I've got the following table layouts:
Table Data
+----------+-------------------------+
| Field | Type |
+----------+-------------------------+
| type | enum('type_b','type_a') |
| type_id | int(11) unsigned |
| data | bigint(20) unsigned |
+----------+-------------------------+
Table A and B:
+--------------+------------------+
| Field | Type |
+--------------+------------------+
| id | int(11) unsigned |
| customer_id | int(11) unsigned |
| ... |
+--------------+------------------+
In table Data there is some messurement data from a certain type (a or b).
Now I want for ever customer the total sum for both types of data a and b.
So, I thought: select the sum, join on a or b and group by a.customer_id, b.customer_id.
Resulting in the following query:
SELECT sum(d.data) as total
FROM data d, ta, tb
WHERE
(d.type LIKE "type_a" AND d.type_id = ta.id)
OR
(d.type LIKE "type_b" AND d.type_id = tb.id)
GROUP BY ta.customer_id, tb.customer_id;
This doesn't get me the proper results...
I tried several approaches, left joins, joining on the customer table and group by customer.id etc. Does anyone have a clue what I'm doing wrong?
Thanx!
Your query
SELECT sum(d.data) as total
FROM data d, ta, tb
WHERE
(d.type LIKE "type_a" AND d.type_id = ta.id)
OR
(d.type LIKE "type_b" AND d.type_id = tb.id)
GROUP BY a.customer_id, b.customer_id;
Let's say there is only one record in d, and it is type_a. There are two records in ta and tb each. The record in d matches one of the records in ta on d.type_id=ta.id. Therefore, that combination of (d x ta) allows ANY tb record to remain in the final result. You get an unintended cartesian product.
SELECT x.customer_id, SUM(data) total
FROM
(
SELECT ta.customer_id, d.data
FROM data d JOIN ta
ON (d.type LIKE "type_a" AND d.type_id = ta.id)
UNION ALL
SELECT tb.customer_id, d.data
FROM data d JOIN tb
ON (d.type LIKE "type_b" AND d.type_id = tb.id)
) X
GROUP BY x.customer_id;
Related
I want to fetch data from two table and apply arithmetic operation on the column.
This is wha I tried :
String sql = "SELECT SUM(S.san_recover-C.amount) as total
FROM sanction S
LEFT JOIN collection C ON S.client_id = C.client_id
WHERE S.client_id=?";
This code is working only when there is value in both tables, but if there is no value in one of two tables there is no result.
SELECT SUM(S.san_recover - C.amount) as total
FROM sanction S
LEFT JOIN collection C ON S.client_id = C.client_id
WHERE S.client_id = ?
The problem with your query lies in the SUM() function. When the left join does not bring back records, then c.amount is NULL. When substracting NULL from something, you get a NULL result, which then propagates across the computation, and you end up with a NULL result for the SUM().
You probably want COALESCE(), like so:
SELECT SUM(S.san_recover - COALESCE(C.amount, 0)) as total
FROM sanction S
LEFT JOIN collection C ON S.client_id = C.client_id
WHERE S.client_id = ?
Where there is a possibility that a client may exist in one table but no another a full join would be appropriate but since mysql does not have such a thing then a union in a sub query will do
drop table if exists sanctions,collections;
create table sanctions(client_id int, amount int);
create table collections(client_id int, amount int);
insert into sanctions values
(1,10),(1,10),(2,10);
insert into collections values
(1,5),(3,10);
Select sum(Samount - camount)
From
(Select sum(amount) Samount, 0 as camount from sanctions where client_id =3
Union all
Select 0,sum(amount) as camount from collections where client_id =3
) s
;
+------------------------+
| sum(Samount - camount) |
+------------------------+
| -10 |
+------------------------+
1 row in set (0.00 sec)
If you want to do this for all clients
Select client_id,sum(Samount - camount) net
From
(Select client_id,sum(amount) Samount, 0 as camount from sanctions group by client_id
Union all
Select client_id,0,sum(amount) as camount from collections group by client_id
) s
group by client_id
;
+-----------+------+
| client_id | net |
+-----------+------+
| 1 | 15 |
| 2 | 10 |
| 3 | -10 |
+-----------+------+
3 rows in set (0.00 sec)
I would like to ask for help for an SQL request that give me values from two tables.
