Ntext + Nvarchar - Will This Improve Performance?
Jan 28, 2004
Hi all
I have a table that contains an ntext column for storing values up to a couple of Mb in size.
However, I estimate that 95% of the values stored in this ntext field will fit into an nvarchar(4000) field.
Is it worth me having both fields in the table?
i.e. For rows where the values < 4000 characters I would store the value in the nvarchar column. Otherwise I would use the ntext column.
Can anyone confirm whether this technique would increase performance given that ntext values are sort of stored separately to the rest of the table data?
A colleague of mine is an Oracle DBA and he mentioned this technique is fairly caommonly adopted in the Oracle world.
Thanks
Matt
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Nov 28, 2007
I am running this query to an sql server 2000 database from my aspcode:"select * from MyTable whereMySqlServerRemoveStressFunction(MyNtextColumn) = '" &MyAdoRemoveStressFunction(MyString) & "'"The problem is that the replace function doesn't work with the ntextdatatype (so as to replace the stresses with an empty string). I hadto implement the MySqlServerRemoveStressFunction, i.e. a function thattakes a column name as a parameter and returns the text contained inthis column having replaced some letters of the text (the letters withstress). Unfortunately, I could not do that because user-definedfunctions cannot return a value of ntext.So I have the following idea:"select * from MyTable whereCheckIfTheyAreEqualIngoringTheStesses(MyNtextColum n, '" & MyString &"')"How can I implement the CheckIfTheyAreEqualIngoringTheStessesfunction? (I don't know how to combine these functions to do what Iwant: TEXTPTR, UPDATETEXT, WRITETEXT, READTEXT)
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Sep 27, 2005
I am new to SQL Server and would like to hear opinions on pros and cons of using nText vs. nVarChar data type for following uses:
URLs (up to 260 bytes)
Addresses (50-300 bytes)
Descriptions and comments (50-2,000 bytes)
Memos (up to 8000 bytes)
TIA.
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Feb 6, 2007
Hello,
I need to save some news text in an SQL table. The text can be long.
1. Should I use nvarchar(MAX) or nText?
2. And what is the difference between nText and Text?
I am using SQL 2005.
Thanks,
Miguel
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Feb 15, 2008
Dear All,
i'm trying to convert the datatype from ntext to nvarchar.i'm getting error. is it not possible?
Vinod
Even you learn 1%, Learn it with 100% confidence.
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May 24, 2006
I just move our SQL server to version 2005. In new version ntext field is deprecated and documentation says that ntext(max) should be used.
If I have table Table1 and ntext column Column1. When I execute following SQL statements:
alter table Table1 alter column
Column1 nvarchar(max)
go
1.) Are out of row data automatically move to in row?
2.) Or should I also execute something like this ?
update Table1 set Column1 = Column1+'' where Column1 is not null
3.) Is there way to check if data is stored out or in row?
Best regards
edvin
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Feb 19, 2008
Hi,
my question concerns both desktop and device apps.
I'm using sql compact to store some data. I often have to store strings (descriptions, url, etc.) but I don't know when to use nvarchar or ntext.
Nvarchar needs to have a size limit, but I often set it to 8092 when I don't know the actual limit (urls can be very long !).
I fear Ntext because I suppose there is performances impact.
Is there any "rules" to help to choose which data type I'd use ?
Thanks,
Steve
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Jan 22, 2005
I need to sort by an ntext field, but it won't let me do it.
However, if I cast the field as nvarchar(100), I can use ORDER BY on that.
Is there any reason that this is a bad idea? In my testing, ordering by a converted ntext field was actually *faster* than ordering by an nvarchar (same data in the fields).
Josh
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Apr 10, 2008
When I tried to insert armenian by doing the following
insert into tablex (field1) values (N'testdata')
it does not display in query analyzer or in the database as armenian.
When I copy this to word it does not convert it.
What else am I supposed to do to get that information to redisplay the correct way and I would appreciate any tutorials or samples you can show or direct me to.
