in a select statement, is the order of elements in the where clause the
determining factor on what records are chosen first, second etc?
for instance...
select fname from maintable where status=1 and dob > '2001-03-10';
does that mean that the records will first be checked for status creating a
pool of records with status=1 to then check for dob out of that pool or if
does it use some
Hi,
I have a query like this:
select id, title from product where id in (1,3,5,8,10)
What I want it to do is return the rows in the order specified in the
"in" clause, so that this:
select * from product where id in (10,3,8,5,1)
will give me results in this order:
+------+---------+
| id | title |
+------+---------+
| 10 | foo |
+------+---------+
| 3 | baz
Hello,
Would the order of partition column in the where clause matter for
performance?
For eg: would there be any difference in performance in the below queries?
select a from table where part_column = ‘y’ and non_part_column = ‘z’
or
select a from table where non_part_column = ‘z’ and part_column = ‘y’
Also, how can I make sure that “partition pruning” is working as intended
Hi,
I've got query like this:
"select count(ID) from TABLE where (TABLE.A + TABLE.B + TABLE.C + TABLE.D) >
0"
A,B,C,D are decimal values.
There are over 10000 records where A is greater than 0,
about 1000 where B is greater than 0,
about 500 where C is greater than 0,
and about 300 where D is greater 0.
I want to get a value of at least 10000 of course.
But I get a very small value
Hi All,
In MySql, you CAN'T do the following:
SELECT sales * cost AS total WHERE total > 100
Instead, you need to say:
SELECT sales * cost AS total WHERE sales * cost > 100
I'm just curious WHY you can't do it. You can, for example, specify ORDER
BY total.
I can't think of any reason why it would be either difficult or ambiguous
for the SQL engine to allow you to use your calculated
Hello,
I have a sql query as follows:
**************************
SELECT
DB_ESTABLISHMENT_NAME,
AVG(DB_GRADE)
FROM
ESTABLISHMENTS ES LEFT OUTER JOIN GRADES GR ON
ES.DB_ESTABLISHMENT_ID=GR.DB_ESTABLISHMENT_ID
WHERE
AVG(DB_GRADE) > 2
GROUP BY
ES.DB_ESTABLISHMENT_ID
;
**************************
and I get the following error:
ERROR 1111: Invalid use of group function
Hi.
I have two tables. One that contains movies and one that contains grades
that readers have given to the movies. I want to select the most popular
movies and list them. This is not a problem really. The hard part is to
limit the results to movies that have gotten atleast 5 grades (something
like how IMDb does).
I've been going through chapter 7.4 (Functions for use in select and where
Hello Tom,
TB> I have a database with a first and last name fields that I would like to
TB> combine for a search. Basically on my web page interface I would like the
TB> end user to fill out one field instead of individual first and last fields.
TB> I tried writing a query like so;
TB> SELECT id, CONCAT(first," ",last) AS name FROM ceem_founder WHERE
TB> status='live' AND name LIKE '%Sam
Hello -
Can functions such as IF, ISNULL, IFNULL & DATE_FORMAT be used in the WHERE
clause of a query? I am getting syntax errors when trying this, the same
code works fine in the select part.
E.g.
select even.id
,even.event_name
,even.evca_id
,ifnull(evca.id,"null value")
,evca.description_en
from events even
left join event_categories evca
on even
I have a database with a first and last name fields that I would like to
combine for a search. Basically on my web page interface I would like the
end user to fill out one field instead of individual first and last fields.
I tried writing a query like so;
SELECT id, CONCAT(first," ",last) AS name FROM ceem_founder WHERE
status='live' AND name LIKE '%Sam Spade%'
I get an error that the "name
