How To Guarantee Unique Of Columns &&> 900 Bytes
Aug 14, 2006
We have an app that threads together emails coming out of Exchange, using their messageid. To ensure threading works correctly, we need to ensure uniqueness of messageid, which we do with a unique index (we also need to be able to lookup by messageid when a message comes in).
We are currently porting the app from Oracle and PostgreSQL to SQL Server and are having problems with the 900 byte max length of an index. The problem is that the maximum size of a messageid (according to the Exchange docs) is 1877 bytes.
How can we guarantee uniqueness?
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Apr 22, 2015
following table global_usage
ID varchar (contains alphanumeric values,not unique)
Territory (combined with ID unique)
Total_Used int can be null
Date_ date (date of the import of the data)
ID Territory Total_Used Date_
ACASC CAL071287 2014-06-01
ACASC CAL071287 2014-08-01
ACASC CAL071288 2014-09-01
[Code] .....
Now the problem,per month I need the most recent value so I'm expecting
ACASC CAL071287 2014-06-01
ACASC CAL071287 2014-08-01
ACASC CAL071288 2014-09-01
ACASC CAL071288 2014-11-01
ACASC CAL071190 2014-12-14
ACASC CAL071286 2015-01-22
ACASC CAL071165 2015-02-01
ACASC CAL071164 2015-03-01
I've tried a few thing like group,having even row_number() but I keep getting wrong results
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Apr 23, 2008
Hi,
I€™m trying to create a VERY wide table, with 1,000 columns of type varchar(MAX), nullable.
The CREATE TABLE statement (both in SQL 2005 & 2008), gives the following warning:
Warning: The table "WIDE_TABLE" has been created, but its maximum row size exceeds the allowed maximum of 8060 bytes. INSERT or UPDATE to this table will fail if the resulting row exceeds the size limit.
When I insert data into the table, filling all columns with small, 10-byte string values, I get the following error:
Msg 50000, Level 16, State 1, Procedure sp_pivot, Line 118
Cannot create a row of size 15034 which is greater than the allowable maximum of 8060.
I€™d like to verify this observation: each row is created with 2000 bytes of offset data (2 byte * 1000 columns), 125 bytes for null bitmap (1000 columns / 8 bits) and some more €œwasted€? row information. This leaves less than 6K for the data itself. But since not all columns can fit within the page, forwarding pointers in the row need to be created, 24 byte per column, which very quickly add up to more than 8K, thus the error. So the 8K limit is met for much less columns than the max 1024 column restriction.
Furthermore, in SQL 2008, SPARSE columns will not solve the problem (maybe save some €œmetadata€? space in case the columns are null, but if not, I€™m with the same problem again, or even worse, since now each value takes more storage space. The max 30,000 columns in 2008 is only for cases where the column values are really sparse€¦
Is this the right observation? if so, is there a workaround besides splitting to multiple tables?
Thanks,
Aviv.
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May 10, 2006
I need to run a few short-running queries against a production system. I need to be absolutely certain that SS doesn't take out any locks on the table as a result.
Does "with (nolock)" absolutely guarantee this? I've read BOL on the topic and I understand isolation level read-uncommitted. But I want to validate that there's not any undocumented behavior in SS that might violate the documentation (which clearly states that no shared locks are issued).
Thanks!
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Sep 17, 2007
Hi -
In my application, I need to be able to guarantee that processing for a re-used conversation is completed prior to starting processing the next (re-used) conversation. My application is based on the concepts from the sample posted on Remus's blog: http://blogs.msdn.com/remusrusanu/archive/2007/05/02/recycling-conversations.aspx#comments). Essentially (in this sample), we create a new conversation for each SPID and re-use the conversation, so that messages are sent through the queue (and processed in order) for each SPID. SPID was used in the sample code as an example of some application-specific "thing" that you care about message ordering for. To prevent a conversation from living forever (using up log/resources), they are ended after 1 hour using DialogTimer and a customer message type.
My conundrum is this:
Assume conversation 1 (on SPID 1) is flooded with a large number of messages just before the conversation timer expires. The DialogTimer then expires before the target queue is drained. The sample code (mentioned above) then creates a new conversation for the same SPID (with a DialogTimer of 1 hour). Until the queue for conversation1 is drained, we have 2 conversations being processed for the same SPID. This same problem would occur in any application where you re-use conversations for a period of time (using DialogTimer), and then start a new conversation when the DialogTimer expires.
