MySQL Forums
Forum List  »  Newbie

Re: EXPLAIN on SELECT is confusing me
Posted by: john flood
Date: March 17, 2009 10:04AM

OK,
I've read the section & I have made changes that I think are necesssary & changed my query to a simpler one to test but still get more or less the same results.

QUERY
EXPLAIN SELECT EDPG_SchAttYearCode AS School_Year, 
EDPG_SchAttTermCode AS School_Term, 
COUNT( DISTINCT (EDPG_UPN) ) AS Total_Pupils
FROM EDPG_PupilGrouped
GROUP BY 
School_Year, School_Term

INDEX CREATED
Keyname:EDPG_YrTermCode	
Type:BTREE
Unique:NO
Packed:NO
Field:EDPG_SchAttYearCode | EDPG_SchAttTermCode
Cardinality: 1 | 5
Collation: A | A

RESULTS
id 	select_type 	table 	type 	possible_keys 	key 	key_len 	ref 	rows 	Extra
1 	SIMPLE 	EDPG_PupilGrouped 	ALL 	NULL 	NULL 	NULL 	NULL 	243425 	Using filesort

Options: ReplyQuote


Subject
Written By
Posted
Re: EXPLAIN on SELECT is confusing me
March 17, 2009 10:04AM


Sorry, you can't reply to this topic. It has been closed.

Content reproduced on this site is the property of the respective copyright holders. It is not reviewed in advance by Oracle and does not necessarily represent the opinion of Oracle or any other party.