Oracle 11g Release 2

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CREATE TABLE tab1
    ("Date" varchar2(5), "Dept" int, "Employee" varchar2(8))
;

INSERT ALL 
    INTO tab1 ("Date", "Dept", "Employee")
         VALUES ('08/18', 2, 'John')
    INTO tab1 ("Date", "Dept", "Employee")
    
         VALUES ('08/19', 1, 'Meredith')
    INTO tab1 ("Date", "Dept", "Employee")
         VALUES ('08/20', 9, 'Steve')
    INTO tab1 ("Date", "Dept", "Employee")
         VALUES ('08/21', 0, 'Bella')
SELECT * FROM dual
4 rows affected

SELECT "DAT"
FROM
(SELECT "Date","Dept",
 LAG("Date") OVER (ORDER BY
 "Date") dat FROM  tab1 ) t1
 WHERE "Dept" = 0


DAT


08/20


SELECT "Date", "Dept", "Employee" FROM tab1
WHERE "Date"  IN (SELECT "DAT"
FROM
(SELECT "Date","Dept",
 LAG("Date") OVER (ORDER BY
 "Date") dat FROM  tab1 ) t1
 WHERE "Dept" = 0
)


Date
Dept
Employee


08/20
9
Steve


SELECT 
"Date", "Dept", "Employee" FROM tab1 WHERE "Dept" = 0
UNION
SELECT "Date", "Dept", "Employee" FROM tab1
WHERE "Date"  IN (SELECT "DAT"
FROM
(SELECT "Date","Dept",
 LAG("Date") OVER (ORDER BY
 "Date") dat FROM  tab1 ) t1
 WHERE "Dept" = 0
)


Date
Dept
Employee


08/20
9
Steve

08/21
0
Bella