I want to create mysql request to the server I want to retrieve users from the table that as I do not have in friends list.
Here's how I'm trying to learn but I do not receive please help me
SELECT
t1.*, t2.*
FROM
users as t1,
friends as t2
WHERE
t2.user_id='1'
and t2.fr_id!=t1.id
ORDER BY RAND()
The query you want is something like:
SELECT t1.*, t2.*
FROM users t1 left outer join
friends t2
on t2.fr_id = t1.id and
t2.user_id = '1'
WHERE t2.user_id is null
ORDER BY RAND();
I'm not sure what the t2.user_id = 1 is doing. It is not needed if you are looking through the entire friends list.
Related
Good evening,
I have two tables t1 and t2
In t1, I have two variables, ID (which uniquely identify each row) and DOC (which can be common to several IDs)
In t2, I have three variables, ID (which does not necessarily uniquely identify the rows here), AUTH , and TYPE. Each ID has a maximum of 1 distinct AUTH.
Sample data:
What I would like to do is to select the DOCs that have an ID with AUTH='EP', and that also have an ID with AUTH='US'. They could have additional IDs with other AUTH, but they have to have at least these two.
Thus, i would have a final table with the DOC, ID,and AUTH (there should be at least 2 IDs per doc, but it can be more if there exists an additional AUTH to US and EP for this DOC)
The desired results:
This should work:
SELECT DISTINCT (T1.ID), T1.DOC, T2.AUTH FROM T1
LEFT JOIN T2 ON T2.ID = T1.ID
WHERE T1.DOC IN( SELECT T1.DOC FROM T2
LEFT JOIN T1 ON T1.ID = T2.ID
WHERE T2.AUTH IN('EP','US')
GROUP BY T1.DOC HAVING COUNT(DISTINCT T2.AUTH) = 2) ;
If I could understand correctly the query is going to be something like that:
select t1.doc, t1.id, t2.auth from t1
left join t2 on t2.id = t1.id
where t1.doc in( select t1.doc from t2
left join t1 on t1.id = t2.id
where t2.auth in('EP','US') );
Although, the result set is basically going to be the first sample data table, due to the ID 6 which has a AUTH = "EP" and, consequently, the ID 7 which has the same DOC from ID 6.
I have 3 tables and want to join all in one query to show latest 10 entries by datetime.
t1: id, username
t2: id, id_t1, med_id, ga_id, au_id, re_id, text, datetime
t3: id, id_t1, pro_id, au_id, re_id, text, datetime
First I saw it would be easy with simple left join and where id, but i got double results. Then i tried inner and outer join, also group by, but the result was bad.
So my question is how can i join all without double results of the last 10 of t2 and t3?
Hard to tell what exactly you are trying to acheive, but here is a clue how it could be complemented.
SELECT TOP 10 DISTINCT T1.*
FROM T1
INNER JOIN T2 ON T1.id = T2.id_t1
INNER JOIN T3 ON T1.id = T3.id_t1
ORDER BY (CASE WHEN T2.[DateTime] > T3.[DateTime] THEN
T2.[DateTime]
ELSE
T3.[DateTime]
END) DESC
If you need to select field from T2 and T3, GROUP BY on all T1 field with aggregate on field from t2 and t3 is an option. Otherwise, linked-subquery is the way to go.
As sgeddes commented already, it's hard to know what you need, without seeing some example data from your tables. It would really help to know what the relationship between the three tables is.
One question I have, in particular, is: how are t2 and t3 related, if at all? It looks like they might not be, as each of them has its own datetime column.
Perhaps the following could do the job, but we need some more info to know for sure:
(SELECT DISTINCT t1.*, t2.id, t2.au_id, t2.re_id, t2.text, t2.`datetime`, t2.med_id, t2.ga_id, NULL AS pro_id
FROM t1
INNER JOIN t2 ON t1.id = t2.id_t1)
UNION
(SELECT DISTINCT t1.*, t3.id, t3.au_id, t3.re_id, t3.text, t3.`datetime`, NULL AS med_id, NULL AS ga_id, t3.pro_id
FROM t1
INNER JOIN t3 ON t1.id = t3.id_t1)
ORDER BY datetime DESC
LIMIT 10
The following selects the username and the datetime for the last ten posts.
SELECT username, last_ten.`datetime` AS lastpost
FROM t1
INNER JOIN (
SELECT 't2' AS tab, id, `datetime`, t2.id_t1
FROM t2
UNION ALL
SELECT 't3' AS tab, id, `datetime`, t3.id_t1
FROM t3
ORDER BY datetime DESC
LIMIT 10
) AS last_ten ON t1.id = last_ten.id_t1
I have two tables from which I need to get data in the same SELECT output. The thing is that I need to limit the amount of results.
Say I have an ID column that is unique in table1, but in table2 it has many rows with that ID.
Now I just want to list how many different IDs I have in table1 and some other information stored in table2.
How can I get the desired output I show in the end?
To make my idea clear I used a "messenger" database for an example.
