What is the better practice when joining tables in a query example 1 or 2? I've always joined tables together like example 2, but it seems that many people are advocates of example 1. Are there any differences performance wise between the two?
Example 1:
SELECT *
FROM authors AS a INNER JOIN publishers AS p
ON a.city = p.city
ORDER BY a.au_lname DESC
Example 2:
SELECT *
FROM authors AS a, publishers AS p
WHERE a.city = p.city
ORDER BY a.au_lname DESC
Hi,
I was having a conversation with another developer about the order that the join conditions are placed. More specifically, about the order the tables are referenced in the join condition. There are two ways to do it, for example:-- Here the table that is referenced first was "declared" first.
SELECT*
FROM
Logon
LEFT OUTER JOIN
Thread
ON Logon.LogonID = Thread.LogonID
LEFT OUTER JOIN
Message
ON Thread.ThreadID = Message.ThreadID
-- Here the table that is referenced first is the table being joined directly above it.
SELECT*
FROM
Logon
LEFT OUTER JOIN
Thread
ON Thread.LogonID = Logon.LogonID
LEFT OUTER JOIN
Message
ON Message.ThreadID = Thread.ThreadID
I realize this is not that big of a deal, but I was wondering if anyone had a good/valid reason for doing one versus the other.
Just curious,
-Ryan
I have 2 tables:
Table 1 has:ID,FName,Lname
Table2 has:ID,PID,PFName,PLName, Flag
PID is a unique number -> (hh:mm:ss)
I need to run an update to table2 by setting the Flag to 1 and also creating PID.
I could use a join query to do this, but I am concern about PID (hh:mm:ss), because it may take less then 1 second to update and I will have duplicate PID.
Any idea what is the best way of doing this?
Well, its kind of tricky, and i got into this.For example i have a column of zip, all US city state name and abbreviation, preffered name and an alternate name of each city in US, and also non-acceptable name of each preffered name..
Can you give me a hint, how many databse should i used?
for example, i search for a zip code, and the result will be the name of city or an acceptable name of city and there are non-acceptable name too..
well.i just need your opinion..hope you could get into this one.tnx
This is more a theoretical question so I do not have any DDL (working)to post.Let's say that I have a query which needs to be filtered for specificaccounts while also needing several joins to retrieve additional data.Is it better to so one big SELECT / JOIN / WHERE statement? As inSELECT * FROM T1JOIN T2 ON T2.[Col1] = T1.[Col1]JOIN T3 ON T3.[Col2] = T1.[Col2] AND T3.[Col3] = T1.[Col3]and so on...WHERE T1.[Account] IN ('123', '456', '789')OR is it better to do an inner SELECT / WHERE and pass that to a SELECT/ JOIN? As inSELECT * FROM(SELECT * FROM T1WHERE T1.[Account] IN ('123', '456', '789')) ITJOIN T2 ON T2.[Col1] = IT.[Col1]JOIN T3 ON T3.[Col2] = IT.[Col2] AND T3.[Col3] = IT.[Col3]and so on...First glance logic says that the inner select is the way to go sincethe joins would have less rows to work with, as opposed to joineverything and THEN pulling out what is not needed. But the queryplanner sometimes seems to have a mind of its own... Does it know thatrows will be pulled so it does that first? If I follow the same"structure" with many different queries does in us the same logic allthe time or do I need to try the same thing for each and check it?How does this apply to situations where there is a UNION involved? Do Ido the union and then apply WHERE and JOIN to filter out rows and getadditional data, respectively, or do I filter out rows inside the unionand take the combined set and do the JOINS?SELECT * FROM(SELECT T1.[Col1], T1.[Col2] FROM T1UNION ALLSELECT T2.[Col1], T2.[Col2] FROM T2) CTJOIN T2 ON T2.[Col1] = CT.[Col1]JOIN T3 ON T3.[Col2] = CT.[Col2] AND T3.[Col3] = CT.[Col3]and so on...WHERE CT.[Account] IN ('123', '456', '789')versusSELECT * FROM(SELECT T1.[Col1], T1.[Col2] FROM T1 WHERE T1.[Account] IN ('123','456', '789')UNION ALLSELECT T2.[Col1], T2.[Col2] FROM T2 WHERE T2.[Account] IN ('123','456', '789')) CTJOIN T2 ON T2.[Col1] = CT.[Col1]JOIN T3 ON T3.[Col2] = CT.[Col2] AND T3.[Col3] = CT.[Col3]and so on...