So although I like having the idea fof being able to re-use conversations, I would need to guarantee that conversation 1 is finished processing before conversation 2 starts processing (for the same SPID, to be consistent with the sample above). If I could get these 2 conversations into the same conversation group on the target queue, the CG locking would solve the problem. But because conversation groups only apply to the initiator queue (when you begin dialog with related conversation), I have no "out of the box" way to control how the conversation groups are associated on the target queue. Remus posted an idea here (bottom of thread): http://forums.microsoft.com/MSDN/ShowPost.aspx?PostID=182646&SiteID=1, which was to just send a special message at the beginning of each new conversation (containing the conversation group to use), and then doing a move conversation to conversationgroupid on the target queue. I've tried this solution, and the problem is 1.) if the set convo message fails for some reason, the conversation group is not set and 2.) if the target queue seems to reject most of my move conversation commands with the error "The destination conversation group '<conversation guid>' is invalid." - which I am guessing is due to the fact that this convo group id is being used on the initiator as well.
Any ideas?
Thanks!
Terryc
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Feb 21, 2008
Hi Guys, I came here again to ask something about my application, Is there a way to make 2 columns unique with each other even if they don't have a primary key? If there's a way how? I wanna make a rule so, my application wont replicate its record. Graciaz,Nhoyti
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Feb 13, 2004
I use the identity = yes for my unique columns in most of my tables that need it. I am trying to decide if I should change identity = no, and instead manually update my unique number column myself by adding one when I insert new rows.
The reason I want to do this is for maintainabilty and ease of transfering data for backup to other sql servers. I always have trouble keeping the identity numbers to stay the same as they are in the original database because when they are transfered to a db that has identity = yes, the numbers get rearranged.
It will also make it easier to transfer data from original db to another sql server db and use the data right away without having to configure the destination db to disable identity and then enable it, etc.
Any pro's con's appreciated,
Dan
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Mar 20, 2013
I have result set as the attached in screenshot, where the candidateid gets duplicated, but then the column university and careerchoice column has different values for the same candidate. (the CareerChoice and University comes from different tables and i have used union clause)
What want is e.g. CandidateId 186 repeats three times, it should be one row, with three columns all filled with the values which are in different rows.
So that I don't have duplicate candidate ids and i have single row with all column data.
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Apr 19, 2013
I find to be able to have multiple NULL entries in the following constraint:
Code:
CREATE UNIQUE INDEX my_uidx ON my_table(my_col1,my_col2) WHERE ??? IS NOT NULL;
But is not possible to check multiple columns in "WHERE".
I using SQL Server 2012 Express
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Mar 7, 2006
Hi i am designing a database. It will be used by field guys who will insert new records and will replicate at the end of the day with a central database using merge replication. Can anyone tell me if I am choosing wisely or not with the following 3 points:
1. i am going to use a uniqueidentifier value in a column (using newid()) for the merge replication. (I don't care that it's an ugly value as i never plan to look at it.
2. I am using an identity column (INT)to create a unique value within the table
3. I want to create a unique column comprising of data from other columns (e.g. date+identity+salesrep) This gives me an intelligent candidate for a primary key. But I think i have to create this with an instead of trigger (is that right)
many thanks in advance
ICW
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May 17, 2007
Using DISTINCT with SELECT have effect only for one column.
But when is needed to select (or to count) queries for all rows for all columns in a table without duplicates, doesn't work.
Select DISTINCT a1,a2,a3,a4 From Y ---> results 167 rows
Select DISTINCT a4 From Y ---> " 85 rows
Any thoughts?
Jorge3921
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Feb 12, 2006
Hello.
Could anyone tell me why it is not possible to create a foreign key on two columns those references on 2 columns in another table? Those 2 columns have each a unique constraint.
I have:
CREATE TABLE T_PK (ID1 INT CONSTRAINT CHK_UNIQUE1 UNIQUE,ID2 INT CONSTRAINT CHK_UNIQUE2 UNIQUE)
CREATE TABLE T_FK (ID1 INT, ID2 INT)
And I want to do:
ALTER TABLE T_FK ADD CONSTRAINT CHK_FK FOREIGN KEY (ID1, ID2) REFERENCES T_PK (ID1,ID2)
I see no reason why this is not working because always
a row in the table T_FK referencing only one row in table T_PK.
Thank you.
Have a nice day.
