I have two tables, one is for individuals and the other is for their company.
Each table has a column for locale, this is mandatory for the company, but not for the individual. The idea seems to be that if the individual doesn't set a preference, they are assumed to be in the locale of their company.
I would like to select the locale for the individual, using the company default if the individual locale is null and I thought of doing the following (which I don't think is possible in MySql)...
SELECT
ISNULL(individual.Locale, company.Locale) `Locale`
FROM
individual
INNER JOIN
company ON company.CompanyId = individual.CompanyId
WHERE
individual.IndividualId = 1
Is there a nice way to do this - or am I just going to end up sending both Locale's back and making the decision in the code?
You can use the COALESCE() function which returns the first non-NULL value among its arguments. This function can also be used in most other RDBMS like SQL-Server, Oracle 9, Postgres 8:
SELECT
COALESCE(individual.Locale, company.Locale) AS Locale
FROM
individual
INNER JOIN
company ON company.CompanyId = individual.CompanyId
WHERE
individual.IndividualId = 1
You pretty much had it, what you want is IFNULL()
SELECT
IFNULL(individual.Locale, company.Locale) `Locale`
FROM
individual
INNER JOIN
company ON company.CompanyId = individual.CompanyId
WHERE
individual.IndividualId = 1
Try the CASE...WHEN...THEN statement
SELECT
(CASE
WHEN individual.Locale IS NULL THEN company.Locale
ELSE individual.Locale
END) 'Locale'
FROM
individual
INNER JOIN
company ON company.CompanyId = individual.CompanyId
WHERE
individual.IndividualId = 1
Related
Hopefully i can explain this well enough. I have a bit of a unique issue where the customer system we use can change a ID in the database in the background based on the products status.
What this means is when i want to report old products we don't use anymore along side active products there ID differs between the two key tables depending on there status. This means Active products in the product table match that of the stock item table with both showing as 647107376 but when the product is no long active the StockItem table will present as 647107376 but the table that holds the product information the id presents as -647107376
This is proving problematic for me when i comes to joining the tables together to get the information needed. Originally i had my query set up like this:
SELECT
Company_0.CoaCompanyName
,SopProduct_0.SopStiStockItemCode AS hbpref
,SopProduct_0.SopStiCustomerStockCode AS itemref
,SopProduct_0.SopDescription AS ldesc
,StockMovement_0.StmOriginatingEntityID AS Goodsin
FROM
SBS.PUB.StockItem StockItem_0
LEFT JOIN SBS.PUB.SopProduct SopProduct_0 ON StockItem_0.StockItemID = SopProduct_0.StockItemID
LEFT JOIN SBS.PUB.Company Company_0 ON SopProduct_0.CompanyID = Company_0.CompanyID
LEFT JOIN SBS.PUB.StockMovement StockMovement_0 ON StockItem_0.StockItemID = StockMovement_0.StockItemID
WHERE
Company_0.CoaCompanyName = ?
AND StockMovement_0.MovementTypeID = '173355'
AND StockMovement_0.StmMovementDate >= ? AND StockMovement_0.StmMovementDate <= ?
AND StockMovement_0.StmQty <> 0
AND StockMovement_0.StockTypeID ='12049886'
Unfortunately though what this means is any of the old product will not show because there is no matching id due to the SopProduct table presenting the StockItemID with a leading -
So from this i thought best to use a case when statement with a nested concat and left in it to bring through the results but this doesn't appear to work either sample of the join below:
LEFT JOIN SBS.PUB.SopProduct SopProduct_0 ON (CASE WHEN LEFT(SopProduct_0.StockItemID,1) = "-" THEN CONCAT("-",StockItem_0.StockItemID) ELSE StockItem_0.StockItemID END) = SopProduct_0.StockItemID
Can anyone else think of a way around this issue? I am working with a Progress OpenEdge ODBC.
Numbers look like numbers. If they are, you can use abs():
ON StockItem_0.StockItemID = ABS(SopProduct_0.StockItemID)
Otherwise a relatively simple method is:
ON StockItem_0.StockItemID IN (SopProduct_0.StockItemID, CONCAT('-', SopProduct_0.StockItemID))
Note that non-equality conditions often slow down JOIN operations.
