Ok, I have this first table which has, among other things:
table 1: id | depID (every id has one depID)
Then, I have a second table where I have table 2: userID | depID (where an userID is associated with multiple depIDs in separate rows. Also, I have table 3 with userID | rankID (where an userID is associated with one rankID).
I need to get all id and depID from table 1, and then to check, which userIDs of table 2 shares the same depID (table1.depID = table2.depID), and then, to check which of those userIDs from table 2 has rankID = $rID
Thanks guys.
I think this SQL should get you what you want, but I'm not 100% clear from the wording of the question:
SELECT table2.userID
FROM table1
JOIN table2
ON table1.depID = table2.depID
JOIN table3
ON table2.userID = table3.userID
AND table3.rankID = $rID;
Related
I have two tables.
first datatable structure has nine columns but the important three are:
code | name | value
2D3 | name test | 0.12
the second table has the same three columns.
Now I want to update all rows of the first table with the values of table two where code AND name are the same as in table two.
So my current idea is to do a select of all rows of table 1 with the code and name columns, than check if a row with the same code and name exists in table 2, if yes get that value and do a UPDATE query in table 1 with value of table 2.
The problem is that the two tables are hugh and I am sure that I am not using the fastest method.
anyone an idea for the fastest method to do this? Thank you very much!
EDIT: the query:
$getall = "SELECT code, name, value FROM table2";
$query = mysqli_query($conn, $getall );
while($result = mysqli_fetch_array($query))
{
$UpdateAll = "UPDATE table1 SET value = '".mysqli_real_escape_string($conn,$result["value"])."' WHERE name = '".mysqli_real_escape_string($conn,$result["name"])."' AND code = '".mysqli_real_escape_string($conn,$result["code"])."'";
$result2 = mysqli_query($conn, $UpdateAll); }
You speak of two databases but really mean two tables, don't you? In this case, you can do it with one update using a join, like this:
update table1 t1
inner join table2 t2 on t2.code = t1.code and t2.name = t1.name
set t1.value = t2.value;
I am trying to SELECT rows from a table where it has got a foreign key on second table and the key from the second table is used in a third table as foreign key. How can I retrieve the rows from the first table where on the third table doesn't have the key from the second table which this particular key's row has got the first tables' row's primary key as foreign key and also on the third table it hasn't got the foreign key of the fourth table.
I tried using inner join but it only works with SELECTING rows where it has got a specify value rather than not having this specify value.
Please help me
Faculty table
FaculID | FaculName | FaculLocation |
Course table
CourseID | CourseName | CourseDescription
FacultyCourse table
fcID | CourseID | FaculID
Registeration table
RegID | fcID | stuID
Student table
stuID | stuName | stuAge | stuAddress
so basically what i want to do now is get all bid where the e table hasn't got uid and did(which has got a bid foreign key).
Try to use LEFT OUTER JOIN:
SELECT a.*
FROM a
LEFT OUTER JOIN b on a.keya = b.keybjoina
LEFT OUTER JOIN c on b.keybjoina = c.keycjoinb
WHERE c.keycjoinb IS NULL
Try:
(change table and column names as appropriate)
updated based on example layout
select *
from faculty
where faculid not in (select faculty.FaculID
from faculty
join facultycourse
on faculty.FaculID = FacultyCourse.FaculID
join registration
on registration.fcid = FacultyCourse.fcid
where registration.stuid = 'XYZ');
EDIT by:lawrence.
I got the right query now
select *
from users, friends
where (users.id=friends.user_id1 and friends.user_id2=$profileID) or (users.id=friends.user_id2 and friends.user_id1=$profileID)
Question answered
I need some help joining results from my friends and users table
This is what my friends table look like
id user_id1 user_id2
1 | 2 | 3
1 | 2 | 4
1 | 2 | 5
1 | 6 | 2
Users table
id name
2 | sarah
3 | emma
4 | lawrence
5 | cynthia
6 | suzie
I could easily just have two rows for each relation and do a simple query.
But i prefer having one row per relation,
So lets assume that we are watching page member.php?profile=2
and there is a list of friends, what does the query look like.
This works fine if i have two rows per relation but i dont want that....
SELECT * FROM friends, users WHERE friends.user_id1 = $profileID AND friends.user_id2 = users.id ORDER BY friends.id DESC LIMIT 16
Do you get me? something along like
SELECT * FROM friends,users WHERE friends.user_id1 = $profileID AND ALSO WHERE friends.user_id2 = $profileID AND THEN GET FROM users WHERE users.id = friends.user_id1 AND ALSO WHERE users.id = friends.user_id2
I hope I made myself clear
I'm not sure i understand your question but won't this do?
SELECT * FROM friends, users where friends.user_id1 = $profileID or friends.userid2 = $profileID and users.id = friends.user_id1 or users.id = friends.user_id2
You want a left join (using the LEFT JOIN operator), not a cartesian join (using the FROM table1, table2 syntax).
http://www.w3schools.com/sql/sql_join_left.asp
Tip: With your cross-reference table instead of having an id column you can create a compound key.
