Dates between date1 and date2 are not working in cross joining - sql

Question

Hi I am trying to filter data with dates between but it insert null 0 rows created its cross joining table I am not aware is there problem due to cross joining or something else. There is no error message
without dates it works fine any solution Please
insert into PAY_IN_OUT2 (EMP_CODE, DATE_IN, DATE_OUT, ATT_DATE, DATE_INA, DATE_OUTA, DATE_INB, DATE_OUTB, DATE_INC, DATE_OUTC, ATT_PRESENT)
select a.EMPLOYEE_ID1, b.DT, b.DT1, B.ATT_DT, B.DT3, B.DT4, B.DT4, B.DT5, B.DT5, B.DT3, 'P'
from CALENDAR_DATES4 b cross join EMPLOYEES a
WHERE A.EMPLOYEE_ID1 BETWEEN 70001 AND 70009
AND B.ATT_DT BETWEEN TO_DATE('10/02/2021', 'DD/MM/YYYY') AND TO_DATE('20/02/2021', 'DD/MM/YYYY') ;
without this its working fine but I have to filter this with dates AND B.ATT_DT BETWEEN TO_DATE('10/02/2021', 'DD/MM/YYYY') AND TO_DATE('20/02/2021', 'DD/MM/YYYY')

Answer 1

If you're cross joining two tables and filtering on each table, and you end up selecting 0 rows, then at least one of your predicates is causing no rows to be returned.
For example, here's a set of queries demonstrating some different results, depending on what the predicates cause to be returned:
WITH t1 AS (SELECT 1 ID, 10 val FROM dual UNION ALL
SELECT 2 ID, 20 val FROM dual UNION ALL
SELECT 3 ID, 30 val FROM dual UNION ALL
SELECT 4 ID, 40 val FROM dual UNION ALL
SELECT 5 ID, 50 val FROM dual),
t2 AS (SELECT 'A' col1, 'AA' col2 FROM dual UNION ALL
SELECT 'B' col1, 'BA' col2 FROM dual UNION ALL
SELECT 'C' col1, 'AC' col2 FROM dual UNION ALL
SELECT 'D' col1, 'DD' col2 FROM dual)
SELECT 1 case_no, -- case 1: no rows expected to be returned (no t1 rows with an id between 6 and 10)
t1.*,
t2.*
FROM t1
CROSS JOIN t2
WHERE t1.id BETWEEN 6 AND 10
AND t2.col2 LIKE 'A%'
UNION ALL
SELECT 2 case_no, -- case 2: no rows expected to be returned (no t2 rows with a col2 starting with "C")
t1.*,
t2.*
FROM t1
CROSS JOIN t2
WHERE t1.id BETWEEN 2 AND 4
AND t2.col2 LIKE 'C%'
UNION ALL
SELECT 3 case_no, -- case 3: no rows expected to be returned (no t1 rows with an id between 6 and 10, and no t2 rows with a col2 starting with "C")
t1.*,
t2.*
FROM t1
CROSS JOIN t2
WHERE t1.id BETWEEN 6 AND 10
AND t2.col2 LIKE 'C%'
UNION ALL
SELECT 4 case_no, -- case 4: 6 rows expected to be returned (3 t1 rows with an id between 2 and 4, and 2 t2 rows with a col2 starting with "A"; 3 x 2 = 6)
t1.*,
t2.*
FROM t1
CROSS JOIN t2
WHERE t1.id BETWEEN 2 AND 4
AND t2.col2 LIKE 'A%';
CASE_NO ID VAL COL1 COL2
---------- ---------- ---------- ---- ----
4 2 20 A AA
4 3 30 A AA
4 4 40 A AA
4 2 20 C AC
4 3 30 C AC
4 4 40 C AC
You can see that only case 4 (rows in both tables match the predicates) has any rows returned by the cross join.
ETA: if you were wanting to see employee rows regardless of whether there are matching date rows or not, you would need to use an outer join, e.g. using my earlier example, case 2 would become:
WITH t1 AS (SELECT 1 ID, 10 val FROM dual UNION ALL
SELECT 2 ID, 20 val FROM dual UNION ALL
SELECT 3 ID, 30 val FROM dual UNION ALL
SELECT 4 ID, 40 val FROM dual UNION ALL
SELECT 5 ID, 50 val FROM dual),
t2 AS (SELECT 'A' col1, 'AA' col2 FROM dual UNION ALL
SELECT 'B' col1, 'BA' col2 FROM dual UNION ALL
SELECT 'C' col1, 'AC' col2 FROM dual UNION ALL
SELECT 'D' col1, 'DD' col2 FROM dual)
SELECT t1.*,
t2.*
FROM t1
LEFT OUTER JOIN t2 ON t2.col2 LIKE 'C%'
WHERE t1.id BETWEEN 2 AND 4;
ID VAL COL1 COL2
---------- ---------- ---- ----
2 20
3 30
4 40