I have two tables, user:
id
full_name
1
Beatriz
2
Mauro
3
Jose
4
fran
approver :
id
subordinate_id
approver_id
1
1
2
2
3
4
I would like to bring up the names of people who are not registered in the subordinate_id column
I did the following query:
SELECT
U.full_name
FROM user AS U
INNER JOIN approver as A
ON U.id <> A.subordinate_id ;
enter image description here
and still users are coming in that are in the subordinate_id column of the approver table.
I would like to get the result only for user names that are not subordinate_id, can someone help with this?
I would like a result with only the users that are not subordinate_id
This is simple to accomplish an ansi-sql with a not exists semi join:
Select full_name
from user u
where not exists (
select * from approver a
where a.approver_id = u.id <-- or (subordinate_id, whichever it should be)
);
Related
I have 2 tables
User:
ID
NAME
1
John
2
Jane
3
Jim
login:
id
date
1
2021-01-29
3
2021-02-27
1
2021-03-11
3
2021-04-18
I want to get the result like:
name
date
John
2021-03-11
Jane
null
Jim
2021-04-18
How shall I write the SQL query?
I tried quite a few join but never got the 2nd record (Jane/Null) out from the query. Need some help here, thanks a ton in advance!
You can use left join and group by:
select u.id, u.name, max(l.date)
from user u left join
login l
on l.id = u.id
group by u.id, u.name;
Note: This includes the id as well. If name is known to be unique that is not necessary.
complimenting #gordons answer another option is to use a subquery like follows
SELECT user.name, login.last_login
FROM user
LEFT JOIN (SELECT id, max(date) AS last_login FROM logins group by id) AS login
ON login.id = user.id
I have two tables (Users and Pairs). The Pairs table contains 3 columns, an ID and then a user1ID and user2ID.
Users
ID firstName surname
------------------------------
1043 john doe
2056 jane doe
Pairs
ID user1ID user2ID
------------------------------
1 1043 2056
I'm then looking at using a select statement to get the user details base on the ID of the Pairs table:
SELECT users1.*, users2.*
FROM Pairs
JOIN Users users1 ON Pairs.user1ID = users1.IDNumber
JOIN Users users2 ON Pairs.user2ID = users2.IDNumber
WHERE Pairs.ID = 1
Which returns the right details for the two users, however they're all on one row, how can I get it to return each user on a separate row as they are in the Users table?
SELECT users1.*, users2.*
FROM Pairs
JOIN Users
ON Pairs.user1ID = users.IDNumber
OR Pairs.user2ID = users.IDNumber
WHERE Pairs.ID = 1
Just use an OR statement in your ON condition instead of 2 joins.
IN will work also.
SELECT *
FROM Pairs p
JOIN Users u ON u.ID IN (p.user1ID, p.User2ID)
WHERE p.ID = 1
I have tables users and topics. Every user can have from 0 to several topics (one-to-many relationship).
How I can get only those users which have at least one topic?
I need all columns from users (without columns from topics) and without duplicates in table users. In last column I need number of topics.
UPDATED:
Should be like this:
SELECT user.*, count(topic.id)
FROM ad
LEFT JOIN topic ON user.id = topic.ad
GROUP BY user.id
HAVING count(topic.id) > 0;
but it takes 0 result. But it should not be 0.
Firstly you need to have your two tables, because you have left limited information about your table structure I will use an example to explain how this works, you should then be able to easily apply this to your own tables.
Firstly you need to have two tables (which you do)
Table "user"
id | name
1 | Joe Bloggs
2 | Eddy Ready
Table "topic"
topicid | userid | topic
1 | 1 | Breakfast
2 | 1 | Lunch
3 | 1 | Dinner
Now asking for a count against each user is done using the follwing;
SELECT user.name, count(topic.topicid)
FROM user
INNER JOIN topic ON user.id = topic.userid
GROUP BY user.name
If you use a left join, this will include records from the "user" table which does not have any rows in the "topic" table, however if you use an INNER JOIN this will ONLY include users who have a matching value in both tables.
I.e. because the user id "2" (which we use to join) is not listed in the topic table you will not get any results for this user.