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Feb 23, 2006
my table :
CREATE TABLE [dbo].[users] (
[ID] [int] NOT NULL ,
[A1] [nvarchar] (100) NULL ,
[A2] [nvarchar] (100) NULL ,
[A3] [nvarchar] (100) NULL
) ON [PRIMARY]
i must keep ID columns as primary key
ALTER TABLE [dbo].[users] WITH NOCHECK ADD
CONSTRAINT [PK_users] PRIMARY KEY CLUSTERED
(
[ID]
) ON [PRIMARY]
but now A1+A2 must be unique
how can i do it ?
thank you
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May 15, 2008
hi guys,
i have 3 tables (T1, T2, T3), each with the same structure:
ID1 -> char(10)
ID2 -> char(12) NULL
ID3 -> char(10)
Value1 -> money
Value2 -> money
Value3 -> money
Note1 -> Text
Note2 -> Text
ID1+ID2+ID3 is the clusterd unique key in each table
what i want:
ID1, ID2, ID3 (with distinct occurencies of all 3 tables), T1.Value2, T2.Value2, T2.Value3, T3.Value1, T3.Note1
what i tried is to get all possible rows with
SELECT ID1,ID2,ID3 FROM T1
UNION
SELECT ID1,ID2,ID3 FROM T2
UNION
SELECT ID1,ID2,ID3 FROM T3
but i dont know how to join or add the other columns. maybe with
WITH RowList (ID1,ID2,ID3) AS ( ... code above.... ) SELECT ...
any ideas?
thx
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Oct 31, 2005
Can you create a unique constraint on multiple columns, or does it haveto be implemented as a unique index?If possible can someone please post some sample code?Thanks,
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Jul 20, 2005
Hi,I would like to add a unique index that consists of two fields in atable.e.g. tbl_A (field1,field2) -- field1 & field2 Indexed and combinationmust be Unique.Can anyone tell me the actual sql syntax to create this index?Thanks,June.
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Feb 9, 2007
Perhaps one too many 2000 DTS packages have permanently damaged my ability to think clearly - however, I've find myself very frustrated attempting to create a SSIS Data Flow which replaces a very simple 2000 DTS package.
Take data from table1 in database1, put it in table2 in database2. Table2 in Database2 has an additional column as part of the primary key - so I need to add an arbitrary unique value in each row as it's inserted. Previously, I did this in the transformation script through a variable I incremented.
What's the recommend method to do this now - since row level processing of variables seem to be a no-no?
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May 31, 2007
In tables where reporting or historical information needs to be maintained I find that logical deletion of rows is better than actually deleting the row and any FK relationships. However when one of the columns in the table must be unique this introduces a problem because uniqueness only matters for "active" rows. I'm hoping someone can provide some advice on how to best handle this situation.
Here is an example to work from. Suppose we have a table that contains job positions. The table contains an IDENTITY column for the PK (to avoid duplicating position names), a Name column that must be unique and an IsActive column that is set to 0 when the position has been "deleted". This setup allows for historical reporting to properly pick up the position information even though it might no longer be used in a company. You can substitute your own scenarios here as there are quite a few.
Now if the Name column is marked as a unique column then the DB will enforce integrity which is what we want. However we will want to be able to "delete" a position but later add a new position with the same name. One could argue that we should just "undelete" the original position but that is not often a good idea so assume "undelete" is not an option. Given the unique constraint a new position could not be created if an existing position (active or otherwise) already existed with the same name. We could set up the unique constraint to include the Name and IsActive columns but now we are prevented from ever deleting two positions with the same name.
My initial thought is to create a new UniqueName column that is unique and remove the uniqueness constraint on the Name column. The UniqueName column is set (via a trigger) to the Name column when the position is active. When the position is deleted the trigger changes the UniqueName to include a timestamp or something to ensure uniqueness. This is handled by the system and not exposed to clients.
Any advice or alternatives on this approach (preferably with advantages and disadvantages)? Thanks.