View 2 Replies View RelatedHi,
I need your suggestions on a design issue:
I have 2 tables, Customers and Organizations. 1 Customer can be under many organizations. What would be the best way to design the db (2 choices) for performance (around 50000 customers):
1)
-Customer table
-Organization table
-Link Organization & Customer by creating a new tables with the following structure ---> CustomerID, OrgID,
2)
-A Customer tables that has a field called OrgID where the orgID is stored. If the customer has more organization related to him, we add another customer record and we put the new OrgID in the OrgID column. Examples:
Customer Table
--------------
CustomerID--Fname--Lname--Addresss-----OrgID
---------------------------------------------
1 Bob Marley 33 Africa org1
1 Bob Marley 33 Africa org2
1 Bob Marley 33 Africa org3
Please give me your suggestions,
Thank you for your time,
SASAN
I need to purchase a new computer for a small medical clinic which will basically only have one purpose: to answer to read and write queries to a SQL Server 2005 which is resident on that computer. Queries come from the current 8 stations (up to 14 stations in the future). Most of the time, only 3 stations will be active at a time. Queries are mostly to access patient file information, are not complex and are short-lived.
A friend of mine who owns a computer store just quoted me for a dual quad-core Xeon 5405 2GHz system with Windows Server 2003 10 Cals. I'm concerned about the following:
- What's the use in having 8 cores, each of them running at only
2GHz, when there's really only one service running (SQL Server
2005, likely Express Edition) on the computer. Does SQL Server
have the capability to make use of all cores? Otherwise, why
spend more for Xeon and so many cores instead of a single
C2D running at a faster speed of say 3GHz ?
- What would be the advantage of using a Windows Server over
Windows XP in a peer-to-peer configuration? I don't buy into
the 10 connection limit because the TCPIP.sys file can be
altered to move that limit up, so 14 stations does not trigger
the need for Windows Server in and of itself.
Thanks all!
Hi all,
I am having problem with SQL connection at Godaddy where my pool connection gets MAX OUT. When it happens, I cannot access the database.This is the thread about the problem: http://forums.asp.net/thread/1665023.aspx
I just created this with "THREAD". I hope someone who has experiences with thread can give me some advice about my design. This is my first time.
static object Locked = new object();
public object ExecuteCommand(string queryStr, string type){ //*************************************************************************************// // ExecuteCommand: Returns an object // //*************************************************************************************// Thread t = null; lock(Locked) { SQLString = queryStr; switch(type) { case "ExecuteNonQuery": t = new Thread(ExecuteNonQuery); break; case "ExecuteScalar": t = new Thread(ExecuteScalar); break; case "GetDataReader": t = new Thread(GetDataReader); break; } t.Start(); t.Join(); } return null;}
First of, does this work at all? It runs, but is it a good design in term of Thread? Since I use LOCK, do I still need the t.Join() function? The switch with the three cases, is that OKAY? Basically, I'm clueless. If you read my other post, you will get an idea what I'm trying to do. Any feedback would be very very appreciated.
Thank you.
Hi,
I was talking to my boss to day and our report request are not very consistant. We always having someone coming back to change something in our report. We were thinking of useing something called the Cube Analysis. Then it give our employees the raw data for them to run any standard query for themself. We have folks that want a report one way, but then they changed their minds and we are creating yet another report 4 or 5 times. what are your thoughts about this type of database?
What's the current opinion on UDTs? Are they valuable? Do the benefits outweigh the costs? Are they an absolute no-no? Has there been anything authorative or groundbreaking on the topic since Alex P's blog back in October 2005?
http://weblogs.asp.net/alex_papadimoulis/archive/2005/10/20/428014.aspx
I need some other opinions on whether or not this is considered a proper database design structure.