Hope that helps!
use inner join and distinct
select distinct user_table.id
from user_table
inner join topics_table on topic_table.user_id = user_table.id
select u.id
, u.name
, count(b.topicName)
from user u
left join topic t on t.userid = u.id
group by u.id, u.name
You can select topic number per user and then join it with user data. Something like this:
with t as
(
select userid, count(*) as n
from topic
group by userid
)
SELECT user.*, t.n
FROM user
JOIN t ON user.id = t.userid
Here is the case:
There is a user table
id email orders_counter
=================================
1 a#a.com 5
2 b#b.com 3
3 c#c.com 0
And a user data table for user's other data
id user_id title value
=======================================
1 1 Name Peter Johnson
2 1 Tel 31546988
3 2 Name Alan Johnson
4 2 Tel 56984887
If I want to fetch all user that
1, orders_counter greater then 3
2, Name contain 'Johnson'
3, Tel contain '88'
AT THE SAME TIME
What is my sql, and if I want to do it rubyonrails way
what is the ActiveRecord code
I know I can it one by one and then join all of them together, but it waste too much resource while conditions build up
Select * From `user` u
inner join `userdata` d on d.user_id=u.id and d.title='Name' and d.value like '%Johnson%'
inner join `userdata` c on c.user_id=u.id and c.title='Tel' and c.value like '%88%'
where orders_counter > 3
the way that you've got your user data table structured, you'll almost always have to join on that table several times in order to "pivot" those values into columns. I'd recommend just creating a table that has name and tel as columns. then the query becomes a lot more simple
select * from `user` u
inner join `user_data` d on d.Tel like '%88%' and d.Name like '%johnson%'
where u.orders_counter > 3
try this one up,
SELECT a.*, b.*
FROM user a
INNER JOIN data b
ON a.id = b.user_ID
WHERE a.orders_counter > 3 AND
(b.title = 'NAME' AND b.value like '%johnson%') AND
(b.title = 'TEL' AND b.tel like '%88%')
try this:
select *
from user U join user_data D
on U.id=D.user_id
where U.orders_counter>3
and D.title='Name' and value like '%Johnson%'
and D.title='Tel' and value like '%88%'
I have two tables:
Users: ID, first_name, last_name
Networks: user_id, friend_id, status
I want to select all values from the users table but I want to display the status of specific user (say with id=2) while keeping the other ones as NULL. For instance:
If I have users:
? first_name last_name
------------------------
1 John Smith
2 Tom Summers
3 Amy Wilson
And in networks:
user_id friend_id status
------------------------------
2 1 friends
I want to do search for John Smith for all other users so I want to get:
id first_name last_name status
------------------------------------
2 Tom Summers friends
3 Amy Wilson NULL
I tried doing LEFT JOIN and then WHERE statement but it didn't work because it excluded the rows that have relations with other users but not this user.
I can do this using UNION statement but I was wondering if it's at all possible to do it without UNION.
You need to put your condition into the ON clause of the LEFT JOIN.
Select
u.first_name,
u.last_name,
n.status
From users u
Left Join networks n On ( ( n.user_id = 1 And n.friend_id = u.id )
Or ( n.friend_id = 1 And n.user_id = u.id )
Where u.id <> 1
This should return you all users (except for John Smith) and status friend if John Smith is either friend of this user, or this user is friend of John Smith.
You probably don't need a WHERE clause, and instead of that, put the condition into the "ON" clause that follows your "LEFT JOIN". That should fix your issues. Also, make sure that the main table is on the left side of the left join, otherwise, you should use a right join.
In addition to the (correct) replies above that such conditions should go in the ON clause, if you really want to put them in the WHERE clause for some reason, just add a condition that the value can be null.
WHERE (networks.friendid = 2 OR networks.friendid IS NULL)
From what you've described, it should be a case of joining a subset of networks to users.
select id, first_name, last_name, status
from users u
left join networks n on u.id = n.user_id
and n.friend_id = 1
where id <> 1;
The left join will keep rows from users that do not have a matching row in networks and adding the and n.friend_id = 1 limits when the 'friends' status is returned. Lastly, you may choose to exclude the row from users that you are running the query for.