There are two tables:
TABLE bills
item_id | price
c1 | 10000
m1 | 9000
m2 | 8000
TABLE cars
id | model
1 | toyota
2 | bmw
I need JOIN both tables, where item_id=id AND the first letter in item_id is 'c', so I need to get: c1 | 10000 | 1 | toyota
select *
from cars c
join bills b on b.item_id = concat('c', c.id)
Note that performance is orders of magnitude better (and acceptable) joining in this order, because the calculation to generate the composite key is done once per car, rather than once per car/bill combination had I joined bills first then cars.
Do it like this:
select b.*, c.*
from bills b
inner join cars c on convert(substring(b.item_id, 2, 8000), int) = c.id
where b.item_id like 'c%'
Related
I have these tables in my MySQL database:
BUYERS
ID|SELLER
----------------
0 |Paul
1 |Jean
2 |David
3 |Jack
4 |John
5 |Fred
6 |Peter
PARIS
ID|CAR
---------
0 |Toyota
1 |BMW
2 |Honda
LONDON
ID|CAR
---------
3 |Ford
4 |BMW
5 |Honda
6 |Honda
I use the followinq query :
SELECT b.id, b.seller, p.car
FROM buyers b
JOIN paris p
ON b.id = p.id
UNION ALL
SELECT b.id, b.seller, l.car
FROM buyers b
JOIN london l
ON g.id = l.id;
To get the following result :
ID|SELLER |CAR
----------------
0 |Paul |Toyota
1 |Jean |BMW
2 |David |Honda
3 |Jack |Ford
4 |John |BMW
5 |Fred |Honda
6 |Peter |Honda
I wanted to retrieve rows with "Honda" as "CAR" and I Tried to append the query with "Where car = 'Honda'" but without success..
Thanks for any help
Adding
WHERE car = 'Honda';
to your query only refers to the second query, i.e. the one after UNION ALL.
So either:
SELECT b.id, b.seller, p.car FROM buyers b JOIN paris p ON b.id = p.id
WHERE p.car = 'Honda'
UNION ALL
SELECT b.id, b.seller, l.car FROM buyers b JOIN london l ON b.id = l.id
WHERE p.car = 'Honda'
;
or
SELECT id, seller, car
FROM
(
SELECT b.id, b.seller, p.car FROM buyers b JOIN paris p ON b.id = p.id
UNION ALL
SELECT b.id, b.seller, l.car FROM buyers b JOIN london l ON b.id = l.id
) data
WHERE car = 'Honda';
Just appending WHERE car = 'Honda' is ambiguous. Which car column should be checked?
The easiest way to achieve this is to wrap your existing query within another select statement so that the query is applied on the resulting table, i.e.
SELECT * FROM
(
SELECT b.id, b.seller, p.car
FROM buyers b
JOIN paris p
ON b.id = p.id
UNION ALL
SELECT b.id, b.seller, l.car
FROM buyers b
JOIN london l
ON g.id = l.id;
)
WHERE car = 'Honda'
Can you please try below query:
select * from (
SELECT b.id, b.seller, p.car
FROM buyers b
JOIN paris p
ON b.id = p.id
UNION ALL
SELECT b.id, b.seller, l.car
FROM buyers b
JOIN london l
ON g.id = l.id;
)
where car = 'HONDA'
This is not an answer, but mere advice.
Just in case this is your real database (I'm pretty sure it isn't), here is some advice:
The table names tell us what entities you are dealing with. In your database this is buyers, parises, and londons. You probably see your mistake ;-)
Then looking into the buyers table we see the main column is called seller. What the heck? Is it buyer or seller?
Then a column called ID should be the table's ID and uniquely identify a record in the table. You, however, are using the buyers IDs in other tables and still call them ID.
In your example each buyer has only one other record either in London or in Paris. If this is the case, then you can simply make the car a column in the buyers table instead. If you do need an n:m relation, then call the IDs by what they are, i.e. buyer_id or the like.
In any case there should be a car table containing one record per car, in order to avoid misspellings like 'Homda' in some records.
You are showing car brands, but call the table cars. If it's really about brands only, a better name would hence be brands or car_brands or the like.
Here is an example on how to design the database:
Cars
id_car | name
-------+-------
1 | BMW
2 | Ford
3 | Honda
4 | Toyota
Sellers
id_seller | name
----------+------
0 | Paul
1 | Jean
2 | David
3 | Jack
4 | John
5 | Fred
6 | Peter
Sellers_Cars
id_seller | id_car
----------+-------
0 | 1
0 | 2
0 | 4
1 | 1
2 | 3
3 | 2
4 | 1
5 | 3
6 | 3
6 | 4
A possible query:
select name as honda_seller
from sellers
where id_seller in
(
select id_seller
from sellers_cars
where car_id = (select car_id from cars where name = 'Honda')
);
I believe the answer is already there at stackoverflow but I cannot find the right keywords. So please help.
