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How can we use ORDER BY clause while calculating the Date?
It would be more convenient to find a record if we will use ORDER BY clause while calculating the date. To understand it, we have the data from table ‘Collegedetail’ as follows −
mysql> Select * from Collegedetail; +------+---------+------------+ | ID | Country | Estb | +------+---------+------------+ | 111 | INDIA | 2010-05-01 | | 130 | INDIA | 1995-10-25 | | 139 | USA | 1994-09-25 | | 1539 | UK | 2001-07-23 | | 1545 | Russia | 2010-07-30 | +------+---------+------------+ 5 rows in set (0.00 sec)
Now, suppose if we want to calculate the number of years a college is old then it can be done as follows −
mysql> Select ID, estb, CURDATE(),((YEAR(CURDATE())-YEAR(estb))-(RIGHT(CURDATE(),5)<RIGHT(estb,5))) AS 'YEARS_OLD' from collegedetail; +------+------------+------------+-----------+ | ID | estb | CURDATE() | YEARS_OLD | +------+------------+------------+-----------+ | 111 | 2010-05-01 | 2017-11-30 | 7 | | 130 | 1995-10-25 | 2017-11-30 | 22 | | 139 | 1994-09-25 | 2017-11-30 | 23 | | 1539 | 2001-07-23 | 2017-11-30 | 16 | | 1545 | 2010-07-30 | 2017-11-30 | 7 | +------+------------+------------+-----------+ 5 rows in set (0.00 sec)
Our search can be more convenient if we use ORDER BY clause as follows while calculating the number of years a college is old −
mysql> Select ID, estb, CURDATE(),((YEAR(CURDATE())-YEAR(estb))-(RIGHT(CURDATE(),5)<RIGHT(estb,5))) AS 'YEARS_OLD' from collegedetail ORDER BY YEARS_OLD; +------+------------+------------+-----------+ | ID | estb | CURDATE() | YEARS_OLD | +------+------------+------------+-----------+ | 111 | 2010-05-01 | 2017-11-30 | 7 | | 1545 | 2010-07-30 | 2017-11-30 | 7 | | 1539 | 2001-07-23 | 2017-11-30 | 16 | | 130 | 1995-10-25 | 2017-11-30 | 22 | | 139 | 1994-09-25 | 2017-11-30 | 23 | +------+------------+------------+-----------+ 5 rows in set (0.01 sec)
The above result set shows that we can search the oldest college very easily by using ORER BY clause with ‘YEARS_OLD’. We can also use DESC keyword with ORDER BY clause which returns the oldest college in the top row as follows −
mysql> Select ID, estb, CURDATE(),((YEAR(CURDATE())-YEAR(estb))-(RIGHT(CURDATE(),5)<RIGHT(estb,5))) AS 'YEARS_OLD' from collegedetail ORDER BY YEARS_O LD DESC; +------+------------+------------+-----------+ | ID | estb | CURDATE() | YEARS_OLD | +------+------------+------------+-----------+ | 139 | 1994-09-25 | 2017-11-30 | 23 | | 130 | 1995-10-25 | 2017-11-30 | 22 | | 1539 | 2001-07-23 | 2017-11-30 | 16 | | 111 | 2010-05-01 | 2017-11-30 | 7 | | 1545 | 2010-07-30 | 2017-11-30 | 7 | +------+------------+------------+-----------+ 5 rows in set (0.00 sec)
Updated on: 20-Jun-2020
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