I keep falling back into questions with MySQL joining.
And I would like to request a very simple example I could use to continue my journey of understanding learning the MySQL syntax.
Let's say I got the following table's
test_testtable
testtable_id
testtable_name
testtable_user
testtable_option
testtable_textfield
test_testlink
testlink_id
testlink_link
testlink_address
test_address
address_id
address_name
address_phone
address_email
address_street
address_city
address_zip
I would like to make a selection like :
SELECT * (lets say I would define the fields) FROM `test_testable`
JOIN `test_testtable`.`testtable_id` = `test_testlink`.`testlink_link`
AND
JOIN `test_testlink`.`testlink_addres` = `test_address`.`address_id`
WHERE `user_id` = 5
Hence the linking structure is like:
test_testtable.testtable_id = leading
table test_testlink is a table to link the table test_testtable and test_address
And linking table test_testlink uses the field testlink_link to link to the table test_testtable, and uses the field testlink_address to link to the table test_address
This does not work. FOR ME.. Since I continuously seem to fail of catching the correct syntax logic.
So I hope that someone could give me a small example of how to correctly implement such a simple yet critical query!
TIAD!!
A general approach :
SELECT table1.* FROM table1
JOIN table2 ON table2.id_table1 = table1.id
JOIN table3 ON table3.id_table2 = table2.id
WHERE table1.id = 10
For your purpose :
SELECT * (lets say I would define the fields) FROM `test_testable`
JOIN `test_testlink` ON `test_testtable`.`testtable_id` = `test_testlink`.`testlink_link`
JOIN `test_address` ON `test_testlink`.`testlink_addres` = `test_address`.`address_id`
WHERE `user_id` = 5
Please read the reference
You are using wrong syntax. You should mention which tables to join first then based on which fields.
SELECT * (lets say I would define the fields) FROM `test_testable`
INNER JOIN test_testlink
ON `test_testtable`.`testtable_id` = `test_testlink`.`testlink_link`
INNER JOIN `test_address`
ON `test_testlink`.`testlink_addres` = `test_address`.`address_id`
AND `test_testtable`.`user_id` = 5
select * from testlink JOIN testtable ON testlink.tableid = testtable.ID
JOIN testaddress ON testlink.addressid = testaddress.ID
WHERE testtable.ID = 5
Related
I am trying to make a "recipe" system inside a game. The player can own a company and craft items in there.
I currently fetch the recipes per company type but I don't know how to write the query in a way that I can also fetch the item names and images if the item_id is not empty.
This is working:
SELECT a.recipe_id,
a.item1_id,
a.item1_uses,
a.item2_id,
a.item2_uses,
a.item3_id,
a.item3_uses,
a.item4_id,
a.item4_uses,
a.item5_id,
a.item5_uses,
a.newitem_id,
a.newitem_uses,
a.craft_description,
a.craft_button
FROM
company_recipes AS a,
company_types AS b
WHERE
a.type_id = b.type_id
AND
b.type_id = '".$type."';
"
A recipe can contain for example two items needed to craft something new, but it could also be 5. So if it's only 2, I only want to fetch the img, name of these 2 and the rest can be skipped.
I have a different table store_items that contains the img and name of the item. I was thinking something along the lines of an IF ELSE or CASE WHEN inside the query, but I'm not sure how I'd do that.
Something like: SELECT c.img, c.name FROM store_items AS c IF a.item1_id is not NULL.
I feel like I'm close to the solution, but missing the last step.
Thanks for the tips #jarlh, I've changed the code and came to this result. If you have any more tips to do it better I'm happy to listen. (I'm still a junior and thought myself by trial and error, so I might not have the best solutions at times... Which is why tips are highly appreciated).
SELECT cr.recipe_id,
cr.item1_id,
cr.item1_uses,
si1.name,
si1.img,
cr.item2_id,
cr.item2_uses,
si2.name,
si2.img,
cr.item3_id,
cr.item3_uses,
si3.name,
si3.img,
cr.item4_id,
cr.item4_uses,
si4.name,
si4.img,
cr.item5_id,
cr.item5_uses,
si5.name,
si5.img,
cr.newitem_id,
cr.newitem_uses,
si_new.name,
si_new.img,
cr.craft_description,
cr.craft_button
FROM
company_recipes AS cr
INNER JOIN company_types AS ct ON cr.type_id = ct.type_id
LEFT JOIN store_items AS si1 ON cr.item1_id = si1.item_id
LEFT JOIN store_items AS si2 ON cr.item2_id = si2.item_id
LEFT JOIN store_items AS si3 ON cr.item3_id = si3.item_id
LEFT JOIN store_items AS si4 ON cr.item4_id = si4.item_id
LEFT JOIN store_items AS si5 ON cr.item5_id = si5.item_id
LEFT JOIN store_items AS si_new ON cr.newitem_id = si_new.item_id
WHERE
ct.type_id = '".$type."';
I'm basically fetching everything now and handle the NULLs in the php code now.