I have 4 tables in a mysql database that i need to add/edit/manage.
The difficulty, is that each one, is dependent on the one before it.
The way i have this setup on the user end, is you select an option from table 1.
You are then presented with the options in table 2, that have the first option's ID in their row.
Once you select option in table 2, you are taken to table 3, which generates its list where the rows contain the ID of your selection in table 2, and so on and so forth.
The problem is how to edit/manage this.
Obviously if you delete an option in table 1, all its subsequent child options will be invalid.
I just need an idea of how to manage a setup like this.
Without many details it's hard to comment on your exact situation, but here's a way to organize your MySQL database structure:
TABLE table1
INT id
... other data ...
TABLE table2
INT id
INT table1_id FOREIGN_KEY table1
... other data ...
TABLE table3
INT id
INT table2_id FOREIGN_KEY table2
... other data ...
TABLE table4
INT id
INT table3_id FOREIGN_KEY table3
... other data ...
And your url structure for your site could be:
/table1/add
/table2/add?table1_id=T1_ID
/table3/add?table2_id=T2_ID
/table4/add?table3_id=T3_ID
/table1/(edit,delete)/T1_ID
/table2/(edit,delete)/T2_ID
/table3/(edit,delete)/T3_ID
/table4/(edit,delete)/T4_ID
For adding to table2,3,4:
INSERT INTO table2 (data, table1_id) VALUES(data, T1_ID);
For deleting from table1:
DELETE FROM table1 WHERE id = T1_ID;
$t2_ids = SELECT id FROM table2 WHERE table1_id = T1_ID;
DELETE FROM table2 WHERE table1_id = T1_ID;
$t3_ids = SELECT id FROM table3 WHERE table2_id IN ($t2_ids);
DELETE FROM table3 WHERE table2_id = $t2_ids;
$t4_ids = SELECT id FROM table4 WHERE table3_id IN ($t3_ids);
DELETE FROM table4 WHERE table3_id = $t3_ids;
And so and so forth if you're deleting from the sub tables.
Additionally, if your data in each table isn't very different, you can use a single table to maintain the parent/child relationships
TABLE table
INT id
INT parent_id
... other data ...
Your URL structure won't change much, but your deleting pseudo-code can be optimized to use subselects on the table itself.
Multi-tiered data is most-often stored in with a parent:child relation field in a table.
id | name | parent_id
----------------------
1 | Mom | NULL
2 | Son | 1
Write a recursive function/query to traverse the relationships and any updates/inserts/deletes should be relatively simple.
I'm trying to join two tables. The first table has a list of 11 items which are 'site_names' with an auto id field of 'id'. The second table that I want to connect has an auto id field of 'desc_id' and another field of 'descriptions'. This second table currently has 3 rows of data that I want displayed only for id 1 in table 1.
So, I want to accomplish is to connect the first site in table one with an id of '1' to the entire second table.
I can't seem to figure out how connect only the first entry(id=1) in table 1 to all the rows in table 2 (tb.1->id->1 to tbl.2->desc_id->1,2,3).
I hope that made sense. Any help would be great. Thanks
Try:
select site_name, descriptions
from table_1
inner join table_2
on 1 = 1
where table_1.site_id = 1
This should join give you what you want.
OK - based on the comment, I'm guessing what you want is:
site1 | desc1 | desc2 | desc3
all on one row. This is a bit trickier - particularly if you want it to remain open to an arbitrary number of descriptions. For just 3 (or, really, any limited subset, but as the number goes up, it gets ugly), you could do:
select site_name, t2.desc, t3.desc, t4.desc
from table_1
inner join table_2 t2
on t2.desc_id = 1
inner join table_2 t3
on t3.desc_id = 2
inner join table_2 t4
on t4.desc_id = 3
where site_id = 1
This kind of stuff is highly irregular though. It seems to me like something about your schema is probably not quite right to generate this sort of requirement.
Here is the query:
<?php
$mysql = new mysqli('localhost', 'root', 'root') or die('counld not connect');
$result = $mysql->query("SELECT ajax_demo.explore.site_name, anthony1.property.descriptions FROM ajax_demo.explore INNER JOIN anthony1.property ON ajax_demo.explore.id = anthony1.property.desc_id") or die($mysql->error);
if($result)
{
while($row = $result->fetch_object())
{
$id = $row->id;
$siteName = $row->site_name;
$siteDescription = $row->site_description;
echo "$siteName";
echo "$siteDescription";
}
}
?>
I may be missing something here, but it sounds to me like you need to add a foreign key to the Site table. If I understand your question correctly, your tables should look something like this:
Site
- SiteID
- DescriptionID
- SiteName
Description
- DescriptionID
- Description
Then your query to get Sites and their associated Descriptions would look like this:
SELECT
s.SiteName,
d.Description
FROM
Site s INNER JOIN Description d
ON s.DescriptionID = d.DescriptionID
This table structure assumes that multiple Sites share single Descriptions (as per your posted question).