Howard
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Oct 19, 2006
I have a live SQL 2005 database that has ntext fields, when the ntext fields go over 4000 chars the record can no longer be edited. It throws a string or binary data would be truncated error. I tried turning text in row OFF, but it did not work. Can anyone forsee any problems with changing the ntext fields to nvarchar(max) in the live database? Also, I came across sp_tableoption N'MyTable', 'large value types out of row', 'ON', does this work for ntext also? sp_tableoption N'MyTable', 'text in row', 'OFF' did not do anything.Any help would be appreciated.
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Apr 4, 2007
Like in the subject: What are the cons and pros of using nvarchar(max) versus ntext?
Does it have something to do with having to enable full text search perhaps in the latter case?
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Jul 23, 2005
Hi all,I need to store data into about 104 columns. This is problematic with MSSQL, since it doesn't support rows over 8kb in total size.Most of the columns are of type NVARCHAR(255), which means we can't havemore than 8092/(255*2) = 15 columns of this type.With a row length of more than 8kb, SQL gives a warning that any rows overthat amount will be truncated.So far I'm seeing two possible solutions to this problem:1. Split data into multiple tables with the same ID column accross alltables, and then join them on SELECT statements.2. Use NTEXT instead of NVARCHAR. NTEXT's length is 16 bytes because itcontains a pointer to the actual value stored somewhere else. However, NTEXTdoesn't support regular indexing, only through a Full-Text Index catalog. Inthis case I'll need to user "WHERE CONTAINS(columnName, 'sometext')" toperform searches, which is bearable.I'm inclined toward #2. However I haven't used Full-Text indices before anddon't know their limitations. Will I run into problems with NTEXT? Is therea better solution?Thanks.-Oleg.
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Oct 2, 2007
I hope this is the right forum for this question, my apologies in advance if it isn't....
We have a web based CGI product (written in C++ VS 6) that uses ODBC and takes text from a submitted web page and stores it in a SQL Server table in a field of type "ntext". The user in question is copying and pasting this text from an MS Word 2003 document. After the initial save our app errors out trying to access the table it just wrote to, and when we look in the table we see that up to **200 carriage returns** have been mysteriously inserted into the ntext field!! (Our product has been out in the field with no such problem for several years, so we are thinking it's related to something specific the customer is doing - perhaps with using MS Word for the source text.) We have tried but cannot duplicate the problem, but the customer sees it with each attempt to modify the table in question. The only thing that I see out of the ordinary is that the field in question is of type "ntext" - which supports unicode, instead of nvarchar. Does any of this ring a bell for anybody? I'm thinking of changing the field type to nvarchar to see if that solves the problem.
Thanks, Steve Bradbery
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Dec 14, 2004
I want to retrieve data from SQL containing non English character but fail, can anyone shed me some light?
What I use currently:
Dim strSQL As String
strSQL = "SELECT ArticleID, "
strSQL &= "ISNULL(Body, '') AS Body, "
strSQL &= "ISNULL(Subject, '') AS Subject "
strSQL &= "FROM Articles "
strSQL &= "WHERE (Subject LIKE N'%' + @Keyword + '%' OR [Body] LIKE N'%' + @Keyword + '%') "
Dim con As New SqlConnection(ConfigurationSettings.AppSettings("ConnectionString"))
Dim cmd As New SqlDataAdapter(strSQL, con)
cmd.SelectCommand.Parameters.Add("@Keyword", SqlDbType.NVarChar).Value = keyword
...
I'm not so sure where should I place the letter "N", I use :
SELECT ArticleID,
ISNULL(Body, '') AS Body,
ISNULL(Subject, '') AS Subject,
FROM Articles
WHERE (Subject LIKE N'%SomeNonEnglishString%' OR [Body] LIKE N'%SomeNonEnglishString%')
in Query Analzyer, it works! But it failed in my program... oh my god...