Using an or in the join should work:
LEFT JOIN SBS.PUB.SopProduct SopProduct_0
ON SopProduct_0.StockItemID = StockItem_0.StockItemID
OR
SopProduct_0.StockItemID = CONCAT("-", StockItem_0.StockItemID)
You might need to cast the result of the concat to a number (if the ids are stored as numbers).
Or you could use the abs function too (assuming the ids are numbers):
LEFT JOIN SBS.PUB.SopProduct SopProduct_0
ON SopProduct_0.StockItemID = abs(StockItem_0.StockItemID)
Good day,
I have a small issue with MySQL Distinct.
Trying the following query in my system :
SELECT DISTINCT `booking_id`, `booking_ticket`, `booking_price`, `bookingcomment_id`, `bookingcomment_message` FROM `mysystem_booking`
LEFT JOIN `mysystem_bookingcomment` ON `mysystem_booking`.`booking_id` = `mysystem_bookingcomment`.`bookingcomment_link`
WHERE `booking_id` = 29791
The point is that there are bookings like 29791 that have many comments added.
Let's say 10. Then when running the above query I see 10 results instead of one.
And that's not the way DISTINCT supposes to work.
I simply want to know if there are any comments. If the comment ID is not 0 then there is a comment. Of course I can add COUNT(blabla) as comment_number but that's a whole different story. For me now I'd like just to have this syntax right.
You may try aggregating here, to find which bookings have at least a single comment associated with them:
SELECT
b.booking_id,
b.booking_ticket,
b.booking_price
FROM mysystem_booking b
LEFT JOIN mysystem_bookingcomment bc
ON b.booking_id = bc.bookingcomment_link
WHERE
b.booking_id = 29791
GROUP BY
b.booking_id
HAVING
COUNT(bc.bookingcomment_link) > 0;
Note that depending on your MySQL server mode, you might have to also add the booking_ticket and booking_price columns to the GROUP BY clause to get the above query to run.
You can try below - using a case when expression
SELECT DISTINCT `booking_id`, `booking_ticket`, `booking_price`, `bookingcomment_id`,
case when `bookingcomment_message`<>'0' then 'No' else 'Yes' end as comments
FROM `mysystem_booking`
LEFT JOIN `mysystem_bookingcomment` ON `mysystem_booking`.`booking_id` = `mysystem_bookingcomment`.`bookingcomment_link`
WHERE `booking_id` = 29791
Before anyone says, I have searched through for a suitable answer for my issue but cannot find anything specific enough so I thought I'd ask it.
Basically I am trying to select a bunch of data for a report of people who have made loan applications to a website, but there are two different types: unsecured and guarantee. I need to place an IFNULL statement in the WHERE clause so that I ONLY use that clause if a certain other field isn't null.
Here is my statement:
SELECT
la.`lms_loan_application_id`,
la.`created`,
la.`updated`,
la.`loan_amount`,
la.`loan_term`,
la.`loan_document_fee`,
la.`broker_reference`,
la.`broker_sub_reference`,
laa.`first_name`,
laa.`surname`,
laa.`dob`,
laa.`email`,
laa.`mobile_number`,
laaAd.`address_postcode`,
lag.`first_name`,
lag.`surname`,
lag.`dob`,
lag.`email`,
lag.`mobile_number`,
lagAd.`address_postcode`,
lagAd.`housing_status`
FROM
loan_application AS la
JOIN
loan_application_applicant AS laa ON la.`id` = laa.`loan_application`
LEFT JOIN
loan_application_guarantor AS lag ON la.`id` = lag.`loan_application`
JOIN
loan_application_address AS laaAd ON laaAd.`loan_application_applicant` = laa.`id`
LEFT JOIN
loan_application_address AS lagAd ON lagAd.`loan_application_guarantor` = lag.`id`
WHERE
la.`status` = 'signature_given'
AND ! IFNULL(lag.`first_name`,
lag.`status` = 'signature_given')
AND laa.`status` = 'signature_given'
AND ! IFNULL(lag.`first_name`,
lagAd.`current_address` = 1)
AND laaAd.`current_address` = 1
ORDER BY la.`updated` DESC
LIMIT 10000
As you can see, I have attempted to use the IFNULLs (although in a negated way, which I assume works?) but all I get is duplicate row results and not the result set I really want.