Here is the relationship...We have PEOPLE, that each can belong to a COMPANY.
PERSON_TABLE
Person_ID
Company_ID
COMPANY_TABLE
Company_ID
Then each person can trust other people of other companies, but can only trust 1 person per company.
My question is this. In order to maintain a constraint of 1 person per company, is it considered OK to add a the redundant column Company_ID to the PERSON_TRUSTED_TABLE(and then creating a composite primary key on the Person_ID/Company_ID) instead of just adding a trigger to the PERSON_TRUSTED_TABLE to uphold the constraint.
PERSON_TRUSTED_TABLE
Person_ID
Trusted_Company_ID
Trusted_Person_ID
I would appreciate anyone's opinion. Thanks so much!
I am not that experienced in SQL 2005 and I'm trying to debug a stored proc (written by a far more experienced programmer which is why I'm appending here.)
At the top of the proc is the statement 'DECLARE @BillActualRoom bit'. If I understand correctly this is a local variable.
Later in the code we have the statement
'SELECT @BillActualRoom = 0 FROM BillingOptions WHERE CenterID = @CenterID'
where @CenterID is an input parameter.
The table BillingOptions does have a field called 'BillActualRoom' and it is a bit.
My question is this: Does this SQL statement make any sense at all? (My gut reaction is no but I'd like a second opinion. Can't get any consensus in the office.)
I would think that putting a local variable in like this would mean that @BillActualRoom is always equal to 0.
Trying to deal with a user complaint of slowness. Many variables looked at which look normal (Buffer cache, queue length,memory). Probably looks like a network issue. My question is what people consider acceptable when it comes to %disk time. My %disk time has increased from an average of 20% to 33% in recent months. My average disk read and average disk write have both been less than one. MY research has showed that more than 55% %disk time for ten minutes is considered a problem. Not there yet but seem to be slowly getting there. THe app running against my server is vendor written so can't change, also running log shipping which is probably inflating the numbers a little.
Any opinions appreciated.
I have a server with little control over most of the codeset and db design. Recently I have seen both the Processor - %Processor time and Processor - % User time go fom about 6.3 to about 24.3. The system queue length has also gone from about .2 to 1.1. In my humble opinion both of the are signs of a problem coming (luckily the cache hit ratio is still sitting at about 99%). I have been running profiler to catch the things that take more that 4500 MS, and I can probably tie the 2 together. Any opinions, or real world comparisons appreciated
View 3 Replies View RelatedWe are trying to restrict developer permissions in our development environment. One thought is to add developers to db_datareader, db_datawriter, db_ddladmin, db_securityadmin and then revoke various permissions from ddladmin and securityadmin. The goal is to allow developer to create stored procedures and assign permissions to the stored procedures.
Another option is to place all developers in the same role and ask them to create all procedures using that role name (ex: dev_role.sp_procedurename). By doing this each developer will be able to run stored procedures created by another developer. The down side is the permissions do not match Model Office/User Test and Production.
Any suggestions on how to handle this situation?
Thanks, Dave
i've a database where relations are hold in a special way which the projectleaders think of as "performant and uncomplicated" but which is veryquestionable to me:------------------------------------------------Table [Attributes]Fields [AttributeID] and [AttributeText]Table [Objects]Fields object stuff.... and [AttributeIDs] (varchar with 0-20 ids usually)in AttributeIDs there is a backslash separted list of Attribute-IDs like'3412278'so to get 20 object with a special attribute (which we need often) we doSELECT TOP 20 *FROM ObjectsINNER JOIN AttributesON (Objects.AttributeIDs LIKE ('%' + (CAST AttributeID AS varchar) + '\%'))ORDER BY ObjectTextps: to store data we need for communication we include a dozen of fields in*every* table and its content makes about 100 bytes/record------------------------------------------------i would do this stuff with a table to store the object/attributecorrelations.could someone tell me if that stuff makes any sense to an expert and how tovaluate it in regard of performance(we have big customers where that *is* anissue), design, scalability, pragmatism and sense ;)thanks in advance,ViperDK
View 1 Replies View RelatedDear friends,
I need your feedback, tips and opinions to improve my dataflow described in my blog.
http://pedrocgd.blogspot.com/2007/07/ssis-dataflow-performance-i.html
Thanks!!
