I have 3 tables to select from. 2 of them are always necessary (tbl_notes, tbl_clients) while the 3rd is optional (tbl_notes_categories).
I've always used a LEFT JOIN in my queries with questionable correlating records to the primary table.
But I'm not getting any results with the query below.
Would someone point out how I'm using the LEFT JOIN incorrectly?
SELECT n.*, c.clientname, nc.notecategoryname
FROM tbl_notes n, tbl_clients c
LEFT JOIN tbl_notes_categories nc ON n.categoryid = nc.categoryid
WHERE n.clientid = c.clientid
AND c.clientid = 12345
ORDER BY n.dateinserted DESC
In fact, I'm getting a sql error.
#1054 - Unknown column 'n.categoryid' in 'on clause'
categoryid certainly does exist in tbl_notes
I probably need to brush up on how JOINS really work. I'm guessing I cannot have a LEFT JOIN with 2 database tables before it?
On a side note, I can foresee times when there will be multiple required tables, with several optional tables. (in this case tbl_notes_categories is optional)
Assuming the column categoryid exists in the tbl_notes table...
Try rewriting the query to use the JOIN syntax, rather than using the old-school comma as the join operator. (If the problem isn't a misnamed column, I suspect the problem is in mixing the two types of syntax... but this is just a suspicion, I have no reason to test mixing old-style comma joins with JOIN keywords.)
I'd write the statement like this:
SELECT n.*, c.clientname, nc.notecategoryname
FROM tbl_notes n
JOIN tbl_clients c
ON n.clientid = c.clientid
LEFT
JOIN tbl_notes_categories nc
ON nc.categoryid = n.categoryid
WHERE c.clientid = 12345
ORDER BY n.dateinserted DESC
(Actually, I would specify the individual columns to return from n, rather than using n.*, but that's just a style preference, not a SQL syntax requirement.)
Related
Im supposed to be converting this query from MYSQL to SQL Server. However, the join statement is throwing me off. I haven't seen joins done like this and I am slightly confused on how to translate it.
SELECT
`Supplier Confirmed Orders` + `Log Tech Confirmed Orders` AS 'orders confirmed',
`Orders in CVN`-`Cancelled Orders` AS 'Orders in CVN',
tblloadingmonths.`month`,
tblvendorindex.`vendorindexid`,
'Service' AS category
FROM
tblloadingmonths
JOIN
tblvendorindex
LEFT JOIN
tblcvn ON tblloadingmonths.`month` = tblcvn.`month`
AND tblvendorindex.vendorindexid = tblcvn.vendorindexid
Whats throwing me off is that the loadingmonths and vendorindex tables dont have any common fields, but theyre being joined, and then left joined with cvn. I've always been taught to do tableA join tableB ON colA = colB join tableC ON colB = colC, but not tableA join talbeB left join tableC ON colA = colC AND colB = colC. As it stands, the query cant run in SQL Server with the joins the way the way they are. I had to set it up like this:
SELECT
CVN.[Supplier Confirmed Orders] + CVN.[Log Tech Confirmed Orders] AS 'orders confirmed',
(CVN.[Orders in CVN] - CVN.[Cancelled Orders]) AS 'Orders in CVN',
tblloadingmonths.month,
tblvendorindex.vendorindexid,
'Service' AS category,
'CVN Compliance' as metric
FROM
cvn
JOIN
tblvendorindex ON tblvendorindex.vendorindexid = CVN.vendorindexid
INNER JOIN
tblloadingmonths ON tblloadingmonths.month = CVN.month
Im getting different results for this converted query. Any guidance would be greatly appreciated
You are taught correctly in that you should list your join clause (ON...) and the second query is obviously far more readable and is preferred. Similarly, old-style joins simply list everything in the WHERE clause for INNER JOIN but again, this is hard to read. Regarding your different results. They are different because
cvn table name is different from tblcvn meaning it's a different object. If that was a type-o then...
In the first you LEFT JOINing to the tblloadingmonths and tblloadingmonths tables... meaning the rows must exist in both of those (for your join clause) for tblcvn rows to be returned. However, since it's a LEFT JOIN, the rows for tblloadingmonths and tblloadingmonths will be returned regardless of the match in tblcvn. In the second, you are using cvn as the base table and using INNER JOIN throughout. This means that the match must exists for the join clause for the rows in cvn to be returned. Otherwise, they would be filtered.
To recap, when using LEFT JOIN...
The table in the FROM clause matters. Swapping it with a LEFT JOIN table could change the results (as you witnessed)
Criteria in a WHERE clause could turn the LEFT into an INNER join.
I can't tell you if MySQL automatically assigns a join based on key assignments, or if it's making a Cartesian product. When using JOIN in SQL Server you have to list the ON clause. You could use old style joins... FROM Table1, Table2... but this should get you as Cartesian without a WHERE clause. This should get you close with some edits on your part:
SELECT
CVN.[Supplier Confirmed Orders] + CVN.[Log Tech Confirmed Orders] AS 'orders confirmed',
(CVN.[Orders in CVN] - CVN.[Cancelled Orders]) AS 'Orders in CVN',
tblloadingmonths.month,
tblvendorindex.vendorindexid,
'Service' AS category,
'CVN Compliance' as metric
FROM
tblvendorindex
INNER JOIN
tblloadingmonths ON tblvendorindex.??? = tblloadingmonths.???? --find out what the relation is, a foreign key perpahs. Would need a data model to determine.
