MySQL Query output using if else or case..? - mysql

Question

I have a table as
mysql> select * FROM testa;
+---------+-------+
| month_x | money |
+---------+-------+
| 11101 | 12345 |
| 11105 | 100 |
| 11105 | 100 |
| 11105 | 100 |
| 11105 | 100 |
| 11106 | 12345 |
+---------+-------+
6 rows in set (0.00 sec)
where last two digits in the month_x are months now i want my output as
Month TOTAL
01 12345
02 0
03 0
04 0
05 400
06 12345
07 0
08 0
09 0
10 0
11 0
12 0
IS possible using the If else or case.

Answer 1

You can use modular arithmetic to obtain the trailing two digits (they're the remainder when the number is divided by 100), then assuming you wish to sum money when your data is "grouped by" month:
SELECT month_x % 100 AS Month, SUM(money) AS TOTAL
FROM testa
GROUP BY Month
ORDER BY Month ASC;
Alternatively, you could use rely on MySQL's implicit type conversion and use its string functions:
SELECT RIGHT(month_x, 2) AS Month, SUM(money) AS TOTAL
FROM testa
GROUP BY Month
ORDER BY Month ASC;
UPDATE
As #shiplu.mokadd.im states, to show every month (even those for which you have no data), you need to obtain numbers 1 through 12 from a temporary table. However, you can create such a temporary table in your query using UNION:
SELECT 1
UNION SELECT 2
UNION SELECT 3 -- etc
Therefore:
SELECT Month, Sum(money) AS TOTAL
FROM testa
RIGHT JOIN (
SELECT 1 AS Month
UNION SELECT 2 UNION SELECT 3 UNION SELECT 4 UNION SELECT 5 UNION SELECT 6
UNION SELECT 7 UNION SELECT 8 UNION SELECT 9 UNION SELECT 10 UNION SELECT 11
UNION SELECT 12
) months ON testa.month_x % 100 = months.Month
GROUP BY Month;
HOWEVER I would note that usually one doesn't usually do this in the database, as it really belongs in the presentation layer: from whatever language you're accessing the database, you'd loop over 1...12 and assume TOTAL to be 0 if there's no corresponding record in the resultset.

Answer 2

For this you need to create a table first with months' numeric value in it.
CREATE TABLE `months` (
`mon` int(11) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8
INSERT INTO `months` VALUES (1), (2), (3), (4), (5), (6), (7), (8), (9), (10), (11), (12);
Then execute this query,
SELECT m.mon,
IF(Sum(t.money) IS NULL, 0, Sum(t.money)) AS `money`
FROM testa t
RIGHT OUTER JOIN months m
ON ( t.month_x%100 = m.mon )
GROUP BY m.mon;
Result is,
+------+-------+
| mon | money |
+------+-------+
| 1 | 12345 |
| 2 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 400 |
| 6 | 12345 |
| 7 | 0 |
| 8 | 0 |
| 9 | 0 |
| 10 | 0 |
| 11 | 0 |
| 12 | 0 |
+------+-------+

Answer 3

You can use IF statements - yes.
Look # this:
http://dev.mysql.com/doc/refman/5.5/en/if-statement.html