTable
FROM oldTable