Thanks a lot!
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Jan 28, 2005
Hi,
We are in process of converting all of the data type of the fields from CHAR/VARCHAR/TEXT into NCHAR/NVARCHAR/NTEXT (DBCS). Having more than 900 store procedure its look like real pain to make modification in all of the SPs.
After failed to find any help from GOOGLE, I am posting this request. I am basically looking for any automated tool which are convert data type in SP based on the field of the table used in the SP. Or at least which can provide me some sort of list which can helpful for doing manual reactoring.
PLEASE HELP ME!!!
Thanks,
Firoz Ansari
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Mar 8, 2004
Hi,
We have a poorly performing SQL 2000 db. i have just defragged ( the HD, not indexes, these are done daily via SQL Agent) the data files of our server and have not found any improvement in response.
I have now got into using SQL profiler to analyse the server performance. in the results that the trace is returning there are some huge (REALLY BIG) values for the duration and cpu values but these rows have no textdata value returned (ie it is null)
why is this? for these rows, the reads and writes columns are also high.
if these rows are what is taking the cpu's time then how can i identify what the server is doing to make any changes?
any thoughts on what other values i might trace or what action i can take to find the slow down cause?
in performance manager the processors (dual Xeons) are rarely dropping below 60%.
thanks in advance
fatherjack
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Mar 13, 2007
Dear Experts,
I'm a DBA, Working for a Product based company.
We are implementing our product for a certain client of huge OLTP.
our reports team is facing problem (error: all the reports are timed out).though the queries are written properly, Each query is taking some minutes of time.
I've given the command DBCC DROPCLEANBUFFERS.
the time immediately dropped to 10 sec.
now my question is :
please suggest me the DBCC commands or any DBA related commands to improve the performance of the application for my reports team.
Thanks in advance.
Vinod
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Jan 15, 2008
Hi All,
from your experience in SQL 2005 - do i have any free software that can help in improve performance or can help in identifying performance bottleneck. two examples of performance and help that i use usually use are the maintenance plan that do (check DB > reorganized index > rebuild index > update statics) and the second software is the SQL 2005 DASHBOARD for the reporting help.
do you have any other free tools and help that you can give me for performance or any thing that i must have in my SQL 2005 servers.
Thx
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Jul 20, 2005
I have a table called work_order which has over 1 million records and acontractor table which has over 3000 records.When i run this query ,it takes long time since its grouping bycontractor and doing multiple sub SELECTs.is there any way to improve performance of this query ??-------------------------------------------------SELECT ckey,cnam,t1.contractor_id,count(*) as tcnt,(SELECT count(*) FROM work_order t2 WHEREt1.contractor_id=t2.contractor_id and rrstm=1 and rcdt is NULL) as r1,(SELECT count(*) FROM work_order t3 WHEREt1.contractor_id=t3.contractor_id and rrstm=2 and rcdt is NULL) as r2,(SELECT count(*) FROM work_order t4 WHEREt1.contractor_id=t4.contractor_id and rrstm=3 and rcdt is NULL) as r3,SELECT count(*) FROM work_order t5 WHEREt1.contractor_id=t5.contractor_id and rrstm=4 and rcdt is NULL) as r4,(SELECT count(*) FROM work_order t6 WHEREt1.contractor_id=t6.contractor_id and rrstm=5 and rcdt is NULL) as r5,(SELECT count(*) FROM work_order t7 WHEREt1.contractor_id=t7.contractor_id and rrstm=6 and rcdt is NULL) as r6,SELECT count(*) FROM work_order t8 WHEREt1.contractor_id=t8.contractor_id and rcdt is NULL) as open_count,(SELECT count(*) FROM work_order t9 WHEREt1.contractor_id=t9.contractor_id and vendor_rec is not NULL) asAck_count,(SELECT count(*) FROM work_order t10 WHEREt1.contractor_id=t10.contractor_id and (rtyp is NULL or rtyp<>'R') andrcdt is NULL) as open_norwoFROM work_order t1,contractor WHEREt1.contractor_id=contractor.contractor_id andcontractor.tms_user_id is not NULL GROUP BYckey,cnam,t1.contractor_id ORDER BY cnam*** Sent via Developersdex http://www.developersdex.com ***Don't just participate in USENET...get rewarded for it!