Without seeing more info its had to see what you are trying achieve but you could start by using the the users inpute of the game to determine what data is first required before futher filtering. Try this:
Declare #Value int
set #Value = #User_input --- uses what ever the game user will
SELECT
a.recipe_id,
a.item1_id,
a.item1_uses,
a.item2_id,
a.item2_uses,
a.item3_id,
a.item3_uses,
a.item4_id,
a.item4_uses,
a.item5_id,
a.item5_uses,
a.newitem_id,
a.newitem_uses,
a.craft_description,
a.craft_button
--- you can insert more columns but i stopped here as i dont know what data you have in the other tables.
FROM
company_recipes a
INNER JOIN company_types b ON a.type_id = b.type_id
INNER JOIN store_items c ON c.type_id = b.type_id
WHERE
b.type_id = #Value; --- '".$type."';
please advise on query below. I want to select multiple tables. entryId is from table stockTracking. I bet i should use JOIN or smt.. Cheers!
$updateEntryId = $_GET["entryId"];
$query = "SELECT *
FROM stockTracking, loggers, boxes
WHERE entryId ='$updateEntryId'";
$result = mysqli_query($connection, $query);
table
boxes|boxId boxQuantity boxName
2 10 CL64
loggers | loggerId loggerQuantity loggerName
2 10 34242342
stockTracking| entryId time destination reference
2 timestamp Paris 1312
I have updated query to following, however what wrong with my WHERE statement?
As i add WHERE entryId='$updateEntryId' if fails to display any results
$updateEntryId = $_GET["entryId"];
$query = "SELECT *
FROM stockTracking
JOIN loggers
ON entryId=loggerId
JOIN boxes
ON boxId=entryId
WHERE entryId='$updateEntryId'";
Yes, you are right. You should perform a JOIN operation among-st the tables like below. replace some_column in below sample sql code with your actual column name on which you have relationship between the tables
SELECT s.*
FROM stockTracking s
JOIN loggers l ON s.some_column = l.some_column
JOIN boxes b ON b.some_column = s.some_column
WHERE s.entryId ='$updateEntryId'
Try this out:
$updateEntryId = $_GET["entryId"];
$query = "SELECT *
FROM stockTracking s
JOIN loggers l
ON s.entryId=l.loggerId
JOIN boxes b
ON b.boxId=s.entryId
WHERE s.entryId='".$updateEntryId."'";
Join the tables as stated by #rahul but should be done in proper manner .. cheers!
SOLVED.
Problem was in $updateEntryId=$_GET["entryId"];
It had no results, since as search bar was showing http://stock/edit.php?id=2, it was looking for $_GET["id"] and not $_GET["entryId"].
I have 2 tables.
Table A: trades: which contains the columns: tradeID, tradeName, tradeShow, and tradeGuy.
Table B: offers: which contains the columns: tradeID, offerName, offerGuy.
I'm trying to select all columns from table A (trades) WHERE the value of "tradeShow" = 'Yes', And the value of "tradeGuy" != the user's Username. That much is easy, but I also don't want to select any records which have an offer created by the user. In other words, in table B (offers), offerGuy != Username WHERE trade ID from Table B = tradeID from Table A.
But, how do I merge these 2 conditions? I've tried this:
$sql = "SELECT *
FROM trades t1
JOIN offers t2
ON (t1.tradeID = t2.tradeID)
WHERE t1.tradeShow='Yes' AND t1.tradeGuy!='$username' AND t2.offeringGuy!='$username'";
But the problem with that is it only selects the records from trades which have an offer, because of the forth line: ON (t1.tradeID = t2.tradeID), as in it only selects trades which have a record in (offers) that mentions their tradeID.
I've also tried an awkward attempt to link the 2 tables with a meaningless link by adding a "linker" column to each table with the default value of "XXX", and did this:
$sql = "SELECT *
FROM trades t1
JOIN offers t2
ON (t1.linkerA = t2.linkerB)
WHERE t1.tradeShow='Yes' AND t1.tradeGuy!='$username' AND (t2.offeringGuy!='$username' WHERE t1.tradeID=t2.tradeID)";
But the problem with that is using 2 Where clauses...
