this is how i join 2 tables and select form it:
OleDbDataAdapter DataA = new OleDbDataAdapter(#"Select tfr.FeedID, tf.FeedName, tfr.FeedQuantity, tf.DM
FROM tFeeds AS tf
INNER JOIN tFeedsRations AS tfr ON (tf.FeedID=tfr.FeedID)", Connection);
but what about adding a access query to this select command?
for example I want to add this statement to my select command:
Select qfq.FeedDMQuantites
From qFeeds_Quantities as qfq
what should I do?
Well add another JOIN condition to this table qFeeds_Quantities (assuming you have a relationship to this table or a common column among other table).
Assuming you have a common column like FeedID in this new table as well you can make another JOIN like
select tfr.FeedID, tf.FeedName, tfr.FeedQuantity,
tf.DM, qfq.FeedDMQuantites
FROM (tFeeds AS tf
INNER JOIN tFeedsRations AS tfr ON tf.FeedID = tfr.FeedID)
INNER JOIN qFeeds_Quantities as qfq ON tf.FeedID = qfq.FeedID;
If you want to include another JOIN then parenthesize like
FROM ((tFeeds AS tf
INNER JOIN tFeedsRations AS tfr ON tf.FeedID = tfr.FeedID)
INNER JOIN qFeeds_Quantities as qfq ON tf.FeedID = qfq.FeedID)
INNER JOIN BLAH AS bll ON bll.test = tf.test;
Related
Syntax Error (missing Operator) in query expression 'tbl_employee.emp_id = tbl_netpay.emp_id INNER JOIN tbl_gross ON tbl_employee.emp_id = tbl_gross.emp_ID INNER JOIN tbl_tax ON tbl_employee.emp_id - tbl_tax.emp_ID'.
SELECT tbl_employee.emp_ID,
tbl_employee.emp_name,
tbl_gross.BasicSalary,
tbl_gross.totalOT,
tbl_netpay.totalGross,
tbl_tax.totalLate,
tbl_tax.allowance,
tbl_tax.SSS,
tbl_tax.PhilHealth,
tbl_tax.GSIS,
tbl_tax.HDMF,
tbl_netpay.totalDeduc,
tbl_netpay.emp_ti,
tbl_netpay.emp_wt,
tbl_netpay.emp_np
FROM tbl_employee
INNER JOIN tbl_netpay ON tbl_employee.emp_id = tbl_netpay.emp_id
INNER JOIN tbl_gross ON tbl_employee.emp_id = tbl_gross.emp_ID
INNER JOIN tbl_tax ON tbl_employee.emp_id = tbl_tax.emp_ID;
I always get the error above.
Access requires parentheses in the FROM clause for queries which include more than one join. Try it this way ...
FROM
((tbl_employee
INNER JOIN tbl_netpay
ON tbl_employee.emp_id = tbl_netpay.emp_id)
INNER JOIN tbl_gross
ON tbl_employee.emp_id = tbl_gross.emp_ID)
INNER JOIN tbl_tax
ON tbl_employee.emp_id = tbl_tax.emp_ID;
If possible, use the Access query designer to set up your joins. The designer will add parentheses as required to keep the db engine happy.
Thanks HansUp for your answer, it is very helpful and it works!
I found three patterns working in Access, yours is the best, because it works in all cases.
INNER JOIN, your variant. I will call it "closed set pattern".
It is possible to join more than two tables to the same table with good performance only with this pattern.
SELECT C_Name, cr.P_FirstName+" "+cr.P_SurName AS ClassRepresentativ, cr2.P_FirstName+" "+cr2.P_SurName AS ClassRepresentativ2nd
FROM
((class
INNER JOIN person AS cr
ON class.C_P_ClassRep=cr.P_Nr
)
INNER JOIN person AS cr2
ON class.C_P_ClassRep2nd=cr2.P_Nr
)
;
INNER JOIN "chained-set pattern"
SELECT C_Name, cr.P_FirstName+" "+cr.P_SurName AS ClassRepresentativ, cr2.P_FirstName+" "+cr2.P_SurName AS ClassRepresentativ2nd
FROM person AS cr
INNER JOIN ( class
INNER JOIN ( person AS cr2
) ON class.C_P_ClassRep2nd=cr2.P_Nr
) ON class.C_P_ClassRep=cr.P_Nr
;
CROSS JOIN with WHERE
SELECT C_Name, cr.P_FirstName+" "+cr.P_SurName AS ClassRepresentativ, cr2.P_FirstName+" "+cr2.P_SurName AS ClassRepresentativ2nd
FROM class, person AS cr, person AS cr2
WHERE class.C_P_ClassRep=cr.P_Nr AND class.C_P_ClassRep2nd=cr2.P_Nr
;
I'm trying to select by c# and odbc from the following tables.