As an example I have one Table orders und one table processing.
I would like to make an report of the orders and the state of processing.
table orders
id | status | div
-------------------
1 | wating_r | div1
2 | closed | div2
3 | closed | div3
-
table processing:
id | order_id | type | date
----------------------------------------
1 | 2 | send_request | 15.01.15
2 | 2 | send_invoice | 30.01.15
3 | 1 | send_request | 01.02.15
4 | 3 | send_request2 | 10.02.15
5 | 3 | send_invoice | 15.02.15
what I would like to get:
order_id | status | date_request | date_request2 | date_invoice
--------------------------------------------------------------------------------
1 | waiting_r | 01.02.15 | NULL | NULL
2 | closed | 15.01.15 | NULL | 30.01.15
3 | closed | NULL | 10.02.15 | 15.02.15
my solution:
select orders.id as order_id, orders.status, IF(processing.type='send_invoice',date_format(processing.date, '%Y-%m-%d'), NULL) as date_invoice, IF(processing.type='send_request',date_format(processing.date, '%Y-%m-%d'), NULL) as date_request, IF(processing.type='send_request2',date_format(processing.date, '%Y-%m-%d'), NULL) as date_request2
from orders
inner join processing on orders.id = processing.order_id
where
case
when orders.status='closed' then processing.type='send_invoice'
when orders.status='waiting_r' then processing.type='send_request'
when orders.status='waiting_2'then processing.type='send_request2'
end
This works fine but with this IF statements I doesn't become the dates from the requests when an invoice was sent - I only get the date of the invoice.
Instead of the case request I tried the following but in this case I have more than one line for every order. When I tried to "group by" I have mixed data.
where
processing.type in ('send_invoice', 'send_request', 'completion_request_send')
You need to left-join the second table to the first three times, like so.
SELECT o.id AS order_id, o.status,
p1.date AS date_request,
p2.date AS date_request2,
p3.date AS date_invoice
FROM orders o
LEFT JOIN processing p1 ON o.id = p1.order_id AND p1.type='send_request'
LEFT JOIN processing p2 ON o.id = p2.order_id AND p2.type='send_request2'
LEFT JOIN processing p3 ON o.id = p3.order_id AND p3.type='send_invoice'
ORDER BY 1,2
This left-join with an id-matching criterion and the specific type choice pulls out the rows you need for each column. Left, as opposed to inner, join, allows the missing values to be shown as null.
Here it is, working. http://sqlfiddle.com/#!9/b8c74/5/0
This is a typical pattern for joining a key/value table where the (id/key) pairs are unique.
Edit Unfortunately it generates duplicate result set rows in situations where there's a duplicate key for a particular value. To deal with that, it's necessary to deduplicate the key/value table (processing) in this case.
This subquery will do that, taking the latest date value.
SELECT type, order_id, MAX(date) AS date
FROM processing
GROUP BY type, order_id
Then you have to use that subquery in the main query. This is where it would be good if MySQL had common table expressions. But it doesn't so things get kind of verbose.
SELECT o.id AS order_id, o.status,
p1.date AS date_request,
p2.date AS date_request2,
p3.date AS date_invoice
FROM orders o
LEFT JOIN (
SELECT type, order_id, MAX(date) AS date
FROM processing
GROUP BY type, order_id
) p1 ON o.id = p1.order_id AND p1.type='send_request'
LEFT JOIN (
SELECT type, order_id, MAX(date) AS date
FROM processing
GROUP BY type, order_id
) p2 ON o.id = p2.order_id AND p2.type='send_request2'
LEFT JOIN (
SELECT type, order_id, MAX(date) AS date
FROM processing
GROUP BY type, order_id
) p3 ON o.id = p3.order_id AND p3.type='send_invoice'
ORDER BY 1,2
I have the following tables
1. tblJobs
JobID int primary key
JobTypeID int
JobClientID int
JobStaffID int
....