LEFT JOIN
cvn ON tblloadingmonths.month = cnv.month
AND tblvendorindex.vendorindexid = cvn.vendorindexid
Thanks to your comments, you confirmed the MySQL join was producing a Cartesian Product implicitly which you can achieve with a CROSS JOIN explicitly in SQL Server, as you answered.
SELECT
CVN.[Supplier Confirmed Orders] + CVN.[Log Tech Confirmed Orders] AS 'orders confirmed',
(CVN.[Orders in CVN] - CVN.[Cancelled Orders]) AS 'Orders in CVN',
tblloadingmonths.month,
tblvendorindex.vendorindexid,
'Service' AS category,
'CVN Compliance' as metric
FROM
tblvendorindex
CROSS JOIN tblloadingmonths
LEFT JOIN
cvn ON tblloadingmonths.month = cnv.month
AND tblvendorindex.vendorindexid = cvn.vendorindexid
I am trying to append 'lookup data' to a main record text/description field so it looks something like this:
This is the Description Text
LookUpName1:
LookupValue1
LookupValueN
This worked fine with Inner Join like so
Select J.id, Concat('<b>LookUpName</b>:<br>',group_concat(F.LookUpValue SEPARATOR '<br>'))
from MainTable J Inner Join
LookUpTable L Inner Join
LookUpValuesTable F
On J.ID = L.JobID and F.ID = L.FilterID
Group by J.ID
However my goal is to add append multiple Lookup Tables and if I add them to this as Inner Joins I naturally just get those record where both/all the LookupTables have records.
On the other hand when I tried Join or Left Join I got an error on the Group by J.ID.
My goal is to append any of the existing Lookup Table values to all of the Description. Right now all I can achieve is returning appended descriptions which have ALL of the Lookup table values.
Your query would work if the on clauses were in the "right" place:
select J.id,
Concat('<b>LookUpName</b>:<br>', group_concat(F.LookUpValue separator '<br>'))
from MainTable J left join
LookUpTable L
on J.ID = L.JobID left join
LookUpValuesTable F
on F.ID = L.FilterID
group by J.ID;
The problem with your query is a MySQL (mis)feature. The on clause is optional for an inner join. Don't ask me why the MySQL designers thought inner join and cross join should be syntactically equivalent. Every other database requires an on clause for an inner join. It is easy enough to express a cross join using on 1=1.
However, the on clause is required for the left join, so when you switch to a left join, the compiler has a problem with the unorthodox syntax. The real problem is a missing on clause; this just happens to show up as "I wasn't expecting a group by yet." Using more traditional syntax with each join followed by an on should fix the problem.
I have problem with select from two tables and left join to third. Query:
SELECT
c.id AS currency, u.user, us.enabled AS currency
FROM
users AS u,
currency AS c
LEFT JOIN users_settings AS us ON(c.id=us.currency, u.user=us.user)
WHERE
c.off=0 AND c.disabled=0 AND c.status=1
Error:
#1054 - Unknown column 'u.user' in 'field list'
I need Cartesian product of users and currency.
Users: id, login, email, pass
http://en.wikipedia.org/wiki/Cartesian_product
You are mixing explicit and implicit join syntax. Try this:
SELECT c.id AS currency, u.user, us.enabled AS currency
FROM currency AS c LEFT JOIN
users_settings AS us
ON c.id = us.currency LEFT JOIN
users u
on u.user = us.user
WHERE c.off = 0 AND c.disabled = 0 AND c.status = 1 ;
MySQL does not necessarily allow the fields to be known over a ,. Scoping is one of the differences between , and cross join. In any case, though, you should use a separate on clause for each join.
Here is the description in the documentation:
INNER JOIN and , (comma) are semantically equivalent in the absence of
a join condition: both produce a Cartesian product between the
specified tables (that is, each and every row in the first table is
joined to each and every row in the second table).
However, the precedence of the comma operator is less than of INNER
JOIN, CROSS JOIN, LEFT JOIN, and so on. If you mix comma joins with
the other join types when there is a join condition, an error of the
form Unknown column 'col_name' in 'on clause' may occur. Information
about dealing with this problem is given later in this section.
Instead of trying to really understand what this means, just avoid using , in the from clause. It is not ever needed.
The query I'm using calls on a few tables in the database and works fine. However, when I add line 10 to the mix it returns 50 or more repeated results. I'm still somewhat new to SQL and Sequel Pro so I'm sure the solution isn't too complicated but I am truly stumped right now.