LinkTab (FromDevID, FromPort, ToDevID, ToPort)
DevList (ID,DevName...)
The result should look like
FromDevName | FromPort | ToDevName | ToDevPort
i tried already the following statement:
SELECT dev1.DevName, lt.FromPort, dev2.DevName, lt.ToPort
FROM (LinkTab lt
INNER JOIN DevList dev1 ON lt.FromDevID = dev1.ID)
INNER JOIN devList dev2 ON lt.ToDevID = dev2.ID
and I couldn't get all records. I guess there is a mistake at my join condition.
Presumably, you need left join:
SELECT dev1.DevName, lt.FromPort, dev2.DevName, lt.ToPort
FROM (LinkTab lt LEFT JOIN
DevList dev1
ON lt.FromDevID = dev1.ID
) LEFT JOIN
devList dev2
ON lt.ToDevID = dev2.ID;
The reason your query would not return all the rows is because the devises may not always match. If this is the case, then INNER JOIN will filter out the rows with unmatched devices. A LEFT JOIN will keep all the rows in the first table, assigning NULL for the columns from the second and third tables.
I have 3 tables with various columns:
tableA = id(PK) & name columns
tableB = id(PK), A_ID(foreign key to tableA), name, address, etc columns
tableC = id(PK), A_ID(foreign key to tableA), name columns
I’m trying to use the following query to retrieve values from certain columns within all tables based on tableA name = ‘something’, but always returning syntax errors.
“SELECT tableA.name, tableB.name, tableB.address, tableC.name FROM
tableA, tableB, tableC JOIN tableB ON tableA.id = tableB.A_ID JOIN tableC
ON tableA.id = tableC.A_ID WHERE tableA.name = ‘something’”
You have to remove tables from from statement if you want to use join syntax
SELECT tableA.name, tableB.name, tableB.address, tableC.name
FROM tableA
INNER JOIN tableB ON tableA.id = tableB.A_ID
INNER JOIN tableC ON tableA.id = tableC.A_ID
WHERE tableA.name = 'something'
I suggest you to use aliases, the code could be more readable:
SELECT A.name, B.name, B.address, C.name
FROM tableA A
INNER JOIN tableB B ON A.id = B.A_ID
INNER JOIN tableC C ON A.id = C.A_ID
WHERE A.name = 'something'
Ms Access requires you to specify the type of join: INNER; LEFT; or RIGHT. Access does not recognize just JOIN as a synonym for INNER JOIN.
A query which includes more than one join requires parentheses in the FROM clause.
I also changed your quote characters to plain " and '. The sample query included type-setting quotes. I don't know if they are present in the actual SQL, but I would avoid them.
SELECT tableA.name, tableB.name, tableB.address, tableC.name
FROM
(tableA
INNER JOIN tableB
ON tableA.id = tableB.A_ID)
INNER JOIN tableC
ON tableA.id = tableC.A_ID
WHERE tableA.name = 'something'
If you have the full version of Access available, use the query designer to set up the joins. The designer knows the syntax rules which keep the db engine happy.
otherwise you could do it like:
SELECT tableA.name, tableB.name, tableB.address, tableC.name
FROM tableA, tableB, tableC
WHERE tableA.id = tableB.A_ID AND tableA.id = tableC.A_ID
AND tableA.name = ‘something
Parado's answer is correct..
Moreover you can simplify the length of the query by using aliases for the table names.. And it is good practice too..
select a.name, b.name, b.address
from tableA a
join tableB b
on a.id = b.A_ID
I have a list of SiteUsers in one table and another table has columns with different types of owners (ID) for the record. For example, the SiteUserID in the SiteUsers table will be used for the SalesRepID, the StaffingManagerID, and RecruiterID in the Fill table. Of course, the SiteUserID is different for each of the values in the Fill table.
I'd like to return the name of the SiteUser for each ID column in the Fill Table.
How do I properly construct a JOIN statement to do this?
I'm guessing this is done through INNER JOIN, but I'm not sure.
My current select statement already has an INNER JOIN as I'm pulling the name of the FillType from another table. I'm using this in an asp.net application.
I'm not sure if this is even possible. Any help is appreciated.
