I have tables like:
'profile_values'
userID | fid | value
-------+---------+-------
1 | 3 | joe#gmail.com
1 | 45 | 203-234-2345
3 | 3 | jane#gmail.com
1 | 45 | 123-456-7890
And:
'users'
userID | name
-------+-------
1 | joe
2 | jane
3 | jake
I want to join them and have one row with two of the values like:
'profile_values'
userID | name | email | phone
-------+-------+----------------+--------------
1 | joe | joe#gmail.com | 203-234-2345
2 | jane | jane#gmail.com | 123-456-7890
I have solved it but it feels clumsy and I want to know if there is a better way to do it. Meaning solutions that are either more readable or faster(optimized) or simply best-practice.
Current solution: multiple tables selected, many conditional statements:
SELECT u.userID AS memberid,
u.name AS first_name,
pv1.value AS fname,
pv2.value as lname
FROM users AS u,
profile_values AS pv1,
profile_values AS pv2,
WHERE u.userID = pv1.userID
AND pv1.fid = 3
AND u.userID = pv2.userID
AND pv2.fid = 45;
Thanks for the help!
It's a typical pivot query:
SELECT u.userid,
u.name,
MAX(CASE WHEN pv.fid = 3 THEN pv.value ELSE NULL END) AS email,
MAX(CASE WHEN pv.fid = 45 THEN pv.value ELSE NULL END) AS phone,
FROM USERS u
JOIN PROFILE_VALUES pv ON pv.userid = u.userid
GROUP BY u.userid, u.name
Add "LEFT" before the "JOIN" if you want to see users who don't have any entries in the PROFILE_VALUES table.
I didn't say this, which I should have (#OMG Ponies) but I wanted to use this within a MySQL view. And for views to be editable you're not allowed to use aggregate functions and other constraints. So what I had to do whas use the same SQL query as I had described in the initial question.
Hope this helps someone, adding tag for creating views.
Related
I Have a query that finds a table, here's an example one.
Name |Age |Hair |Happy | Sad |
Jon | 15 | Black |NULL | NULL|
Kyle | 18 |Blonde |YES |NULL |
Brad | 17 | Blue |NULL |YES |
Name and age come from one table in a database, hair color comes from a second which is joined, and happy and sad come from a third table.My goal would be to make the first line of the chart like this:
Name |Age |Hair |Happy |Sad |
Jon | 15 |Black |Yes |Yes |
Basically I want to get rid of the rows under the first and get the non NULL data joined to the right. The problem is that there is no column where the Yes values are on the Jon row, so I have no idea how to get them there. Any suggestions?
PS. With the data I am using I can't just put a 'YES' in the 'Jon' row and call it a day, I would need to find the specific value from the lower rows and somehow get that value in the boxes that are NULL.
Do you just want COALESCE()?
COALESCE(Happy, 'Yes') as happy
COALESCE() replaces a NULL value with another value.
If you want to join on a NULL value work with nested selects. The inner select gets an Id for NULLs, the outer select joins
select COALESCE(x.Happy, yn_table.description) as happy, ...
from
(select
t1.Happy,
CASE WHEN t1.Happy is null THEN 1 END as happy_id
from t1 ...) x
left join yn_table
on x.xhappy_id = yn_table.id
If you apply an ORDER BY to the query, you can then select the first row relative to this order with WHERE rownum = 1. If you don't apply an ORDER BY, then the order is random.
After reading your new comment...
the sense is that in my real data the yes under the other names will be a number of a piece of equipment. I want the numbers of the equipment in one row instead of having like 8 rows with only 4 ' yes' values and the rest null.
... I come to the conclusion that this a XY problem.
You are asking about a detail you think will solve your problem, instead of explaining the problem and asking how to solve it.
If you want to store several pieces of equipment per person, you need three tables.
You need a Person table, an Article table and a junction table relating articles to persons to equip them. Let's call this table Equipment.
Person
------
PersonId (Primary Key)
Name
optional attributes like age, hair color
Article
-------
ArticleId (Primary Key)
Description
optional attributes like weight, color etc.
Equipment
---------
PersonId (Primary Key, Foreign Key to table Person)
ArticleId (Primary Key, Foreign Key to table Article)
Quantity (optional, if each person can have only one of each article, we don't need this)
Let's say we have
Person: PersonId | Name
1 | Jon
2 | Kyle
3 | Brad
Article: ArticleId | Description
1 | Hat
2 | Bottle
3 | Bag
4 | Camera
5 | Shoes
Equipment: PersonId | ArticleId | Quantity
1 | 1 | 1
1 | 4 | 1
1 | 5 | 1
2 | 3 | 2
2 | 4 | 1
Now Jon has a hat, a camera and shoes. Kyle has 2 bags and one camera. Brad has nothing.