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Jul 20, 2005
Hey guys,Here's my situation:I have a table called lets say 'Tree', as illustred bellow:Tree====TreeId (integer)(identity) not nullL1(integer)L2(integer)L3(integer)....L10(integer)The combination of the values of L1 thru L10 is called a "Path" , andL1 thru L10 values are stored in a second table lets say called'Leaf':Leaf====LeafId (integer)(identity) not nullLeatText varchar(2000)Here's my problem:I need to lookup for a given keyword in each path of the tree table,and return each individual column for the paths that match thecriteria. Here's the main idea of how I have this now.SELECT TreeId,L1,L2,...,L10, GetText(L1) + GetText(L2) as L2text + ...+ GetText(L10) AS PathTextINTO #tmp FROM Tree //GetText is a lookup function for the Leaf tableSELECT L1,GetText(L1),L2,GetText(L2),...,L10,GetText(L10) FROM #tmpWHERECharIndex(@keyword,a.pathtext) > 0Does anyone would know a better,smart, more efficient way toaccomplish this task? :)Thks,
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Dec 14, 2007
SQL Experts,
I'm facing a performance issue with the following query...
The Output of the following Query is 184 Records and it takes 2 to 3 secs to execute the query.
SELECT DISTINCT Column1 FROM Table1 (NOLOCK) WHERE Column1 NOT IN
(SELECT T1.Column1 FROM Table1 T1(NOLOCK) JOIN Table2 T2 (NOLOCK)
ON T2.Column2 = T1.Column2 WHERE T2.Column3= <Value>)
Data Info.
No of records in Table1 --> 1377366
No. of distinct records of Column1 in Table1 --> 33240
Is there any way the above query can be rewritten to improve the performance, which should take less than 1 sec...
(I'm using DISTINCT because there are Duplicate records of Column1 inTable1 )
Any of your help in this regard will be greately appreciated.
--
ash
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Nov 5, 2007
I am not an expert in either SSIS or VFP technology but know enough to get my way round. One anomaly I did discover I thought was worth sharing for all those concerned with getting large amounts of data out of VFP in as short a time as possible. When you search for performance tips in relation to SSIS the advice is to never use select table or view from data access mode list in ole db source as this effectively translates to select * from table and I've never come across anything to contradict this €“ well I am and let me explain why:
When you use SQL command as data access mode in ole db source (where ole db source is foxpro dbc) and you write out select column1, column 2 etc etc from table a etc etc and then connect that to a destination (in my case ole db destination) the SSIS task spends ages stuck on Pre-execute before anything happens (the bigger the fox tbl the longer the wait). What is happening behind scenes is that the foxpro engine (assuming its foxpro engine and not sql engine €“ either way don€™t think it matters too much) is executing the sql command and then writing results to a tmp (temp) file on your local temp folder €“ (in my case : C:Documents and SettingsautologinLocal SettingsTemp1). These files take up gigs of space and it is only when this process is complete does the SSIS task actually finish the Pre-execute and start the data transfer process. I couldn€™t understand a) why my packages were stuck on pre-execute for such long times? and b) why were the tmp files being created and why they were soo big?
If you change from SQL command in source to Table or view and then select your table from list the SSIS task when executed kicks off immediately and doesn€™t get stuck on pre-execute nor create any tmp files €“ so you save time and disk space. The difference in time is immense and if like me you were really frustrated with poor performance when extracting from VFP now you know why.
Btw maybe this does not apply to all versions of VFP but it certainly does to v7.