Table sales looks like this:
state | sales-representative | product | sales
NY | Mike B. | prod-A | 90
FL | David J. | prod-B | 120
FL | Mike B. | prod-A | 15
I need to get the total sales by such sales representative. Expected results for Mike B. look at this:
state | product | sales
NY | prod-A | 90
FL | prod-A | 15
NY | prod-B | 0 <--How can I get this record as well?
FL | prod-B | 0
A regular sum query returns the first 2 records. How can I get the last 2 records as well?
select state, product, sum(sales)
from sales
where sales-representative = 'Mike B.'
group by state, product
SELECT ss.state, sp.product, SUM(sr.sales)
FROM (SELECT DISTINCT state FROM sales) AS ss
CROSS JOIN (SELECT DISTINCT product FROM sales) AS sp
LEFT JOIN sales AS r
AS sr ON ss.state = s.state
AND sp.product = s.product
AND r.`sales-representative` = 'Mike B.'
GROUP BY ss.state, sp.product;
The cross join gets you every combination of state and product, and the left join gets you the specified representative's associated sales.
You can use a left join on subquery for stated and product
select t.state, t.product, sum(sales)
from table1
left join (
select t1.state, t2.product
from t1
cross join (
select product
from t1
) t2
) t on t.state = table1.state and t.product = table1.product
grooup by t.state, t.product
I want to select all the planes that aren't belong to a certain company. I have three tables in this case: Planes, Companies, and CompanyPlanes.
Here is my query:
SELECT *
FROM planes p,
companyplanes cp,
companies c
WHERE c.id = ?
AND cp.idCompany != c.id
AND (cp.idPlane = p.id OR p.id NOT IN (SELECT idPlane FROM companyplanes))
ORDER BY name ASC
But this query returned nothing! what is the wrong here?
example:
| Plane |
---------
id | name
---------
1 | p1
2 | p2
3 | p3
|Company|
---------
id | name
---------
1 | c1
2 | c2
| companyPlanes |
------------------------
id | idCompany | idPlane
------------------------
1 | 1 | 1
2 | 1 | 2
3 | 2 | 2
if I want to get the planes that are not belong to the company c2 the result should be: p1, p3.
Update Answer
We can get the result in following way
Get all planes of the unexpected company
SELECT idplane from CompanyPlanes
WHERE idCompany = ?
Get all planes without those planes of the unexpected company
SELECT * FROM Planes
WHERE id NOT IN
(
SELECT idplane from CompanyPlanes
WHERE idCompany = ?
)
You don't need to join with Company table as you already get idCompany from CompanyPlanes table.
The inner join requires that the query return rows from planes which have a corresponding row in companyplanes but the subselect excludes any rows which have corresponding records in companyplanes.
Assuming that you want the records from planes which don't have a record in companyplanes, then why are you also selecting from companies?
Select p.*
From planes p
Left join
Companyplanes do
On p.id=cp.idplane
Where cp.idplane is null;
If I understand your question the right way, this is what you might be looking for..
select p.*
from planes p
join companyplanes cp on cp.idPlane=p.id
join companies c on c.id=cp.idCompany
where c.id != ?
I need a help about a little confusing sql query. I have 3 tables. Names : article, category and category_article table.
In my article table, there are 4 columns which are :
aid -> article id
py -> Year of article
totalPoint -> point of Article
tc -> number of cited of article
In category table, there are 2 columns which are :
cid -> category id
category -> name of category
Lastly, in my category_article table, there are 2 columns which are :
cid -> category id
aid -> article id related with category
In the below, there are sample table inputs.
Article Table
______________________________
| aid | py | totalPoint | tc |
-------------------------------
| 1 | 2014| 30 | 3 |
-------------------------------
| 2 | 2013| 20 | 2 |
-------------------------------
| 3 | 2014| 50 | 10 |
_______________________________
Category Table
__________________
| cid | category |
-------------------
| 1 | Surgery |
-------------------
| 2 | Enginering|
____________________
Category_Article Table
__________________
| cid | aid |
-------------------
| 1 | 3 |
-------------------
| 2 | 5 |
____________________
My purpose is find this output with only one sql query.
Category name, year, totalArticleNumber, totalPoint(desc), id of article(the most cited article at that year and at that category), citedTime (Top 20)
The example output is :
_______________________________________________________________________________________
Category name | year | totalArticleNumber | totalPoint | id of article(best) | citedTime |
________________________________________________________________________________________
Surgery | 2013 | 182 | 5234 | 312 | 22 |
_________________________________________________________________________________________
Engineering | 2014 | 189 | 5000 | 10 | 32 |
I can do this table with java programing language. Like first do some query and after that do it second query.
But i need to do it in one query.