So, how do I merge the 2 conditions?
What you're looking for is called an OUTER JOIN (in this case a LEFT OUTER JOIN) which will give you null results for missing matches, something like;
SELECT *
FROM trades t1
LEFT OUTER JOIN offers t2
ON t1.tradeID = t2.tradeID AND t2.offeringGuy = '$username'
WHERE t1.tradeShow='Yes' AND t1.tradeGuy!='$username' AND t2.offeringGuy IS NULL
We add a condition to the LEFT JOIN that we're only interested in matches against t2.offeringGuy = '$username', which will return NULL values in t2's fields if there is no match.
Then we just check that t2.offeringGuy IS NULL to find the non matches.
I would do this with not exists rather than an explicit join:
SELECT *
FROM trades t
WHERE t.tradeShow = 'Yes' AND t.tradeGuy <> '$username' and
not exists (select 1
from offers o
where t.tradeID = o.tradeID and o.tradeGuy = '$username'
);
I have three tables.
I combine the company and component tables with this code
$questions_query = "SELECT company_mast.id, component_mast.component_id
FROM company_mast
LEFT JOIN component_mast
ON company_mast.id = component_mast.company_id
WHERE component_mast.component_name = '".$component_name."'
AND company_mast.company_name = '".$company_name."'";
The result is as desired, If I put company_name as Bells and component_name as Assets I get and id of 3 for Bells and an id of 9 for Assets. Now if you look at the customfields table I need to pull all the questions with the a specific company_id and component_id.
Example: If the user enters Bells and Assets they need to receive all questions with the company_id of 3 and the component_id of 9.
So this is my query
SELECT *
FROM customfield_mast
LEFT JOIN ( SELECT company_mast.id, component_mast.component_id
FROM company_mast
LEFT JOIN component_mast
ON company_mast.id = component_mast.company_id
WHERE component_mast.component_name = 'Assets'
AND company_mast.company_name = 'Bells')
att
ON customfield_mast.company_id = customfield_mast.component_id
This however returns all questions in my db, which is not what I want. I'm positive my last "ON" statement is the problem, however I don't know what the correct statement would be. I have not started with SQL injection protection, this is grass roots to get my queries to work. Thanks for the help
What's wrong with another join?
SELECT company_mast.id, component_mast.component_id, CFM.DisplayName
FROM company_mast
LEFT JOIN component_mast
ON company_mast.id = component_mast.company_id
LEFT JOIN CustomField_mast CFM
ON CFM.Company_ID = Component_mast.Company_ID
and CFM.Component_ID = component_Mast.Component_ID
WHERE component_mast.component_name = '".$component_name."'
AND company_mast.company_name = '".$company_name."'";
SELECT * FROM `customfield_mast`
WHERE `company_id` =
(SELECT `id` FROM `company_mast` WHERE `company_name` = '$company_name')
AND `component_id` IN
(SELECT GROUP_CONCAT(`component_id`) FROM `component_mast`
WHERE `component_name` = '$component_name')
I have two tables and joined them to one different table
1 table named 'rec_dept'
id_dept
id_divisi
nama_dept
2 table named 'rec_divisi'
id_divisi
nama_div
3 joined table named 'rec_divdep'
id_divdep
id_divisi
id_dept
How to get nama_dept where in the same id_divisi?
Maybe you're looking for this:
SELECT `nama_dept` FROM `rec_dept` WHERE `id_divisi` IN (SELECT `id_divisi` FROM `rec_divdep`);
Hope that helps
you can do a SELECT query with a LEFT JOIN function to get data
SELECT a.`nama_dept` FROM `rec_dept` a
LEFT JOIN `rec_divisi` b
ON a.`id_divisi` = b.`id_divisi`
ORDER BY a.`id_divisi` ASC
SELECT documentation
LEFT JOIN documentation
select a.id_dept, a.id_divisi, a.nama_dept, b.id_divisi, b.nama_div, c.id_divdep, c.id_divisi from rec_divdep as c left join rec_divisi as b on (c.id_divisi = b.id_divisi) left join rec_dept as a on (c.id_divisi = a.id_divisi)
what database do you use. I code mine as mysql, basically I condition the three tables that has same id_divisi. I did not test it but I am pretty sure of the logic based on what I understand.