I inherited this website from a previous developer that uses an Access DB as a backend. Ugh. Apparently, he was extremely limited in what databases he could use. The website is filled with problems related to connecting to this database, which is no surprise. Most of them are related to permissions to the database file, multiple user access, etc. I am thinking about moving this to a SQL Server Express DB and upgrading the site to the 2.0 framework. Most of my experience is in SQL Server, but since they can't, or won't, pay for the SQL Server Database, is this a good solution? I've considered using MySQL as well, but their host won't provide support for this. Are there any other recommended alternatives?
View 2 Replies View RelatedHi, i need an opinion on this...to prevent the duplicate record in db,i am using unique constraints for a column or combination of column as the case may be.By reading this article http://aspalliance.com/687_Preventing_Duplicate_Record_Insertion_on_Page_Refresh.5 , i get the feeling that its not such a good idea..i am wondering,what does it imply?Does it mean that unique constraints are not reliable enough?Does it mean,it may break and let the duplicate record inserted,even though its not suppose to?I am using SQL server 2005
I have read Dino's article on dup recs and i have still not understood it completely.. i am looking for some not so complex ,full proof method,to prevent duplicate record insertion by clicking refresh or multiple (careless)clicking on submit....thanks ..
I have about a 35000 record table. There are about 14 entries in this table that relate to "sections". Each of these sections can have up to 20 values. This lends itself to a design like:
big_table [one-to-one] big_table_has_sections [many-to-many] sections
or, more concretely:
BuildingConstructionType
relates to
ConstructionHasTypes
relates to
Types
Where BuildingConstructionType is one of 14 fields in the 35000 record "big" table, ConstructionHasTypes is the one-to-one intermediary relation that relates many-to-many with Types (the sections).
Unfortunately, with 35000 records, this big_table_has_sections seems like it might bloat. Is this a good solution?
Hi to everyone,My problem is, that I'm not so quite sure, which way should I go.The user is inputing by second part application a long string (let'ssay 128 characters), which are separated by semiclon.Example:A20;BU;AC40;MA50;E;E;IC;GREENNow: each from this position, is already defined in any other table, asa separate record. These are the keys lets say. It means, a have someproperities for A20, BU, aso.Because this long inputed string, is a property of device (whih alsohas a lot of different properities) I could do two different ways ofstoring data:1. By writing, in SP, just encapsulate each of the position separatedby semicolon, and write into a different table with index of device,and the position in long stirng nearly in this way:Major device data tableID AnyData1 AnyData2 ... AnyData3123 MZD12 XX77 .... any comment text124 MZD13 XY55 ... any other commentString data Tablefk_deviceId position value123 1 A20123 2 BU123 3 AC40.....123 8 GREENThe device table, contains also a pointer (position), which mightchange, to "hglight" specified position.Then, I can very easly find all necessary data. The problem is, I needto move the device record data (from other table) very often into otherhistory table (by each update). That will mean, that I also need tomove all these records from 1 -8 for example to a separate historytable, holding the index for a history device dataset. This is a littleinconvinience in this, and in my opinion, it will use to much storagedata, and by programming, I need always to shift this properities intohistory table, whith indexes to a history table of other properities.2. Table will be build nearly in this way:Major device data tableID AnyData1 AnyData2 ... AnyData3 stringProperty pointer123 MZD12 XX77 .... any comment text A20;BU;AC40;MA50;E;E;IC;GREEN 3124 MZD13 XY55 ... any other comment A20;BU;AC40;MA50;E;E;IC;GREEN 2By writng into device table, there will be just a additional field forthis string, and I will have a function, which according to specifiedpointer, will get me the string part on the fly, while I need it.This will not require the other table, and will reduce the amout ofdata, not a lot ... but always.This solution, has a inconvinance, that it will be not so fast doing asearch over the part of this strings, while there will be no real indexon this.If I woould like to search all devices, by which the curent pointervalue is equal GREEN, then I need to use function for getting thevalue, and this one will be not indexed, means, by a lot amount ofdata, might be slow.I would like to know Your opinion about booth solutions.Also, if you might point me the other problems with any of thissolution, I might not have noticed.With Best RegardsMatik
View 7 Replies View RelatedHello
Can any one tell me the difference between Cross Join, inner join and outer join in laymans language
by just taking examples of two tables such as Customers and Customer Addresses
Thank You
I have two xml source and i need only left restricted data.
