I have to convert an Access query to Sql Server query.
In my FROM clause I have something like this:
FROM
(table1 INNER JOIN table2 ON table1.afield = table2.afield)
I'm think that my FROM clause in Sql Server should remain unchanged but I'm not sure about that.
Can you please give me confirm about that?
You can use what you have, I'd take out the parenthesis though;
FROM table1
INNER JOIN table2
ON table1.afield = table2.afield
It would also be a good idea to get into the habit of using table aliases too, something like this;
FROM table1 AS t1
INNER JOIN table2 AS t2
ON t1.afield = t2.afield
As this will help the readability of the code.
Related
Is it possible to join three tables in this way .
select T1.[...],T2.[...],T3.[...]
from T1
full outer join T2 on T1.[key]=T2.[key]
full outer join T3 on T1.[key]=T3.[key]
full outer join T2 on T2.[key]=T3.[key]
My question is : Is this a valid Form?
And if no is there a way to do such operation?
It is "valid" but the full joins are not correct. The on conditions will change them to some other type of join.
Your query has other errors. But I speculate that you want:
select T1.[...], T2.[...], T3.[...]
from T1 full join
T2
on T2.[key] = T1.[key] full join
T3 join
on T3.[key] = coalesce(T2.[key], T1.[key]);
It is possible to join three tables, and your example could run with some changes, but you have syntax and scoping errors in the FROM clause.
Even those aside, I don't think it will do what you intend it to do. You'll probably want to use GROUP BY
See the examples / discussion here :
Multiple FULL OUTER JOIN on multiple tables
I also used this site as a source, as its been a while since I've touched SQL, it may be helpful to you also :
https://learnsql.com/blog/how-to-join-3-tables-or-more-in-sql/
I'm starting to handle an old database that was generated years ago with ACCESS. All the queries have been designed with the ACCESS query wizard and they seem to be very time consuming and I would like to improve their performance.
All queries depend on at least three subqueries and I would like to rewrite the SQL code to convert them into a single query.
Here you have an example of what I'm talking about:
This is the main query:
SELECT Subquery1.pid, Table4.SIB, Subquery1.event,
Subquery1.event_date, Subquery2.GGG, Subquery3.status FROM Subquery1
LEFT JOIN ((Table4 LEFT JOIN Subquery2 ON Table4.SIB =
Subquery2.SIB) LEFT JOIN Subquery3 ON Table4.SIB = Subquery3.SIB)
ON Subquery1.pid = Table4.PID;
This main query depends on three subqueries:
Subquery1
SELECT Table2.id, Table2.pid, Table2.npid, Table3.event_date,
Table3.event, Table3.notes, Table2.other FROM Table2 INNER JOIN Table3
ON Table2.id = Table3.subject_id WHERE (((Table2.pid) Is Not Null) AND
((Table3.event_date)>#XX/XX/XXXX#) AND ((Table3.event) Like "*AAAA" Or
(Table3.event)="BBBB")) ORDER BY Table2.pid, Table3.event_date DESC;
Subquery2
SELECT Table1.SIB, IIf(Table1.GGG Like "AAA","BBB", IIf(Table1.GGG
Like "CCC","BBB", IIf(Table1.GGG Like "DDD","DDD","EEE"))) AS GGG FROM
Table1;
Subquery3
SELECT Table5.SIB, Table5.PID, IIf(Table5.field1 Like
"1","ZZZ",IIf(Table5.field1 Like "2","ZZZ",IIf(Table5.field1 Like
"3","ZZZ",IIf(Table5.field1 Like "4","HHH",IIf(Table5.field1 Like
"5","HHH",IIf(Table5.field1 Like "6","HHH","UUU")))))) AS SSS FROM
Table5;
Which would be the best way of improving the performance of this query and converting all the subqueries into a single statement?
I can handle each subquery, but I'm having a hard time joining them together.
If this:
Table5.field1 Like "3"
is really how some of your subqueries are written (without actual wild characters) you can save a lot of time by changing it to
Table5.field1="3"
'''you can create transient tables for each sub query'''
CREATE Transient table1 AS
'''Your sub query goes here'''
CREATE Transient table2 AS
'''Your sub query goes here'''
'''Main query to merge them into one'''
SELECT '''column names'''
FROM
table1
LEFT JOIN table2
ON table1.common_column = table2.common_column
LEFT JOIN table3
ON table1.common_column = table3.common_column
'''similarly you can combine all sub queries/transient tables'''
SELECT
Trs.itemID, Trs.imtName, Trs.sumQty, Sum(whiQty)
FROM
((SELECT
trsitemID AS itemID, trsimtName AS imtName,
Sum(trsQty) As sumQty
FROM
tblTransactionSub AS T
WHERE
trstraID = 1231
AND trsActive = True
GROUP BY
trsitemID, trsimtName) AS Trs
INNER JOIN
tblWarehouseItem AS WHI ON Trs.itemID = WHI.whiitemID)
RIGHT JOIN
WHI ON Trs.trswhiID = WHI.whiID
WHERE
whiActive = True
AND whiCansel = False
AND whiwrhID = 19
GROUP BY
Trs.itemID,Trs.imtName, Trs.sumQty
HAVING
SUM(whiQty) < Trs.sumQty
If you please help me me out since I am new to SQL commands I can not easily find my mistake.
Thanks in advance
The error that occurred when I added the Right Join is:
Join expression not supported
In MS Access, you have to use parenthesises with multiple joins:
select ...
from
((table1
... join table2 on ...)
... join table3 on ...)
