Creating table with defined variable - sql

Question

I work in SQL Developer by Oracle. I have a simple query to creating new table based on condition where. I want to generate new table with defined variable like below. My code isn't working. How can I define variable and put its directly to query without any entry box?
DEFINE STARTDATE DATE:="TO_DATE('2021-06-01','YYYY-MM-DD')"
CREATE TABLE RESULTS AS
SELECT
*
FROM TABLE_1
WHERE DATA=ADD_MONTHS(:STARTDATE,2);

Answer 1

DEFINE creates a substitution variable.
:STARTDATE uses a bind variable, it is not a substitution variable.
&startdate would be a substution variable.
You want something like:
DEFINE STARTDATE = "DATE '2021-06-01'"
CREATE TABLE RESULTS AS
SELECT *
FROM TABLE_1
WHERE DATA=ADD_MONTHS(&STARTDATE,2);

Answer 2

That's not how define variables works. It is just a text replacement, not a pl/sql variable. try this:
DEFINE STARTDATE =TO_DATE('2021-06-01','YYYY-MM-DD')

Answer 3

In SQL*Plus, it is a substitution variable you'd use (BTW, define syntax you used is wrong).
For example:
SQL> select * From emp order by hiredate;
EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
---------- ---------- --------- ---------- -------- ---------- ---------- ----------
7369 SMITH CLERK 7902 17.12.80 800 20
7499 ALLEN SALESMAN 7698 20.02.81 1600 300 30
7521 WARD SALESMAN 7698 22.02.81 1250 500 30
7566 JONES MANAGER 7839 02.04.81 2975 20
7698 BLAKE MANAGER 7839 01.05.81 2850 30
7782 CLARK MANAGER 7839 09.06.81 2450 10
7844 TURNER SALESMAN 7698 08.09.81 1500 0 30
7654 MARTIN SALESMAN 7698 28.09.81 1250 1400 30
7839 KING PRESIDENT 17.11.81 5000 10
7900 JAMES CLERK 7698 03.12.81 950 30
7902 FORD ANALYST 7566 03.12.81 3000 20
7934 MILLER CLERK 7782 23.01.82 1300 10
7788 SCOTT ANALYST 7566 09.12.82 3000 20
7876 ADAMS CLERK 7788 12.01.83 1100 20
14 rows selected.
Create a table out of it:
SQL> DEFINE STARTDATE = "1980-12-01"
SQL> create table a1 as select * from emp where trunc(hiredate, 'mm') =
2 trunc(add_months(to_date('&startdate', 'yyyy-mm-dd'), 2));
old 2: trunc(add_months(to_date('&startdate', 'yyyy-mm-dd'), 2))
new 2: trunc(add_months(to_date('1980-12-01', 'yyyy-mm-dd'), 2))
Table created.
SQL> select * from a1;
EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
---------- ---------- --------- ---------- -------- ---------- ---------- ----------
7499 ALLEN SALESMAN 7698 20.02.81 1600 300 30
7521 WARD SALESMAN 7698 22.02.81 1250 500 30
SQL>