how can i perform left restricted join?
I was writing a query using both left outer join and inner join. And the query was ....
SELECT
S.companyname AS supplier, S.country,P.productid, P.productname, P.unitprice,C.categoryname
FROM
Production.Suppliers AS S LEFT OUTER JOIN
(Production.Products AS P
INNER JOIN Production.Categories AS C
[code]....
However ,the result that i got was correct.But when i did the same query using the left outer join in both the cases
i.e..
SELECT
S.companyname AS supplier, S.country,P.productid, P.productname, P.unitprice,C.categoryname
FROM
Production.Suppliers AS S LEFT OUTER JOIN
(Production.Products AS P
LEFT OUTER JOIN Production.Categories AS C
ON C.categoryid = P.categoryid)
ON
S.supplierid = P.supplierid
WHERE
S.country = N'Japan';
The result i got was same,i.e
supplier country productid productname unitprice categorynameSupplier QOVFD Japan 9 Product AOZBW 97.00 Meat/PoultrySupplier QOVFD Japan 10 Product YHXGE 31.00 SeafoodSupplier QOVFD Japan 74 Product BKAZJ 10.00 ProduceSupplier QWUSF Japan 13 Product POXFU 6.00 SeafoodSupplier QWUSF Japan 14 Product PWCJB 23.25 ProduceSupplier QWUSF Japan 15 Product KSZOI 15.50 CondimentsSupplier XYZ Japan NULL NULL NULL NULLSupplier XYZ Japan NULL NULL NULL NULL
and this time also i got the same result.My question is that is there any specific reason to use inner join when join the third table and not the left outer join.
I have two select statements, in between select statement taking UNION ALL . I need to avoid the error
Warning: The join order has been enforced because a local join hint is used.
Scenario:
OLEDB source 1
SELECT ...
,[MANUAL DCD ID] <-- this column set to sort order = 1
...
FROM [dbo].[XLSDCI] ORDER BY [MANUAL DCD ID] ASC
OLEDB source 2
SELECT ...
,[Bo Tkt Num] <-- this column set to sort order = 1
...
FROM ....[dbo].[FFFenics] ORDER BY [Bo Tkt Num] ASC
These two tasks are followed immediately by a MERGE JOIN
All columns in source1 are ticked, all column in source2 are ticked, join key is shown above.
join type is left outer join (source 1 -> source 2)
result of source1 (..dcd column)
...
4-400-8000119
4-400-8000120
4-400-8000121
4-400-8000122 <--row not joining
4-400-8000123
4-400-8000124
...
result of source2 (..tkt num column)
...
4-400-1000118
4-400-1000119
4-400-1000120
4-400-1000121
4-400-1000122 <--row not joining
4-400-1000123
4-400-1000124
4-400-1000125
...
All other rows are joining as expected.
Why is it failing for this one row?
I'm having trouble with a multi-table JOIN statement with more than one JOIN statement.
For each order, I need to return the following: CarsID, CarModelName, MakeID, OrderDate, ProductName, Total ordered the Car Category.
The carid (primary key) and carmodelname belong to the Cars table.
The makeid and orderdate belong to the OrderDetails table.
The productname and carcategory belong to the Product table.
The number of rows returned should be the same as the number of rows in OrderDetails.
Why would I use a left join instead of a inner join when the columns entered within the SELECT command determine what is displayed from the query results?