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Jan 2, 2008
Hi,
I have database D1 which contains 5 million users and one more database D2 having 95k Users.
i wanted to insert common users into new database D3 based on filter which is Phone number and is unique value. Below is the structure of my tables in D1 and D2:
D1(database)
UserProfiles(Table)
UserId (Column Name)
UserProfiledata (Column Name)
D2 (database)
Alerts (Table)
PhoneNumbers (ColumnName - Unique)
Now userProfiles table contains data in string format as below:
User.state AA User.City CC User.Pin 1234 User.phonenumber 987654
so iam parsing for each user using cursor and writing phone numbers into some temp table and wanted to query D2 database to verify whether this phone number exists in Alerts Table of D2 database.
can anyone please suggest on how i can go ahead with this and also help me on how to improve perfomance.
Thanks,
-Veera
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Aug 15, 2006
Hi everyone
I need a solution for this query. It is working fine for 2 tables but when there are 1000's of records in each table and query has more than 2 tables. The process never ends.
Here is the query
(select siqPid= 1007, t1.Gmt909Time as GmtTime,(t1.engValue+t2.engValue+t3.engValue+t4.engValue) as EngValue,
t1.Loc1Time as locTime,t1.msgId
into #temp5
from #temp1 as t1,#temp2 as t2,#temp3 as t3,#temp4 as t4
where t1.Loc1Time = t2.Loc1Time and t2.Loc1Time = t3.Loc1Time and t3.Loc1Time = t4.Loc1Time)
I was trying to do something with this query.
But the engValues cant be summed up. and if I add that in the query, the query isnt compiling.
(select siqPid= 1007, t1.Gmt909Time as GmtTime,
t1.Loc1Time as locTime,t1.msgId,(t1.engValue+t2.engValue+t3.engValue+t4.engValue) as engValue
--into #temp5
from #temp1 as t1
where exists
(Select 1
from #temp2 as t2
where t1.Loc1Time = t2.Loc1Time and
exists
(Select 1
from #temp3 as t3
where t2.Loc1Time = t3.Loc1Time and
exists
(Select 1
from #temp4 as t4
where t3.Loc1Time = t4.Loc1Time))))
I need immediate help on that, I would appreciate an input on it.
Thanks
-Sarah
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Oct 20, 2002
I should add an Identity field (Identity=True) and a row version field(timestamp) to my table, and avoid to arrange tables into different databases, is it true in general?
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Jun 9, 2004
I have a view which uses UNION of two tables. First table has a 1.5 Million records and the second one has 40,000 records. When I query the view with a column (that is indexed in both tables) in the where clause, it's taking taking 3 Minutes to give the result. The column is of DateTime data Type. Any ideas as to how to improve the query performance ???
TIA
-XLDB
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Feb 28, 2005
Hello,
I have the following setup and I would appreciate any help in improving
the performance of the query.
BigTable:
Column1 (indexed)
Column2 (indexed)
Column3 (no index)
Column4 (no index)
select
[time] =
CASE
when BT.Column3 = 'value1' then DateAdd(...)
when BT.Column3 in ('value2', 'value3') then DateAdd(...)
END,
Duration =
CASE
when BT.Column3 = 'value1' then DateDiff(...)
when BT.Column3 in ('value2', 'value3') then DateDiff(ss,
BT.OrigTime, (select TOP 1 X.OrigTime from BigTable X where X.Column1 >
BT.Column1 and X.Column3 <> 'value4' order by X.Column1 ))
END,
FROM
BigTable BT where BT.Column3 = 'value1' OR (BT.Column3 in ('value2',
'value3') and BT.Column4 <> (select X.Column4 from BigTable X where
X.Column1 = BT.Column1 and X.Column3 = 'Value1'))
Apart from the above mentioned, there are a few more columns which are
just a part of select statement and are not in any condition statments.