Here is the code:
SELECT c.first_name, c.last_name, ca.company, ca.city, ca.state, ct.certificate_number, ct.certificate_date
FROM customer c, customer_type ctype, cust_address ca, certification ct, cust_prof_cert cp
WHERE ca.id_customer = c.id_customer LIKE cp.prof_cert_id_prof_cert
AND c.customer_type_id_customer_type = ctype.id_customer_type
AND ct.customer_id_customer = c.id_customer
AND ca.id_customer = c.id_customer
AND ctype.customer_type IN('CIRA','CIRA, CDBV')
AND ct.course_type_id_course_type = 1
AND ct.certificate_number IS NOT NULL
AND cp.prof_cert_id_prof_cert = "1"
ORDER BY ct.certificate_number ASC, c.last_name ASC;
Thank you for your time.
By Doing your SQL like that you are not relating the data, just selecting it. I would recommend changing your SQL to use JOINS.
SELECT Orders.OrderID, Customers.CustomerName, Orders.OrderDate
FROM Orders
INNER JOIN Customers
ON Orders.CustomerID=Customers.CustomerID;
Here is an article that might be able to help you a bit: w3schools, Joins
Here's your query using the SQL92 syntax for joins. You should use this syntax instead of the SQL89 "comma-style" joins.
SELECT c.first_name, c.last_name, ca.company, ca.city, ca.state,
ct.certificate_number, ct.certificate_date
FROM customer AS c
INNER JOIN customer_type AS ctype ON c.customer_type_id_customer_type = ctype.id_customer_type
INNER JOIN cust_address AS ca ON ca.id_customer = c.id_customer
INNER JOIN certification AS ct ON ct.customer_id_customer = c.id_customer
INNER JOIN cust_prof_cert AS cp -- what's this join condition?
WHERE ca.id_customer = c.id_customer LIKE cp.prof_cert_id_prof_cert
AND ctype.customer_type IN('CIRA','CIRA, CDBV')
AND ct.course_type_id_course_type = 1
AND ct.certificate_number IS NOT NULL
AND cp.prof_cert_id_prof_cert = '1'
ORDER BY ct.certificate_number ASC, c.last_name ASC;
A few weird things I notice in this query:
The first term in the WHERE clause is strange. You should know that LIKE has higher precedence than = so this might not be doing what you think it's doing. It's as if you wrote
WHERE ca.id_customer = (c.id_customer LIKE cp.prof_cert_id_prof_cert)
Which means evaluate the LIKE and produce a 0 or a 1 to represent the boolean condition. Then look for a ca.id_customer matching that 0 or 1.
Given that strange term, I can find no other join condition for the cp table. The default join if you give no restriction for it is that every row matches every row in the joined tables. So if you have 50 rows where cp.prof_cert_id_prof_cert = 1, then it will effectively multiply the results from the rest of the joined tables by 50.
This is called a Cartesian product, or in MySQL parlance it's counted in SHOW STATUS as a Full join.
ctype.customer_type IN('CIRA','CIRA, CDBV') You have quoted the second and third strings together. Basically, this means you are trying to match the column against two strings, one of which happens to contain a comma.
You probably meant to write ctype.customer_type IN('CIRA','CIRA','CDBV') so the column may match any of these three values.
I would suggest not querying multiple tables in your FROM clause, I believe this is the cause of your duplicate rows. If you separate out the tables into separate inner or left joins, (whichever you need) you should be able to match which ever keys in each table manually, instead of having SQL attempt to automatically do this.
i'm trying the following MySQL query to fetch some data:
SELECT m.*, t.*
FROM memebers as m, telephone as t
INNER JOIN memeberFunctions as mf ON m.id = mf.memeber
INNER JOIN mitgliedTelephone as mt ON m.id = mt.memeber
WHERE mf.function = 32
But i always get the following error:
#1054 - Unknown column 'm.id' in 'on clause'
The column does exists and the query works fine with only one table (e.g. when i remove telephone)
Does anybody know what I do wrong?
According to this link, you shouldn't mix up both notations when building up joins. The comma you are using to join memebers as m, telephone as t, and the subsequent calls to inner join, are triggering the unknown column error.
To deal with it, use CROSS/INNER/LEFT JOIN instead of commas.
Previously, the comma operator (,) and JOIN both had the same
precedence, so the join expression t1, t2 JOIN t3 was interpreted as
((t1, t2) JOIN t3). Now JOIN has higher precedence, so the expression
is interpreted as (t1, (t2 JOIN t3)). This change affects statements
that use an ON clause, because that clause can refer only to columns
in the operands of the join, and the change in precedence changes
interpretation of what those operands are.
For pedagogic purpose, I'm adding the query as it, I think, should be:
SELECT m.*, t.*
FROM memebers as m
JOIN telephone as t
JOIN memeberFunctions as mf ON m.id = mf.memeber AND mf.function = 32
JOIN mitgliedTelephone as mt ON m.id = mt.memeber
Since you're not joining t and m, the final result will be a cartesian product; you might want it to be revised.
I Hope it helped.
It seems your requirement is to join members table but you are joining with telephone table. just change their order.
SELECT
`m`.*,
`t`.*
FROM
`memebers` AS `m`
JOIN `telephone` AS `t`
JOIN `memeberFunctions` AS `mf`
ON `m`.`id` = `mf`.`memeber`
AND `mf`.`function` = 32
JOIN `mitgliedTelephone` AS `mt`
ON `m`.`id` = `mt`.`memeber`;
Hope this helps you. Thank you!!