... join tableN
/edit/
As OP question changes its syntax often, then my answer seems out of place :) Initially there were no parens there.
About RIGHT JOIN: You need to use table name (or entire subselect) after JOIN keyword, not skip it or use some other alias. Your query part
RIGHT JOIN
WHI ON Trs.trswhiID = WHI.whiID
currently uses alias WHI, which is wrong in two ways: 1) it is not table name 2) it is already used. You need something like this:
RIGHT JOIN
tblWarehouseItem AS WHI2 ON Trs.trswhiID = WHI2.whiID
It could be possible that MS Access restricts your kind of JOINs usage (like INNER join should not come after LEFT join); I have currently no possibility to check precise rules.
Your problem is that you have no table name after the RIGHT JOIN:
RIGHT JOIN
ON Trs.trswhiID = WHI.whiID
Should be:
RIGHT JOIN YOURTABLENAMEHERE as alias
ON Trs.trswhiID = WHI.whiID
However, you have already defined Trs and Whi, so I have no idea what table you want there, or why. Perhaps you just want to change the INNER JOIN to a LEFT JOIN or RIGHT JOIN.
some one have asked me the output of below query.
Select *
from TableA t1, TableB t2
where t1.Id *= t2.Id
Can anyone explain me, if such type of any query exists, if so then how its works. Because i have never seen such type of query Thanks.
UPDATE:
Also when i run this query in SQL Server, i get this;
The query uses non-ANSI outer join operators ("*=" or "=*").
To run this query without modification, please set the compatibility level
for current database to 80, using the SET COMPATIBILITY_LEVEL option
of ALTER DATABASE.
It is strongly recommended to rewrite the query using ANSI outer join
operators (LEFT OUTER JOIN, RIGHT OUTER JOIN).
In the future versions of SQL Server, non-ANSI join operators will
not be supported even in backward-compatibility modes.
Using asterisk in a WHERE is an old non-ANSI compliant syntax for OUTER JOINing tables and therefore should not be used anymore.
Here's the link.
The asterisk in the where condition is actually part of a non-ANSI outer join operator, it is used to define an implicit outer join.
It will cause trouble in modern databases as this operator has been obsolete since 1992.
Essentially the below are the same:
SELECT * FROM TableA LEFT OUTER JOIN TableB ON t1.Id = t2.Id
SELECT * FROM TableA , TableB WHERE t1.Name *= t2.Name
The *= operator means LEFT OUTER JOIN.
If this works:
SELECT COUNT(t1.ID) AS count FROM Project t1
INNER JOIN (SELECT DISTINCT t.Site,t.id FROM _Equipment_id t WHERE t.OEM LIKE '%ABC%') t2 ON t1.Site=t2.Site AND t1.id=t2.id
and this works:
SELECT COUNT(t3.ID) AS count FROM Wall t3
INNER JOIN Project t1 ON t3.Project_number=t1.Project_number
Why doesn't this work:
SELECT COUNT(t3.ID) AS count FROM Wall t3
INNER JOIN Project t1 ON t3.Project_number=t1.Project_number
INNER JOIN (SELECT DISTINCT t.Site,t.id FROM _Equipment_id t WHERE t.OEM LIKE '%ABC%') t2 ON t1.Site=t2.Site AND t1.id=t2.id
Ultimately, I have 10 tables like the Wall table that I am trying to get a total count from the first SELECT....
SELECT COUNT(t3.ID) AS count FROM Wall t3
INNER JOIN (Project t1
INNER JOIN (SELECT DISTINCT t.Site,t.id FROM _Equipment_id t WHERE t.OEM LIKE '%ABC%') t2
ON t1.Site=t2.Site AND t1.id=t2.id)
ON t3.Project_number=t1.Project_number
Maybe it's just a syntax error? Office Help at the bottom where they mention nesting. The other possibility is that the aliases are somehow scoped so that they are not available to the join, but I'm no expert on MS Access. Maybe you should just try dropping the aliases altogether.
You have a couple of minor issues with your code: a table name that starts with an underscore character (_Equipment_id) and an AS clause ("alias") that is a SQL keyword (AS count). When these are corrected, your SQL is valid SQL-92 syntax.
Sadly, the problem is that Access (ACE, Jet, whatever) does not support the SQL-92 Standard. Access insists that each nested JOIN clause is put in parentheses.
[Aside: JOINs in parentheses are allowed in Standard SQL because it can potentially change the query results. However Access, does not respect the order specified by the coder and allows itself to evaluate JOINs in order it sees fir. So not only Access's syntax non-compliant with the Standard, there is also a loss of functionality! However, this further problem with Access will have no ill effect for this particular query.]
You have two JOINs in the same scope here:
...
INNER JOIN Project t1 ON t3.Project_number=t1.Project_number
INNER JOIN
...
Your code needs to work around Access's problem by enclosing the JOIN in parentheses; because all your JOINs are INNER flavour, it probably doesn't matter where they go.
Also, as regards correcting your AS clause, Access again doesn't support Standard SQL's quoted identifiers (...AS "count"...) and insists you use its proprietary square brackets syntax (...AS [count]...) -- of course, you could choose a different name but there may exist application code that relies on it.
Code to workaround both Access problems:
SELECT COUNT(t3.ID) AS [count]
FROM (Wall t3
INNER JOIN Project AS t1
ON t3.Project_number = t1.Project_number)
INNER JOIN (
SELECT DISTINCT t.Site,t.id
FROM _Equipment_id AS t
WHERE t.OEM LIKE '%ABC%'
) AS t2
ON t1.Site = t2.Site
AND t1.id = t2.id;