View 4 Replies View RelatedI have a merge join (full outer join) task in a data flow. The left input comes from a flat file source and then a script transformation which does some custom grouping. The right input comes from an oledb source. The script transformation output is asynchronous (SynchronousInputID=0). The left input has many more rows (200,000+) than the right input (2,500). I run it from VS 2005 by right-click/execute on the data flow task. The merge join remains yellow and the task never finishes. I do see a row count above the flat file destination that reaches a certain number and seems to get stuck there. When I test with a smaller file on the left it works OK. Any suggestions?
View 3 Replies View RelatedI'm using SQL Server 2005.
A piece of software I wrote starting timing out on a query that left outer joins a table to a view. Both the table and view have approximately the same number of rows (about 170000).
The table has 2 very similar columns, one is a varchar(1) and another is varchar(100). Neither are included in any index and beyond the size difference, the columns have the same properties. One of the employees here uses the varchar(1) column (called miscsearch) to tag large sets of rows to perform some action on. In this case, he had set 9000 rows miscsearch value to "g". The query then should join the table and view for all rows where miscsearch is set to g in the table. This query takes at least 20 minutes to run (I stopped it at this point).
If I remove the "where" clause and join all rows in the two tables, the query completes in about 20 seconds. If set the varchar(100) column (called descrip) to "g" for the same rows set via miscsearch, the query completes in about 20 seconds.
If I force the join type to a hash join, the query completes using miscsearch in about 30 seconds.
So, this works:
SELECT di.File_No, prevPlacements, balance,'NOT PLACED' as status FROM Info di LEFT OUTER HASH JOIN View_PP pp ON di.ram_file_no = pp.file_no WHERE miscsearch = 'g' ORDER BY balance DESC
and this works:
SELECT di.File_No, prevPlacements, balance,'NOT PLACED' as status FROM Info di LEFT OUTER JOIN View_PP pp ON di.ram_file_no = pp.file_no WHERE descrip = 'g' ORDER BY balance DESC
But this does't:
SELECT di.File_No, prevPlacements, balance,'NOT PLACED' as status FROM Info di LEFT OUTER JOIN View_PP pp ON di.ram_file_no = pp.file_no WHERE miscsearch = 'g' ORDER BY balance DESC
What should I be looking for here to understand why this is happening?
Thanks,
john
Awesome! I don't alway get the email notification of whoever reply to the posting. I think it only work after I log off of the forum.
Scott
We are trying to migrate from sql 2005 to 2012. I am changing one of the implicit join to explicit join. As soon as I change the join, the number of rows returned are fewer than before.
Below is my Implict join query
INSERT #RIF_TEMP1 (rf1_row_no,rf1_rif, rf1_key_id_no, rf1_last_date, rf1_start_date)
SELECT currow.rf0_row_no, currow.rf0_rif, currow.rf0_key_id_no, prevrow.rf0_start_date, currow.rf0_start_date
FROM #RIF_TEMP0 currow , #RIF_TEMP0 prevrow
[Code] ....
and below is explict join query
INSERT #RIF_TEMP1 (rf1_row_no,rf1_rif, rf1_key_id_no, rf1_last_date, rf1_start_date)
SELECT currow.rf0_row_no, currow.rf0_rif, currow.rf0_key_id_no, prevrow.rf0_start_date, currow.rf0_start_date
FROM #RIF_TEMP0 currow LEFT JOIN #RIF_TEMP0 prevrow
ON (currow.rf0_row_no = prevrow.rf0_row_no + 1)
[Code] ....
the count returned from both the queries is different.
I am not sure what am I doing wrong. The count of #RIF_TEMP0 is always 32, it never changes, but the variable @countTemp is different for both the queries.
Why does this right join return the same results as using a left (or even a full join)?There are 470 records in Account, and there are 1611 records in Contact. But any join returns 793 records.
select Contact.firstname, Contact.lastname, Account.[Account Name]
from Contact
right join Account
on Contact.[Account Name] = Account.[Account Name]
where Contact.[Account Name] = Account.[Account Name]