Where does mysql store data?
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Suppose you have to collect the first name, middle name and the last name of students from the below table. But, you observe that there few missing values either in the first name, middle name and the last name columns. How will you return the first non-null values?
Which command is used to view the content of the table in mysql?
mysql> select * from store; +------+-------+-------+ | id | month | sales | +------+-------+-------+ | 1 | 1 | 100 | | 1 | 2 | 100 | | 1 | 3 | 200 | | 1 | 4 | 300 | | 1 | 5 | NULL | | 1 | 6 | 200 | | 1 | 7 | 800 | | 1 | 8 | 100 | | 1 | 9 | 240 | | 1 | 10 | 140 | | 1 | 11 | 400 | | 1 | 12 | 300 | | 2 | 1 | 300 | | 2 | 2 | 300 | | 2 | 3 | 300 | | 2 | 4 | 200 | | 2 | 5 | 200 | | 2 | 6 | 200 | | 2 | 7 | 100 | | 2 | 8 | 100 | | 2 | 9 | 300 | | 2 | 10 | 100 | | 2 | 11 | 150 | | 2 | 12 | 150 | +------+-------+-------+ this is my table. i need to display output like this. +------+----------+----------+----------+----------+ | id | quarter1 | quarter2 | quarter3 | quarter4 | +------+----------+----------+----------+----------+ | 1 | 400 | 500 | 1140 | 840 | | 2 | 900 | 600 | 500 | 400 | +------+----------+----------+----------+----------+ what single query i have to write for this. i tried this query and it displays like the below mysql> select id,sum(sales) as quarter1,(select sum(sales) from store where mont h>3 and month<7 ) as quarter2,(select sum(sales) from store where month>6 and mo nth<10)as quarter3 from store where month>0 and month<4 group by id; +------+----------+----------+----------+ | id | quarter1 | quarter2 | quarter3 | +------+----------+----------+----------+ | 1 | 400 | 1100 | 1640 | | 2 | 900 | 1100 | 1640 | +------+----------+----------+----------+ 2 rows in set (0.00 sec) tel me how to rectify it.
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