2. tblContacts
ContactID int primary key
ContactName varchar
....
3. tblJobTypes
TypeID int primary key
TypeName varchar
I can SELECT data from these table with this SQL...
SELECT tblContacts.ContactName, tblContacts.ContactID,
tblJobs.JobID, tblJobs.JobTypeID, tblJobs.JobClientID, tblJobs.JobStaffID,
tblJobTypes.* FROM (tblJobs LEFT JOIN tblJobTypes ON tblJobs.JobTypeID = tblJobTypes.TypeID) LEFT JOIN tblContacts ON tblJobs.JobClientID = tblContacts.ContactID;
An example row from the SQL...
| ContactName| ContactID | JobID | JobTypeID | JobClientID | JobStaffID |TypeID | TypeName |
| Mr Contact | 290 | 341 | 3 | 290 | 202 | 3 | Enquiry |
As you can see this SQL joins the tblJobs.JobClientID to tblContacts.ContactID(290).
This is how I get tblContacts.JobStaffID (202).
How can I modify the SQL to get tblContacts.ContactName?
I've tried joining tables twice but with no success.
Assuming that JobStaffID is a foreign key relating to tblContacts.ContactID you're correct in assuming that you need to join the tblContacts table twice - but you have to give it different aliases in each join like this:
SELECT
c1.ContactName as ClientName, c1.ContactID as ClientID,
c2.ContactName as StaffName, c2.ContactID as StaffID,
j.JobID, j.JobTypeID, j.JobClientID, j.JobStaffID,
jt.TypeID, jt.TypeName
FROM tblJobs j
LEFT JOIN tblJobTypes jt ON j.JobTypeID = jt.TypeID
LEFT JOIN tblContacts c1 ON j.JobClientID = c1.ContactID
LEFT JOIN tblContacts c2 ON j.JobStaffID = c2.ContactID;
And while at it you might want to use aliases for all tables to reduce the query text.
Let's say i've got this database:
book
| idBook | name |
|--------|----------|
| 1 |Book#1 |
category
| idCateg| category |
|--------|----------|
| 1 |Adventures|
| 2 |Science F.|
book_categ
| id | idBook | idCateg | DATA |
|--------|--------|----------|--------|
| 1 | 1 | 1 | (null) |
| 2 | 1 | 2 | (null) |
I'm trying to select only the books which are in category 1 AND category 2 something like this
SELECT book.* FROM book,book_categ
WHERE book_categ.idCateg = 1 AND book_categ.idCateg = 2
Obviously, this giving 0 results becouse each row has only one idCateg it does work width OR but the results are not what I need. I've also tried to use a join, but I just can't get the results I expect.
Here it's the SQLFiddle of my current project, with my current DB, the data at the begining is just a sample. SQLFiddle
Any help will be really appreciated.
Solution using EXISTS:
select *
from book b
where exists (select 'x'
from book_categ x
where x.idbook = b.idbook
and x.idcateg = 1)
and exists (select 'x'
from book_categ x
where x.idbook = b.idbook
and x.idcateg = 2)
Solution using join with an inline view:
select *
from book b
join (select idbook
from book_categ
where idcateg in (1, 2)
group by idbook
having count(*) = 2) x
on b.idbook = x.idbook
You could try using ALL instead of IN (if you only want values that match all criteria to be returned):
SELECT book.*
FROM book, book_categ
WHERE book_categ.idCateg = ALL(1 , 2)
One way to get the result is to do join to the book_categ table twice, something like
SELECT b.*
FROM book b
JOIN book_categ c1
ON c1.book_id = b.id
AND c1.idCateg = 1
JOIN book_categ c2
ON c2.book_id = b.id
AND c2.idCateg = 2
This assumes that (book_id, idCateg) is constrained to be unique in the book_categ table. If it isn't unique, then this query can return duplicate rows. Adding a GROUP BY clause or the DISTINCT keyword will eliminate any generated duplicates.