Basically, I need to use the where clause "lag.status = 'signature_given" and "lagAd.current_address = 1" ONLY if the lag.first_name field is NOT null (i.e. there is a guarantor name) otherwise the status won't exist, and therefore the results of unsecured loans will not show. Hope I'm explaining this well enough!
In summary, I need to show all loan information, unsecured and guaranteed, and use a negated IFNULL in order to determine when the WHERE clause is to be taken into consideration.
Any help appreciated!
Thank you in advance
Michael
From this MySQLTutorial article:
Notice that you should avoid using the IFNULL function in the WHERE clause, because it degrades the performance of the query. If you want to check if a value is NULL or not, you can use IS NULL or IS NOT NULL in the WHERE clause.
Here is a WHERE clause which implements your logic correctly using IS NULL and IS NOT NULL instead of IFNULL:
WHERE la.`status` = 'signature_given' AND
(lag.`first_name` IS NULL OR
(lag.`first_name` IS NOT NULL AND lag.`status` = 'signature_given')) AND
laa.`status` = 'signature_given' AND
(lag.`first_name` IS NULL OR
(lag.`first_name` IS NOT NULL AND lagAd.`current_address` = 1)) AND
laaAd.`current_address` = 1
dont blame for the database design.I am not its database architect. I am the one who has to use it in current situation
I hope this will be understandable.
I have 3 tables containing following data with no foreign key relationship b/w them:
groups
groupId groupName
1 Admin
2 Editor
3 Subscriber
preveleges
groupId roles
1 1,2
2 2,3
3 1
roles
roleId roleTitle
1 add
2 edit
Query:
SELECT roles
from groups
LEFT JOIN preveleges ON (groups.groupId=preveleges.groupId)
returns specific result i.e roles.
Problem: I wanted to show roleTitle instead of roles in the above query.
I am confused how to relate table roles with this query and returns required result
I know it is feasible with coding but i want in SQL.Any suggestion will be appreciated.
SELECT g.groupName,
GROUP_CONCAT(r.roleTitle
ORDER BY FIND_IN_SET(r.roleId, p.roles))
AS RoleTitles
FROM groups AS g
LEFT JOIN preveleges AS p
ON g.groupId = p.groupId
LEFT JOIN roles AS r
ON FIND_IN_SET(r.roleId, p.roles)
GROUP BY g.groupName ;
Tested at: SQL-FIDDLE
I would change the data structure it self. Since It's not normalised, there are multiple elements in a single column.
But it is possible with SQL, if for some (valid) reason you can't change the DB.
A simple "static" solution:
SELECT REPLACE(REPLACE(roles, '1', 'add'), '2', 'edit') from groups
LEFT JOIN preveleges ON(groups.groupId=preveleges.groupId)
A more complex but still ugly solution:
CREATE FUNCTION ReplaceRoleIDWithName (#StringIds VARCHAR(50))
RETURNS VARCHAR(50)
AS
BEGIN
DECLARE #RoleNames VARCHAR(50)
SET #RoleNames = #StringIds
SELECT #RoleNames = REPLACE(#RoleNames, CAST(RoleId AS VARCHAR(50)), roleTitle)
FROM roles
RETURN #RoleNames
END
And then use the function in the query
SELECT ReplaceRoleIDWithName(roles) from groups
LEFT JOIN preveleges ON(groups.groupId=preveleges.groupId)
It is possible without function, but this is more readable. Made without editor so it's not tested in anyway.
