Differences Between Dates : Introduction « Date Timestamp Functions « Oracle PL/SQL Tutorial

1. Oracle PL/SQL Tutorial
2. Date Timestamp Functions
3. Introduction

SQL>
SQL> CREATE TABLE dept (
  2     deptID INT NOT NULL PRIMARY KEY,
  3     StudentID    INT NOT NULL,
  4     ClassID      INT NOT NULL,
  5     EnrolledOn   DATE,
  6     Grade        INT);

Table created.

SQL>
SQL> INSERT INTO dept (deptID,StudentID,ClassID,EnrolledOn,Grade) VALUES (1,1,1,DATE '2002-09-23',62);

1 row created.

SQL> INSERT INTO dept (deptID,StudentID,ClassID,EnrolledOn,Grade) VALUES (2,1,2,DATE '2002-09-30',70);

1 row created.

SQL> INSERT INTO dept (deptID,StudentID,ClassID,EnrolledOn,Grade) VALUES (3,2,3,DATE '2003-09-23',51);

1 row created.

SQL> INSERT INTO dept (deptID,StudentID,ClassID,EnrolledOn,Grade) VALUES (4,2,5,DATE '2003-09-23',41);

1 row created.

SQL> INSERT INTO dept (deptID,StudentID,ClassID,EnrolledOn,Grade) VALUES (5,2,6,DATE '2003-09-23',68);

1 row created.

SQL> INSERT INTO dept (deptID,StudentID,ClassID,EnrolledOn,Grade) VALUES (6,3,4,DATE '2002-09-30',78);

1 row created.

SQL> INSERT INTO dept (deptID,StudentID,ClassID,EnrolledOn,Grade) VALUES (7,3,7,DATE '2002-09-30',80);

1 row created.

SQL> INSERT INTO dept (deptID,StudentID,ClassID,EnrolledOn,Grade) VALUES (8,4,8,DATE '2002-09-20',70);

1 row created.

SQL> INSERT INTO dept (deptID,StudentID,ClassID,EnrolledOn,Grade) VALUES (9,4,5,DATE '2002-09-20',60);

1 row created.

SQL> INSERT INTO dept (deptID,StudentID,ClassID,EnrolledOn,Grade) VALUES (10,5,1,DATE '2002-09-23',33);

1 row created.

SQL>
SQL>
SQL> SELECT StudentID,
  2         FLOOR(MAX(CURRENT_DATE - EnrolledOn)) AS DaysEnrolled
  3  FROM dept
  4  GROUP BY StudentID
  5  ORDER BY DaysEnrolled DESC;

 STUDENTID DAYSENROLLED
---------- ------------
         4         2593
         1         2590
         5         2590
         3         2583
         2         2225

5 rows selected.

SQL>
SQL>
SQL> drop table dept;

Table dropped.