Since each of the IDs in the Fills table allows null, you probably want to LEFT JOIN to the SiteUsers table like so:
SELECT f.FillID, s1.SiteUserLastName 'SalesRep', s2.SiteUserLastName 'StaffingManager', s3.SiteUserLastName 'Recruiter'
FROM Fills f
LEFT JOIN SiteUsers s1 on f.SalesRepID = s1.SiteUserID
LEFT JOIN SiteUsers s2 on f.StaffingManagerID = s2.SiteUserID
LEFT JOIN SiteUsers s3 on f.RecruiterID = s3.SiteUserID
You can always UNPIVOT the results like so:
SELECT
DISTINCT
unpvt.FillID
,unpvt.RepID
,unpvt.RepType
,s.SiteUserFirstName
,s.SiteUserLastName
FROM
(SELECT
FillID
,SalesRepID
,StaffingManagerID
,RecruiterID
FROM Fills
) f
UNPIVOT
(RepID FOR RepType IN
(SalesRepID, StaffingManagerID,RecruiterID)
) AS unpvt
JOIN SiteUsers AS s on unpvt.RepID = s.SiteUserID`
Obviously you can play with exact output (such as substituting the RepType for a different value with a CASE statement or whatnot.
My question is: why the piss-poor design? Instead of having three IDs in the Fills table, you should have a junction table between SiteUsers and Fills to allow many-to-many relationships. IF it were designed with a junction table, you'd never have had to ask this question.
You will have to join the Fill table with the SiteUsers table multiple times, one for each xxxID column in the Fills for which you want the SiteUser name and combine the results using an union as below:
select a.SiteUserId, a.SiteUserFirstName, a.SiteUserLastName
from dbo.SiteUsers a
inner join dbo.Fills b on b.SalesRepId = a.SiteUserId
UNION
select a.SiteUserId, a.SiteUserFirstName, a.SiteUserLastName
from dbo.SiteUsers a
inner join dbo.Fills b on b.StaffingManagerId = a.SiteUserId
UNION
select a.SiteUserId, a.SiteUserFirstName, a.SiteUserLastName
from dbo.SiteUsers a
inner join dbo.Fills b on b.RecruiterId = a.SiteUserId
This is a two part question and for education purposes rather than trying to find a solution to a problem.
I've seen this already and realize that it's very similar to my question
LINQ2SQL - Cross join emitted when I want inner join
But I am hoping for more information from you LINQ and SQL gurus as to why the cross join is created instead of inner join in LINQ2SQL. Additionally, can someone explain how SQL Server decides on the execution plan (or link to further information) since both of these queries generate the same plan? From what I understand, this means that the performance of the queries are the same.
I've created a small example that runs two LINQ expressions on my database that generates these two different SQL queries.
For those who don't want to bother, here's my example db diagram:
http://dl.dropbox.com/u/13256/Screen%20shot%202011-03-16%20at%2011.41.56%20AM.png
Here are the two queries:
Cross Join with Where Clause
var q = from item in context.Items
join i_mem in context.Memberships on new { item_id = item.ID, user_id =
current_user_id.Value } equals new { item_id = i_mem.RelatedItemID, user_id =
i_mem.RelatedUserID } into sq_i_m
from im in sq_i_m.DefaultIfEmpty()
join i_cat in context.Categories on item.RelatedCategoryID equals i_cat.ID
into sq_i_cat
from proj in sq_i_cat
select item;
Inner Join
from item in context.Items
join i_mem in context.Memberships on
new { item_id = item.ID, user_id = current_user_id.Value }
equals
new { item_id = i_mem.RelatedItemID, user_id = i_mem.RelatedUserID }
into sq_i_m
from im in sq_i_m.DefaultIfEmpty()
join i_cat in context.Categories on item.RelatedCategoryID equals i_cat.ID
select item
And here is the test program if you'd like to see for yourself.
Thanks for everyone's help.
Mustafa
They are the same thing, so it does not matter which LINQ2SQL emits.
An inner join is logically equivalent to a cross join with a where clause filter equivalent to the on of the inner join clause.
That's why Sql Server generates the same query plan.
To be clear, the inner join:
Select f1
From T1 inner join T2 on T1.k = T2.k
where T1.f2 like 'X%'
Is the same as the cross join:
Select f1
From T1 cross join T2
where T1.k = T2.k
and T1.f2 like 'X%'
is the same as old-style SQL:
Select f1
From T1, T2
where T1.k = T2.k
and T1.f2 like 'X%'
Lets say you have a datacontext called MyDataContext.
using(MyDataContext db = new MyDataContext())
{
var q = db.Items.Where(x=> x.Categories.Name == "myCategory").Select(x=> x);
}
This is a very simple example, but you didn't need to write out a join or a subquery in TSQL syntax. (I hate writing TSQL).