You can query the persons and their equipment like this
SELECT
p.PersonId, p.Name, a.ArticleId, a.Description AS Equipment, e.Quantity
FROM
Person p
LEFT JOIN Equipment e
ON p.PersonId = e.PersonId
LEFT JOIN Article a
ON e.ArticleId = a.ArticleId
ORDER BY p.Name, a.Description
The result will be
PersonId | Name | ArticleId | Equipment | Quantity
---------+------+-----------+-----------+---------
3 | Brad | NULL | NULL | NULL
1 | Jon | 4 | Camera | 1
1 | Jon | 1 | Hat | 1
1 | Jon | 5 | Shoes | 1
2 | Kyle | 3 | Bag | 2
2 | Kyle | 4 | Camera | 1
See example: http://sqlfiddle.com/#!4/7e05d/2/0
Since you tagged the question with the oracle tag, you could just use NVL(), which allows you to specify a value that would replace a NULL value in the column you select from.
Assuming that you want the 1st row because it contains the smallest age:
- wrap your query inside a CTE
- in another CTE get the 1st row of the query
- in another CTE get the max values of Happy and Sad of your query (for your sample data they both are 'YES')
- cross join the last 2 CTEs.
with
cte as (
<your query here>
),
firstrow as (
select name, age, hair from cte
order by age
fetch first row only
),
maxs as (
select max(happy) happy, max(sad) sad
from cte
)
select f.*, m.*
from firstrow f cross join maxs m
You can try this:
SELECT A.Name,
A.Age,
B.Hair,
C.Happy,
C.Sad
FROM A
INNER JOIN B
ON A.Name = B.Name
INNER JOIN C
ON A.Name = B.Name
(Assuming that Name is the key columns in the 3 tables)
What's a query that I can use to get a list of all logins associated with each user in SQL Azure?
So far I've found the following two queries to get all users and all logins, but I haven't found any way to see which user goes with which login:
SELECT * from sys.sql_logins -- get all logins
SELECT * from sys.sysusers -- get all users
In case you find it helpful, here's the documentation for the structures of those the tables:
sys.sql_logins:
https://msdn.microsoft.com/en-us/library/ms174355.aspx?f=255&MSPPError=-2147217396
Column names: name, principal_id, sid, type, type_desc, is_disabled, create_date, modify_date, default_database_name, default_language_name, credential_id, is_policy_checked, is_expiration_checked, password_hash
sys.sysusers: https://msdn.microsoft.com/en-us/library/ms179871.aspx
Column names: uid, status, name, sid, roles, createdate, updatedate, altuid, password, gid, environ, hasdbaccess, islogin, isntname, isntgroup, isntuser, issqluser, isaliased, issqlrole, isapprole
It's hard to tell you your correct answer b/c we don't know the structure of your tables. If you share that we can help more. But below should get you to where you need to go.
They way to do it is by a MySQL JOIN. In this case you should use a INNER or OUTER JOIN depending on how your database is structured.
If you have 2 tables that are structured below you can do an FULL OUTER JOIN
[sys.sql_logins]
| sid| userID | name |
| 1 | 1 | ssmith |
| 2 | 2 | bbob |
[sys.sysusers]
| sid| name |
| 1 | Sam Smith |
| 2 | Billy Bob |
You can use the following query to do it
SELECT A.name as userName, B.name as login
FROM sys.sysusers A
FULL OUTER JOIN sys.sql_logins B
ON A.sid = B.sid
This will result in :
| userName | logins |
| Same Smith | ssmith |
| Billy Bob | bbob |
Here is a link to more types of MySQL Joins
https://www.sitepoint.com/understanding-sql-joins-mysql-database/
http://dev.mysql.com/doc/refman/5.7/en/join.html
http://www.w3schools.com/sql/sql_join.asp
I think you can join on the sid, try this (but maybe just select whatever columns you want):
select l.*, u.*
from sys.sql_logins l
join sys.sysusers u on l.sid = u.sid
Postgresql Database
Table User
-----------
ID | Name
1 | John
2 | Bob
3 | Sarah
Table Photo
-------------
ID | Caption
1 | Vacation
2 | Birthday
3 | Christmas
Table Comment
--------------
ID | User ID | Photo ID| Text
1 | 1 | 1 | Mexico Looks Great
2 | 2 | 1 | Sure Does
3 | 3 | 1 | Too Hot
4 | 1 | 2 | Look at that cake
5 | 3 | 2 | No ice cream?
6 | 1 | 3 | So Happy
Desire: I want to get all the photos that ONLY John(1) and Sara(3) commented on.