Tables
T1
Id_thread Date
1 13Dic
2 12Dic
T2
Id_thread Message Name
1 Hi Someone
1 Hi to you Someone
2 Help me? Someother
2 Yes! Someother
Desired output
T1.Id_thread T2.Name T1.Date
1 Someone 13Dic
2 Someother 12Dic
I'd join and use distinct:
SELECT DISTINCT t1.id_thread, t2.name, t1.date
FROM t1
JOIN t2 ON t1.id_thred = t2.id_thread
Use a JOIN and GROUP BY:
SELECT t1.Id_thread, t2.Name, t1.Date
FROM t1
JOIN t2 ON t1.Id_thread = t2.Id_thread
GROUP BY t1.Id_thread
Note that if Name is the same for all rows in t2 that have the same Id_thread, that column probably should be in t1. If you fix that, you don't need the JOIN.
Try this:
SELECT DISTINCT T1.Id_thread, T2.Name, T1.Date
FROM T1
LEFT OUTER JOIN T2 ON T1.Id_thread = T2.Id_thread
select T1.Id_thread,T2.Name,T1.Date from T1
inner join T2 on T1.Id_thread = T2.Id_thread
group by T1.Id_thread
order by T1.Id_thread
You haven't specified how you want the limit the results from Table 2. Considering you just want one row, you can use a CROSS APPLY:
Select T1.Id_thread,T2Table.Name,T1.Date From T1
Cross Apply (Select Top 1 T2.Name From T2 Where T2.Id_thread=T1.Id_thread) T2Table
You can specify other conditions in the inner Select statement if you wish.
I have a query now which works great for finding player info including their rank:
SELECT t1.pid,
t1.type,
t1.pspeed,
t1.distance,
t1.maxspeed,
t1.prestrafe,
t1.strafes,
t1.sync,
t1.wpn,
1+SUM(t2.pid IS NOT NULL) as rank
FROM records t1
LEFT JOIN records t2
ON t1.type = t2.type
AND t1.pspeed = t2.pspeed
AND t1.distance < t2.distance
WHERE t1.pid = "'.$pid.'"
AND t1.type IN ("type1","type2","type3")
GROUP BY t1.type, t1.pspeed
The problem now is that I wish to use an authid instead of a pid as my variable. I can do an easy join on the records table along with a player table that has an id equal to the pid in the records table as well as the authid I wish to search by:
SELECT * FROM records JOIN players ON records.pid=players.id
I wish to use this second query in place of the FROM records portion of the first query but I've confused myself in my attempts via the many aliases used.
Here's a pitiful example of an attempt:
SELECT t1.pid,
t1.type,
t1.pspeed,
t1.distance,
t1.maxspeed,
t1.prestrafe,
t1.strafes,
t1.sync,
t1.wpn,
1+SUM(t2.pid IS NOT NULL) as rank
FROM (
SELECT *
FROM records
JOIN players ON records.pid=players.id
) t3 t1
LEFT JOIN records t2
ON t1.type = t2.type
AND t1.pspeed = t2.pspeed
AND t1.distance < t2.distance
WHERE t1.authid = "'.$authid.'"
AND t1.type IN ("type1","type2","type3")
GROUP BY t1.type, t1.pspeed
Anyone able to whip me into shape please feel free to do so. I'm awful at SQL still.
Your Join looks pretty close. However you gave your subquery two aliases. Try just one
SELECT t1.pid, t1.type, t1.pspeed, t1.distance, t1.maxspeed, t1.prestrafe, t1.strafes, t1.sync, t1.wpn, 1+SUM(t2.pid IS NOT NULL) as rank
FROM
(
SELECT players.*, rec.pid, rec.type, rec.pspeed, rec.distance, rec.maxspeed,
rec.prestrafe, rec.strafes, rec.sync, rec.wpn
FROM records AS rec JOIN players ON rec.pid = players.id ) AS t1
LEFT OUTER JOIN records t2
ON t1.type = t2.type AND t1.pspeed = t2.pspeed AND t1.distance < t2.distance
WHERE t1.authid = "'.$authid.'" AND
t1.type IN ("type1","type2","type3")
GROUP BY t1.type, t1.pspeed
Also, naming your columns in your subquery should eliminate the duplicate column error.
Table 1 has columns : entry_id user_id ...
Table 2 has columns : entry_id user_id ...
the user_id entry is not always the same so I would like to extract both of them so I can later on compare them in my script
SELECT * FROM
table1 as t1
INNER JOIN table2 as t2 on t1.entry_id=t2.entry_id
WHERE t1.user_id='%s'
I would like to extract t1.user_id and t2.user_id ...the problem is the result array has only user_id
thank you
Use AS keyword:
SELECT
t1.user_id as t1_user_id
,t2.user_id as t2_user_id
FROM table1 as t1
INNER JOIN table2 as t2
ON t1.entry_id=t2.entry_id
WHERE t1.user_id='%s'
SELECT t1.user_id AS user_id_1, t2.user_id AS user_id2, ...
I think the framework executing the query is at fault for "merging" the two columns here, the result set should have both, but these are stored into an associative array somewhere along the line.
It is a good idea to only request those columns you actually need nonetheless :)
You can effectively use ALIASING (i.e. use the AS keyword).
SELECT t1.user_id as user_id_1, t2.user_id as user_id_2 FROM
table1 as t1
INNER JOIN table2 as t2 on t1.entry_id=t2.entry_id
WHERE t1.user_id='%s'