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SQL>
SQL> CREATE TABLE emp (
2 emp_id NUMBER,
3 ename VARCHAR2(40),
4 hire_date DATE DEFAULT sysdate,
5 end_date DATE,
6 rate NUMBER(5,2),
7 CONSTRAINT emp_pk PRIMARY KEY (emp_id)
8 );
Table created.
SQL> INSERT INTO emp(emp_id, ename, hire_date,end_date, rate)VALUES (101, 'Mary', to_date('15-Nov-1961','dd-mon-yyyy'),null,169);
1 row created.
SQL> INSERT INTO emp(emp_id, ename, hire_date,end_date, rate)VALUES (102, 'Tom', to_date('16-Sep-1964','dd-mon-yyyy'),to_date('5-May-2004','dd-mon-yyyy'),135);
1 row created.
SQL> INSERT INTO emp(emp_id, ename, hire_date,end_date, rate)VALUES (104, 'Peter', to_date('29-Dec-1987','dd-mon-yyyy'),to_date('1-Apr-2004','dd-mon-yyyy'),99);
1 row created.
SQL> INSERT INTO emp(emp_id, ename, hire_date,end_date, rate)VALUES (105, 'Mike', to_date('15-Jun-2004','dd-mon-yyyy'),null,121);
1 row created.
SQL> INSERT INTO emp(emp_id, ename, hire_date,end_date, rate)VALUES (107, 'Less', to_date('2-Jan-2004','dd-mon-yyyy'),null,45);
1 row created.
SQL> INSERT INTO emp(emp_id, ename, hire_date,end_date, rate)VALUES (108, 'Park', to_date('1-Mar-1994','dd-mon-yyyy'),to_date('15-Nov-2004','dd-mon-yyyy'),220);
1 row created.
SQL> INSERT INTO emp(emp_id, ename, hire_date,end_date, rate)VALUES (110, 'Ink', to_date('4-Apr-2004','dd-mon-yyyy'),to_date('30-Sep-2004','dd-mon-yyyy'),84);
1 row created.
SQL> INSERT INTO emp(emp_id, ename, hire_date,end_date, rate)VALUES (111, 'Tike', to_date('23-Aug-1976','dd-mon-yyyy'),null,100);
1 row created.
SQL> INSERT INTO emp(emp_id, ename, hire_date,end_date, rate)VALUES (112, 'Inn', to_date('15-Nov-1961','dd-mon-yyyy'),to_date('4-Apr-2004','dd-mon-yyyy'),70);
1 row created.
SQL> INSERT INTO emp(emp_id, ename, hire_date,end_date, rate)VALUES (113, 'Kate', to_date('3-Mar-2004','dd-mon-yyyy'),to_date('31-Oct-2004','dd-mon-yyyy'),300);
1 row created.
SQL>
SQL>
SQL> SET ECHO ON
SQL> SELECT all_dates.emp_date, COUNT(*)
2 FROM (
3 SELECT hire_date emp_date
4 FROM emp
5 UNION ALL
6 SELECT end_date
7 FROM emp) all_dates
8 GROUP BY all_dates.emp_date
9 ORDER BY COUNT(*) DESC;
4
15-NOV-61 2
04-APR-04 2
02-JAN-04 1
03-MAR-04 1
01-APR-04 1
05-MAY-04 1
15-JUN-04 1
30-SEP-04 1
31-OCT-04 1
15-NOV-04 1
01-MAR-94 1
29-DEC-87 1
23-AUG-76 1
16-SEP-64 1
15 rows selected.
SQL>
SQL>
SQL> drop table emp;
Table dropped.
SQL>
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