usertable
----
id, username
grouptable
----
id, groupname
group_user
--------
uid, gid
books
----
id, groupname
Input parameters: groupname, username
output: list of books
Is it possible to use 1 sql statement to get list of books when username is inside groupname
Question 2: any good book to recommand to master complex sql statement..
This query gives list of books by user parametar
SELECT b.id,
FROM usertable u
INNER JOIN group_user gu ON gu.uid = u.id
INNER JOIN grouptable g ON g.id= gu.gid
INNER JOIN books b ON b.groupname = g.groupname
WHERE u.username = #user_name
Also i think if you have the group name you can use
SELECT b.id,
FROM grouptable g
INNER JOIN books b ON b.groupname = g.groupname
WHERE g.groupname = #group_name
Bus having select on both parameters i think is not very good think. This query will get
list of books for user group name
SELECT b.id,
FROM usertable u
INNER JOIN group_user gu ON gu.uid = u.id
INNER JOIN grouptable g ON g.id= gu.gid
AND g.group_name = #group_name
INNER JOIN books b ON b.groupname = g.groupname
WHERE u.username = #user_name
Related
Example tables
taccount
tuser
tproject
What I want to achieve:
accountName count(u.id) count(p.id)
-----------------------------------
Account A 1 1
Account B 1 1
Account C 2 3
In other words I want a single query to join these tables together and count user's and project's per account
I tried:
SELECT
a.name as "accountName",
count(u.name),
count(p.id)
FROM "taccount" a
INNER JOIN "tuser" u ON u.account_id = a.id
INNER JOIN "tproject" p ON p.admin_id = u.id
GROUP BY u.name, a.name, p.id
But it's not grouping by account. It's giving me the following result
Any advice?
You can try below
SELECT
a.name as "accountName",
count(distinct u.name),
count(p.id)
FROM "taccount" a
INNER JOIN "tuser" u ON u.account_id = a.id
INNER JOIN "tproject" p ON p.admin_id = u.id
GROUP BY a.name
When you do Aggregate Function and If there are Column are not do Aggregate you must put in your Group By, because Aggregate functions perform a calculation on a set of rows and return a single row.
SELECT
a.name as "accountName",
count(distinct u.name),
count(p.id)
FROM
"taccount" a
INNER JOIN "tuser" u ON u.account_id = a.id
INNER JOIN "tproject" p ON p.admin_id = u.id
GROUP BY
a.name
So you need just Group By your column "accountName"
change your group by column name
SELECT
a.name as "accountName",
count(distinct u.account_id),
count(p.id)
FROM "taccount" a
INNER JOIN "tuser" u ON u.account_id = a.id
INNER JOIN "tproject" p ON p.admin_id = u.id
GROUP BY a.name
this will work:
select a.name,count(u.id),count(p.id) from
taccount a,tuser b, tproject where
a.id=b.account_id and
b.id=c.admin_id
group by a.name;
I have dbo.Users tables
Id, Name
1, John
2, Mary
3, Michael
Then I have dbo.Phones table
Id, Phonenumber
10, 1234
11, 5555
Then I have dbo.Relationship table
Id, ChildId
1, 10
2, 11
How could I make a query that returns
Id, Name, Phonenumber
1, John, 1234
2, Mary, 5555
3, Michael, NULL
This is what I got so far.
SELECT u.Id, u.Name, p.Phonenumber
FROM dbo.Users as u
LEFT JOIN dbo.Phones as p
-- Something
SQL Fiddle
Think of the Relationship table as the middle-man between your Users and Phones tables here. It is a many-to-many relationship with a mapping table. Join your Users to the Relationship and then the Relationship to your Phones.
SELECT u.Id
,u.Name
,p.PhoneNumber
FROM dbo.Users u
LEFT JOIN dbo.Relationship r ON r.Id = u.Id
LEFT JOIN dbo.Phones p ON p.Id = r.ChildId
Think of it like:
Users: Hello Relationship, I have UserId = 1, what PhoneIds do I have for that UserId?
Relationship: Hi Users. I have PhoneId = 10 for you. I'll go talk to Phones to see what the number is.
Phones: Hi Relationships! I have PhoneNumber 1234 for you. It matches the PhoneId you gave me.