I try to use JOIN , HAVING , GROUP BY , DISTINCT and anaother some sql stuff but i cannot succeed.
Any help is appreciated.
EDIT
For example if there are two article with same time cited value, they are shown together.
Like in first two column, the article 419 and 385 same time cited value so they both in table.
There are two options for me.
First way -> Show only one article and limit 20. So in this way i can see 20 different category-year combination.
Second way -> Show the same value timecited articles but i have to see 20 different category-year combination.
This is a little tricky, because you're trying to do a lot of different things here. I would simply break them down and put them back together. First, if you want to JOIN all the tables together, you can use the following syntax:
SELECT *
FROM article a
JOIN category_article ca ON ca.aid = a.aid
JOIN category c ON c.cid = ca.cid;
Now, this will only show articles that are assigned to a category. In other words, if an article doesn't exist in the category_article table, or a category doesn't exist in the category_article table, it won't appear here.
If you want to get the total number of articles for a category per year, you can use the COUNT(*) aggregate function, and the SUM() function to get the total points for that category, and then group by category and year to get the amounts for that group:
SELECT c.category, a.py, COUNT(*) AS numArticles, SUM(totalPoint) AS totalPoints
FROM article a
JOIN category_article ca ON ca.aid = a.aid
JOIN category c ON c.cid = ca.cid
GROUP BY c.cid, a.py;
Next, getting the best article will have to be done using a subquery. I recommend focusing just on that subquery for a moment. You can write one query to get the MAX tc for each category and year, and then join that with your table to get all the matching conditions, like this:
SELECT c.category, a.*
FROM category c
JOIN category_article ca ON c.cid = ca.cid
JOIN article a ON a.aid = ca.aid
JOIN(
SELECT c.cid, a.py, MAX(a.tc) AS maxCited
FROM category c
JOIN category_article ca ON ca.cid = c.cid
JOIN article a ON a.aid = ca.aid
GROUP BY c.cid, a.py) temp ON temp.cid = c.cid AND temp.py = a.py AND temp.maxCited = a.tc;
Once you have that, you can JOIN that subquery with the query above to show the best article information alongside the other group information.
SELECT temp1.category, temp1.py, temp1.numArticles, temp1.totalPoints, temp2.aid AS bestArticle, temp2.tc AS citedTime
FROM(
SELECT c.category, a.py, COUNT(*) AS numArticles, SUM(totalPoint) AS totalPoints
FROM article a
JOIN category_article ca ON ca.aid = a.aid
JOIN category c ON c.cid = ca.cid
GROUP BY c.cid, a.py) temp1
JOIN(
SELECT c.category, a.*
FROM category c
JOIN category_article ca ON c.cid = ca.cid
JOIN article a ON a.aid = ca.aid
JOIN(
SELECT c.cid, a.py, MAX(a.tc) AS maxCited
FROM category c
JOIN category_article ca ON ca.cid = c.cid
JOIN article a ON a.aid = ca.aid
GROUP BY c.cid, a.py) temp ON temp.cid = c.cid AND temp.py = a.py AND temp.maxCited = a.tc) temp2
ON temp1.category = temp2.category AND temp1.py = temp2.py;
Here is an SQL Fiddle example. I am going to play around with how to use fewer JOINS, but for right now it should give you what you want and since your tables are indexed it shouldn't run too slowly.
I have two tables: 'company' and 'order'. The first one contains company info and the second one holds all orders made with a company. (order.company = company.ID).
I am making a query on the first table, for example all companies in the city of New York. I would like to make a join with the order table, so that it immediately shows how many orders for a company was made. I could do this with a simple JOIN query, however, it does not include 0. For example, if a company has no orders yet, it will not show up at all, while it should be in the list with 0 orders.
Desired end result:
----------------------------------------
| ID | Name | ... | Orders |
----------------------------------------
| 105 | Company A | ... | 14 |
| 115 | Company B | ... | 5 |
| 120 | Company C | ... | 0 |
| 121 | Company D | ... | 0 |
----------------------------------------
Thanks in advance!
This is a left join with aggregation:
SELECT c.ID, c.Name, count(o.company) as total
FROM companies c left outer join
orders o
on c.id = o.company
WHERE c.city = 'New York'
GROUP BY c.ID;
In MySQL, it is best to avoid subqueries in the from clause -- where possible -- because the derived table is actually created.
The COUNT() expression is counting the number of matches by counting the number of non-null values in the id field used for the join.
Try this
SELECT com.id,com.name,od.orders FROM compnay AS com
LEFT JOIN orders AS od ON od.company = com.id;
SELECT companies.ID,companies.Name ,orders.total FROM
(SELECT ID,Name FROM company where county ='NEW YORK') companies
LEFT JOIN (SELECT company,COUNT(*) as total FROM order GROUP BY company) orders
ON orders.company = companies.ID