The BigTable has around 1 Mil records and the response time is very
poor, it takes around 3 mins to retrieve the records (which would be
around 500K)
With the Statistics ON,
I get the following:
Table 'BigTable'. Scan count 2, logical reads 44184, physical reads 0,
read-ahead reads 0.
Table 'WorkTable'. Scan count 541221, logical reads 4873218, physical
reads 0, read-ahead reads 0.
Is there any way to increase the performance, so that I can get the
result under 1 minute?
Any help would be appreciated.
P.S: I tried indexing the Column3, but no improvement.
-SR
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Dec 4, 2006
I have this queston that I cannot get a clear answer on. I have searched the internet to find out if using foreign keys have any performane benefits but some articles yes and some say no. So what should I believe here. Does foreign keys have any performance benefits.
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Feb 13, 2014
i have column in table which contains tabs and " i want replace with space...i am using repalce function is thier other way to improve performance with out using replace function.
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Jan 19, 2008
Dear All,
i've tried with indexed views, but because the view is referenceing another view, i was unable to create a clustered index on that view.
so please let me know how can i improve the performance of the view.
thank you very much
Vinod
Even you learn 1%, Learn it with 100% confidence.
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Jul 23, 2005
Hello,I have the following setup and I would appreciate any help in improvingthe performance of the query.BigTable:Column1 (indexed)Column2 (indexed)Column3 (no index)Column4 (no index)select[time] =CASEwhen BT.Column3 = 'value1' then DateAdd(...)when BT.Column3 in ('value2', 'value3') then DateAdd(...)END,Duration =CASEwhen BT.Column3 = 'value1' then DateDiff(...)when BT.Column3 in ('value2', 'value3') then DateDiff(ss,BT.OrigTime, (select TOP 1 X.OrigTime from BigTable X where X.Column1 >BT.Column1 and X.Column3 <> 'value4' order by X.Column1 ))END,FROMBigTable BT where BT.Column3 = 'value1' OR (BT.Column3 in ('value2','value3') and BT.Column4 <> (select X.Column4 from BigTable X whereX.Column1 = BT.Column1 and X.Column3 = 'Value1'))Apart from the above mentioned, there are a few more columns which arejust a part of select statement and are not in any condition statments.The BigTable has around 1 Mil records and the response time is verypoor, it takes around 3 mins to retrieve the records (which would bearound 500K)With the Statistics ON,I get the following:Table 'BigTable'. Scan count 2, logical reads 44184, physical reads 0,read-ahead reads 0.Table 'WorkTable'. Scan count 541221, logical reads 4873218, physicalreads 0, read-ahead reads 0.Is there any way to increase the performance, so that I can get theresult under 1 minute?Any help would be appreciated.P.S: I tried indexing the Column3, but no improvement.
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May 18, 2006
I am developing reporting service and using lots of 'LEFT OUTER JOIN',I am worried about the performance and want to use some subquery toimprovethe performance.Could I do that like below,[the origin source]SELECT *FROM TableALEFT OUTER JOIN TableBON TableA.item1 = TableB.item1WHERE TableA.item2 = 'xxxx'TableB.item2 > yyyy AND TableB.item2 < zzzzI add the subquery to query every table before 'LEFT JOIN'--------------------------------------------------------------------------SELECT *FROM(SELECT *FROM TableAWHERE TableA.item2 = 'xxxx') TableCLEFT OUTER JOIN(SELECT *FROM TableBWHERE TableB.item2 > yyyy AND TableB.item2 < zzzz) TableDON TableC.item1 = TableD.item1WHERE TableC.item2 = 'xxxx'TableD.item2 > yyyy AND TableD.item2 < zzzz--------------------------------------------------------------------------Can anyone give me some suggestion?Thanks a lot.Leland Huang
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Jul 20, 2005
Hi All,I am getting slower performance of select statements in MS SQL. I amfinding select statements in MS SQL are even slower than MS ACCESS. Isthere any way to improve the performance of select statements in MSSQL by tuning the database of anything else??Thanks in advance!Hoque
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