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Tag: Mysql

Drop Index

One common mistake which is being made on dropping index is that we forget the index name and try to drop the column name.

drop index departments_name_unique on departments;

CONCAT()

Incase if you want to join the fields

SELECT  DATE, expiry, CONCAT( user.b_fname, " ", user.b_lname ) 
FROM user

Joins

Different types of joins: inner joins, left joins, right joins union/outer joins. This link explains in great detail.

Happy coding!!

….Sometime simple tip makes someone’s coding life easier…………

Using group in MySQL:

Group by is being used to group field into a single row to perform count, sum avg etc.

SELECT *
FROM `test_results` 
WHERE parent_code =11
GROUP BY username

Using Group by with MAX

SELECT MAX( points ) , username
FROM `test_results` 
WHERE parent_code =11
GROUP BY username

Similar can be used for min, avg, count…etc

Using Group by with Having

select gid
 from `gd`
 group by gid
 having count(*) > 10
order by lastupdated desc

Happy coding!!

….Sometime simple tip makes someone’s coding life easier…………