There are several other queries that can get generate the same result.
For example, another approach to finding book_id that are in two categories is to get all the rows with idCateg values of 1 or 2, and then GROUP BY book_id and get a count of DISTINCT values...
SELECT b.*
FROM book b
JOIN ( SELECT d.book_id
FROM book_categ d
WHERE d.idCateg IN (1,2)
GROUP BY d.book_id
HAVING COUNT(DISTINCT d.idCateg) = 2
) c
ON c.book_id = b.id
I have a big table with more than 10,000 rows and it will grow to 1,000,000 in the near future, and I need to run a query which gives back a Time value for each keyword for each user. I have one right now which is quite slow because I use left joins and it needs one subquery / keyword:
SELECT rawdata.user, t1.Facebook_Time, t2.Outlook_Time, t3.Excel_time
FROM
rawdata left join
(SELECT user, sec_to_time(SuM(time_to_sec(EndTime-StartTime))) as 'Facebook_Time'
FROM rawdata
WHERE MainWindowTitle LIKE '%Facebook%'
GROUP by user)t1 on rawdata.user = t1.user left join
(SELECT user, sec_to_time(SuM(time_to_sec(EndTime-StartTime))) as 'Outlook_Time'
FROM rawdata
WHERE MainWindowTitle LIKE '%Outlook%'
GROUP by user)t2 on rawdata.user = t2.user left join
(SELECT user, sec_to_time(SuM(time_to_sec(EndTime-StartTime))) as 'Excel_Time'
FROM rawdata
WHERE MainWindowTitle LIKE '%Excel%'
GROUP by user)t3 on rawdata.user = t3.user
The table looks like this:
WindowTitle | StartTime | EndTime | User
------------|-----------|---------|---------
Form1 | DateTime | DateTime| user1
Form2 | DateTime | DateTime| user2
... | ... | ... | ...
Form_n | DateTime | DateTime| user_n
The output should looks like this:
User | Keyword | SUM(EndTime-StartTime)
-------|-----------|-----------------------
User1 | 'Facebook'| 00:34:12
User1 | 'Outlook' | 00:12:34
User1 | 'Excel' | 00:43:13
User2 | 'Facebook'| 00:34:12
User2 | 'Outlook' | 00:12:34
User2 | 'Excel' | 00:43:13
... | ... | ...
User_n | ... | ...
And the question is, which is the fastest way in MySQL to do this?
I think your wildcard searches are probably what's slowing it down the most, since you can't really utilize indexes on those fields. Also if you can avoid doing sub-queries and just do a straight join, it might help, but the wildcard searches are far worse. Is there anyway you could change the table to have a categoryName or categoryID that can have an index and not require a wildcard search? Like "where categoryName = 'Outlook'"
To optimize the data in your tables, add a categoryID (ideally this would reference a separate table, but let's just use arbitrary numbers for this example):
alter table rawData add column categoryID int not null
alter table rawData add index (categoryID)
Then populate the categoryID field for the existing data:
update rawData set categoryID=1 where name like '%Outlook%'
update rawData set categoryID=2 where name like '%Facebook%'
-- etc...
Then change your insert to follow the same rules.
Then make your SELECT query like this (changed wild cards to categoryID):
SELECT rawdata.user, t1.Facebook_Time, t2.Outlook_Time, t3.Excel_time
FROM
rawdata left join
(SELECT user, sec_to_time(SuM(time_to_sec(EndTime-StartTime))) as 'Facebook_Time'
FROM rawdata
WHERE categoryID = 2
GROUP by user)t1 on rawdata.user = t1.user left join
(SELECT user, sec_to_time(SuM(time_to_sec(EndTime-StartTime))) as 'Outlook_Time'
FROM rawdata
WHERE categoryID = 1
GROUP by user)t2 on rawdata.user = t2.user left join
(SELECT user, sec_to_time(SuM(time_to_sec(EndTime-StartTime))) as 'Excel_Time'
FROM rawdata
WHERE categoryID = 3
GROUP by user)t3 on rawdata.user = t3.user