You also tagged the question with PostgreSQL and it's actually quite easy with Postgres to work around this broken design:
SELECT grp.groupname, r.roletitle
FROM groups grp
join (
select groupid, cast(regexp_split_to_table(roles, ',') as integer) as role_id
from privileges
) as privs on privs.groupid = grp.groupid
join roles r on r.roleid = privs.role_id;
SQLFiddle: http://sqlfiddle.com/#!12/5e87b/1
(Note that I changed the incorrectly spelled name preveleges to the correct spelling privileges)
But you should really, really re-design your data model!
Fixing your design also enables you to define foreign key constraints and validate the input. In your current model, the application would probably break (just as my query would), if someone inserted the value 'one,two,three' into the roles table.
Edit
To complete the picture, using Postgres's array handling the above could be slightly simplified using a similar approach as MySQL's find_in_set()
select grp.groupname, r.roletitle
from groups grp
join privileges privs on grp.groupid = privs.groupid
join roles r on r.roleid::text = any (string_to_array(privs.roles, ','))
In both cases if all role titles should be shown as a comma separated list, the string_agg() function could be used (which is equivalent to MySQL's group_concat()
select grp.groupname, string_agg(r.roletitle, ',')
from groups grp
join privileges privs on grp.groupid = privs.groupid
join roles r on r.roleid::text = any (string_to_array(privs.roles, ','))
group by grp.groupname
I'm trying to get all the data from the match table, along with the currently signed up gamers of each type, experienced or not.
Gamers
(PK)Gamer_Id
Gamer_firstName,
Gamer_lastName,
Gamer experience(Y/N)
Gamer_matches
(PK)FK GamerId,
(PK)FK MatchId,
Gamer_score
Match
(PK)Match_Id,
ExperiencedGamers_needed,
InExperiencedGamers_needed
I've tried this query along with many others but it doesn't work, is it a bad join?
SELECT M.MatchId,M.ExperiencedGamers_needed,M.InExperiencedGamers_needed,
(SELECT COUNT(GM.GamerId)
FROM Gamers G, Gamers_matches GM
WHERE G.GamerId = GM.GamerId
AND G.experience = "Y"
AND GM.MatchId = M.MatchId
GROUP BY GM.MatchId)AS ExpertsSignedUp,
(SELECT COUNT(GM.GamerId)
FROM Gamers G, Gamers_matches GM
WHERE G.GamerId = GM.GamerId
AND G.experience = "N"
AND GM.MatchId = M.MatchId
GROUP BY GM.MatchId) AS NovicesSignedUp
FROM MATCHES M
What you've written is called a correlated subquery which forces SQL to re-execute the subquery for each row fetched from Matches. It can be made to work, but it's pretty inefficient. In some complex queries it may be necessary, but not in this case.
I would solve this query this way:
SELECT M.MatchId, M.ExperiencedGamers_needed,M.InExperiencedGamers_needed,
SUM(G.experience = 'Y') AS ExpertsSignedUp,
SUM(G.experience = 'N') AS NovicesSignedUp
FROM MATCHES M
LEFT OUTER JOIN (Gamer_matches GM
INNER JOIN Gamers G ON G.GamerId = GM.GamerId)
ON M.MatchId = GM.MatchId
GROUP BY M.MatchId;
Here it outputs only one row per Match because of the GROUP BY at the end.
There's no subquery to re-execute many times, it's just joining Matches to the respective rows in the other tables once. But I use an outer join in case a Match has zero players of eithe type signed up.
Then instead of using COUNT() I use a trick of MySQL and use SUM() with a boolean expression inside the SUM() function. Boolean expressions in MySQL always return 0 or 1. The SUM() of these is the same as the COUNT() where the expression returns true. This way I can get the "count" of both experts and novices only scanning the Gamers table once.
P.S. MySQL is working in a non-standard way to return 0 or 1 from a boolean expression. Standard ANSI SQL does not support this, nor do many other brands of RDBMS. Standardly, a boolean expression returns a boolean, not an integer.
But you can use a more verbose expression if you need to write standard SQL for portability:
SUM(CASE G.experience WHEN 'Y' THEN 1 WHEN 'N' THEN 0 END) AS ExpertsSignedUp