How do I build a SQL query that looks for photos that only have comments from user #1 and user #3, I want to EXCLUDE results where more(or less) than those two commented on.
The clearest and most readable way, is the Photos containing comments by:
User1 Intersect User2 Except Any other user
This SQL Fiddle and query will return that:
SELECT *
FROM Photo
WHERE ID IN (
SELECT "Photo ID" FROM Comment WHERE "User ID" = 1
INTERSECT
SELECT "Photo ID" FROM Comment WHERE "User ID" = 3
EXCEPT
SELECT "Photo ID" FROM Comment WHERE "User ID" NOT IN (1, 3)
)
lets do three joins, one for john, one for sara, one for everyone else. Then we'll limit what we get back with the where clause.
select p.*
from photo p
left join comment john on john.photo_id=p.photo_id and john.user_id=1
left join comment sara on sara.photo_id=p.photo_id and sara.user_id=3
left join comment everyone_else on everyone_else.photo_id=p.photo_id and everyone_else.user_id<>3 and everyone_else.user_id<>1
where
everyone_else.id is null
and john.id is not null
and sara.id is not null
There are a couple of ways to do this. One is to use count with case:
select photoid
from comment
group by photoid
having count(distinct userid) = 2
and count(case when userid not in (1,3) then 1 end) = 0
SQL Fiddle Demo
Basically, make sure 2 users have commented and then make sure only user 1 or 3 commented.
You could use an intersection to find only the common photos, which would exclude photos commented by John but not Sarah, or vice versa
select photo_id from comment where user_id = 1
intersect
select photo_id from comment where user_id = 3
I have the following example table (simplified from what I really have as there are a few more joins in there)
|permission|username|
| perm1 | u1 |
| perm2 | u1 |
| perm3 | u1 |
| perm1 | u2 |
| perm4 | u2 |
I have many users and many groups in this table
I am having trouble with user permissions where some users can do things in my application and others cannot. At the moment I am having to manually go through and figure out what the differences are.
I want to crate a query from the above table that gives me an answer like this
|permission| u1 | u2 |
|perm1 | 1 | 1 |
|perm2 | 1 | 0 |
|perm3 | 1 | 0 |
|perm4 | 0 | 1 |
I do not really want 1 and 0 under the users but I want something to I can easily visualise that user 1 has these permissions and user2 does not. This would be really useful for me to ensure that users have the same permissions.
I have done the SQL to get the top table so I can see the permissions.
I was thinking that some sort of left join on itself might the answer there but everything I try seems to end up as invalid SQL.
Any hints please? Im happy to experiment if I get a starting point :)
Thanks in advance
What you're looking for is called "pivoting". One way to do that is a group by, like:
select permission
, count(case when username = 'u1' then 1 end) as User1
, count(case when username = 'u2' then 1 end) as User2
, count(case when username = 'u3' then 1 end) as User3
, ...
from YourTable
group by
permission
It looks like Oracle supports the PIVOT keyword. You can use it to accomplish the same thing:
select *
from YourTable
pivot (
count(*) as HasPermission
for (username) in ('u1', 'u2', 'u3', ...)
);
Example for both approaches at SQL Fiddle.
If i have two tables like
user table-"u"
userid | name
1 | lenova
2 | acer
3 | hp
pass table-"p"
userid | password
1 | len123
2 | acer123
3 | hp123
as for as i learnt from tutorials I can join these 2 tables using many joins available in
mysql as said here
If i have a table like
role table-"r"
roleid | rname
1 | admin
2 | user
3 | dataanalyst
token table-"t"
tokenid| tname
1 | xxxx
2 | yyyy
3 | zzzz
tole_token_association table-"a"
roleid | tokenid
1 | 1
1 | 2
3 | 1
3 | 3
3 | 1
I have to make a join such that I have to display a table which corresponds
like this "rolename" has all these tokens.How to make this? I am confused. Is it possible to make a join? I am liking mysql a lot. I wish to play with queries such that not playing. I want to get well versed. Any Suggestions Please?
It's easiest to see when the column names that need to be joined are named identically:
SELECT r.rname,
t.tname
FROM ROLE r
JOIN ROLE_TOKEN_ASSOCIATION rta ON rta.roleid = r.roleid
JOIN TOKEN t ON t.tokenid = rta.tokenid
This will return only the roles with tokens associated. If you have a role that doesn't have a token associated, you need to use an OUTER join, like this:
SELECT r.rname,
t.tname
FROM ROLE r
LEFT JOIN ROLE_TOKEN_ASSOCIATION rta ON rta.roleid = r.roleid
JOIN TOKEN t ON t.tokenid = rta.tokenid
This link might help -- it's a visual representation of JOINs.