Join them on id field.I would use inner join depending on the requirement
SELECT distinct u.Id, u.Name, p.Phonenumber
FROM dbo.Users as u
LEFT JOIN dbo.Phones as p on u.id = p.id
or---
SELECT distinct u.Id, u.Name, p.Phonenumber
FROM dbo.Users as u
inner join T JOIN dbo.Phones as p on u.id = p.id
inner join dbo.relationship r on r.id = u.id
where----
try this :
Select u.Id, u.Name, p.Phonenumber
From
Users u
Left join Relationship r on r.Id = u.Id
Left join Phones p on r.ChildId = p.Phonenumber
I have tables user, participant and chat. I need to get all users in a specific chat and amount of chats that user in by chat name. For example current tables:
user chat participant
id|name id|name user_id|chat_id
1|Mike 1|School 1|1
2|John 2|Football 2|1
3|Sara 3|Gym 1|2
3|3
And by keyword "School" I want to get this
Mike|2
John|1
I have two queries to get first and second column in result but don't know how to combine it:
SELECT user.name FROM user
JOIN participant ON (user.id = participant.user_id)
JOIN chat ON (participant.chat_id = chat.id) WHERE chat.name = 'School';
That gives me
Mike
John
And
SELECT user.name, COUNT(*) FROM user
JOIN participant ON (user.id = participant.user_id) GROUP BY user.name;
returns
John|1
Mike|2
Sara|1
So how to combine it?
TRY THIS
SELECT p1.name, COUNT(p.user_id) totUser
FROM participant p
INNER JOIN (select u.id, u.name FROM participant p
inner JOIN chat c ON c.id = p.[chat_id]
INNER JOIN user u ON u.id = p.user_id
AND c.name = 'School') p1 ON p1.id = p.user_id
GROUP BY p1.name
using Subquery and joins :
select u.name,count(p.chat_id) as 'Count' from user u
inner join participant p on p.user_id = u.id
where
p.user_id in ( select user_id from participant pp inner join chat cc on cc.id = pp.chat_id where
cc.name = 'School' )
group by u.name
order by Count desc
Output :
I am aware that I am asking something that may look trivial but I could not find and answer or a duplicate. (I am new with this area).
So i am trying.
I have two tables
Tests table with the following columns
1. storyID , authorID , assigneeID
2. userID , userName
I would like to write a query that return storyID, UserName of author ID, UserName of assigneeID.
SELECT storyID, u1.userName AS authorName, u2.userName AS assigneeName
FROM storytable s
INNER JOIN usertable u1 ON s.authorID = u1.userID
INNER JOIN usertable u2 ON s.assigneeID = u2.userID
The above solution will only work in case you have relation between userID, assigneeID and authorID fields.
Select and create an alias for the second table.
SELECT a.storyID, b.userName, c.userName
FROM tablea a
INNER JOIN tableb b ON a.authorID = b.userID
INNER JOIN tableb c ON a.assigneeID= c.userID
Assuming the authorID = UserId...
select
1.storyId,
author.userName,
assignee.userName
from 1
inner join 2 as author
on 1.authorId = 2.userId
inner join 2 as assignee
on 1.assigneeID = 2.userID
I have two tables:
users attributes
id|name id|name|user_id
------- ---------------
1 |foo 1 |bla | 1
2 |bar 1 |blub| 1
1 |bla | 2
How do I create a query gives users with both the "bla" AND "blub" attributes?
In this case it should only return the user "foo".
I know that the data is not normalized.
SELECT u.*, a.id, b.Id, a.name, b.name FROM users u
JOIN attributes a
ON a.User_id = u.User_id AND a.name = 'bla'
JOIN attributes b
ON u.User_Id = b.User_id AND b.name = 'blub'
Assuming an attribute association to a user is unique...
if you need 3 conditions to be true add the conditions to the in and adjust count up 1.
SELECT u.name
FROM users u
INNER JOIN attributes a on A.user_Id = u.id
WHERE a.name in ('bla','blub')
GROUP by u.name
HAVING count(*)=2
and if you don't have an unique association, or you need to join to another table you could always do...
SELECT u.name
FROM users u
INNER JOIN attributes a on A.user_Id = u.id
WHERE a.name in ('bla','blub')
GROUP by u.name
HAVING count(distinct A.name)=2
for a slight performance hit. but this allows you to join and get back additional fields which others have indicated was a detriment to this method.
This allows for scaling of the solution instead of incurring the cost of joining each time to different tables. In addition, if you needed thirty-something values to associate, you may run into restrictions on the number of allowed joins.
SELECT U.NAME
FROM USERS U
INNER JOIN
ATTRIBUTES A1
ON U.ID = A1.USER_ID
INNER JOIN
ATTRIBUTES A2
ON U.ID = A2.USER_ID
WHERE A1.NAME = 'bla'
AND A2.NAME = 'blub'
You can use the INTERSECT operator
SELECT
u.id
,u.name
FROM users AS u
INNER JOIN attributes AS a
ON u.id = a.user_id
WHERE a.name = 'bla'
INTERSECT
SELECT
u.id
,u.name
FROM users AS u
INNER JOIN attributes AS a
ON u.id = a.user_id
WHERE a.name = 'blub'
;
Here is a demo on SQL Fiddle: http://sqlfiddle.com/#!6/68986/5
More info on SET operations in SQL: http://en.wikipedia.org/wiki/Set_operations_(SQL)
SELECT u.name
FROM attributes a
JOIN users u
ON u.id = a.user_id
WHERE a.name IN ('bla','bulb')