Using SQL date Variable with TOAD

I want to use a variable in TOAD for an WITH-SQL-Statement because today's date is used multiple times.

I tried with variable, DEFINE and Declare for setting the variable up but it didn't work yet.

Skript should look something like this:

DECLARE TODAY date := SYSDATE();

BEGIN
WITH

SUBQUERY1 AS (
SELECT *
FROM TABLE
WHERE TABLE.DATE = &TODAY
),

SUBQUERY2 AS (
SELECT *
FROM TABLE2
WHERE TABLE2.DATE = &TODAY
),

SELECT *
FROM TABLE3 
JOIN SUBQUERY1 ON TABLE3.PRIMARYKEY = SUBQUERY1.PRIMARYKEY
JOIN SUBQUERY2 ON TABLE3.PRIMARYKEY = SUBQUERY2.PRIMARYKEY

END;

While researching I've read something about an into statement but I think it's used when you want to define the output of the query to the variable? Maybe someone can also provide me with an helpful article or so on.

Don't use PL/SQL, just use a query (and make sure you have closing brackets for the sub-query factoring clauses and a comma between them):

WITH dates (dt) AS (
  SELECT SYSDATE
  FROM   DUAL
),
SUBQUERY1 AS (
  SELECT t.*
  FROM   TABLE t
         INNER JOIN dates d
         ON (t.DATE = d.dt)
),
SUBQUERY2 AS (
  SELECT t2.*
  FROM   TABLE2 t2
         INNER JOIN dates d
         ON (t2.DATE = d.dt)
)
SELECT *
FROM   TABLE3 
       JOIN SUBQUERY1 ON TABLE3.PRIMARYKEY = SUBQUERY1.PRIMARYKEY
       JOIN SUBQUERY2 ON TABLE3.PRIMARYKEY = SUBQUERY2.PRIMARYKEY

Note: You do not need a variable for the date.

In Oracle, a DATE always has date and time components (even if the client application does not always show it). If you want results for the entire day (rather than for the current instant) then use:

WITH dates (dt) AS (
  SELECT TRUNC(SYSDATE)
  FROM   DUAL
),
SUBQUERY1 AS (
  SELECT t.*
  FROM   TABLE t
         INNER JOIN dates d
         ON (   t.DATE >= dt
            AND t.DATE <  dt + INTERVAL '1' DAY)
),
SUBQUERY2 AS (
  SELECT t2.*
  FROM   TABLE2 t2
         INNER JOIN dates d
         ON (   t2.DATE >= dt
            AND t2.DATE <  dt + INTERVAL '1' DAY)
)
SELECT *
FROM   TABLE3 
       JOIN SUBQUERY1 ON TABLE3.PRIMARYKEY = SUBQUERY1.PRIMARYKEY
       JOIN SUBQUERY2 ON TABLE3.PRIMARYKEY = SUBQUERY2.PRIMARYKEY