Michael Taylor - 5/31/07
http://p3net.mvps.org
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Mar 18, 2007
Hi there, im still learning SQL so thanks in advance.I have a table with columns of customer's information, [customerID], [customerFirst], [customerLast], , [program] ... other columns ... There will be entries where there can be duplicate customerFirst and customerLast names. I would like to just return a single entry of the duplicate names and all associated row information. IE: [customerID], [customerFirst], [customerLast], [ email], [program] 01 Bill Smith bill.smith@hotmail.com ymca 02 Bill Smith bill.smith@hotmail.com Sports 03 jon doe jon.doe@hotmail.com AAA 04 jon doe jon.doe@hotmail.com Ebay 05 Paul Sprite paul.sprite@hotmail.com Rec Desired Returned result: 01 Bill Smith bill.smith@hotmail.com ymca 03 jon doe jon.doe@hotmail.com AAA
05 Paul Sprite paul.sprite@hotmail.com Rec So in my code i have this:dAdapter = new SqlDataAdapter("SELECT * FROM [Poc_" + suffix + "] WHERE (SELECT DISTINCT [CustomerLastName], [CustomerFirstName], [CustomerEmail] FROM [Poc_" + suffix + "])", cnStr); dAdapter.Fill(pocDS, "Data Set"); However this is throwing up an error when i build the app: An expression of non-boolean type specified in a context where a condition is expected, near ')'.
Description: An
unhandled exception occurred during the execution of the current web
request. Please review the stack trace for more information about the
error and where it originated in the code.
Exception Details: System.Data.SqlClient.SqlException:
An expression of non-boolean type specified in a context where a
condition is expected, near ')'.
Source Error:
Line 52: //dAdapter = new SqlDataAdapter("SELECT DISTINCT * FROM [Poc_" + suffix + "] ORDER BY [CustomerLastName]", cnStr); Line 53: dAdapter = new SqlDataAdapter("SELECT * FROM [Poc_" + suffix + "] WHERE (SELECT DISTINCT [CustomerLastName], [CustomerFirstName], [CustomerEmail] FROM [Poc_" + suffix + "])", cnStr); Line 54: dAdapter.Fill(pocDS, "Data Set");Line 55: Line 56: //Dataset for name comparison 1: Can someone explain to me why this error is happening?2: Can soemone confirm that my intentions are correct with my code?3: If I'm completely off, can someone steer me in the right direction?Thanks alot!-Terry
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Jan 19, 2008
Hello, I will explain myself further. I want to make my table in such a way that no two colums have the same value for example:
Row 1 - Column 1 = "cool"
Row 1 - Column 3 = 91
Row 3 - Column 1 = "cool"
Row 3 - Column 3 = 91
I dont care about one column having duplicate values, I want to protect against Column 1 and 3 having the same values on other rows. Is this possible to do in sql server?
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Apr 3, 2000
I have 4 rows which are exactly the same. I want to delete one row but i do not have any unique identifing columns. How should i delete that row ?
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Dec 30, 2004
I try to search my data and sort the result by importance.
I'm using a MS Access database and my data (table1) looks like this:
Code:
ID NAME TEXT
1 Apples Good red apples
2 Bananas Fine yellow bananas
3 Yellow apples Great yellow apples
I want to search the data and get a result where the column "NAME" is more important than "TEXT". My SQL looks like this:
Code:
SELECT id,name,text,1 AS searchorder FROM table1 WHERE name LIKE '*yellow*'
UNION
SELECT id,name,text,2 AS searchorder FROM table1 WHERE text LIKE '*yellow*'
ORDER BY searchorder
The output is this:
Code:
ID NAME TEXT SEARCHORDER
3 Yellow apples Great yellow apples 1
2 Bananas Fine yellow bananas 2
3 Yellow apples Great yellow apples 2
So far so good - the order by importance works - but I do not get unique columns because of the searchorder column.
Can I fix my SQL so I get unique columns where the last line of "Yellow apples" does not appear or am I lost in space?
Best regards,
Peter from Denmark
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Jun 20, 2008
Hi Guys.
I have a problem. I have two feilds in a table. Both of them are (int). I want to be able make sure the same number is not put in both columns for each row. Both colums have to be a different number, and also if one is null, the other cannot be. How do I go about enforcing this policy?
For Example:
This is what I want
ID Column1 Column2
--- -------- ---------
1 5 8
2 5 7
3 null 10
4 6 2
This is what I DO NOT want:
ID Column1 Column2
--- -------- ---------
1 5 5
2 5 5
3 7 7
4 null null
I created a unique constraint between the 2 columns, but it still allows dups within the row. Please help me.
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May 5, 2008
I am trying to create a Unique Constraint on a SQL Server 2005 table where the uniqueness is based on 2 columns.
Could anybody provided some help on how I could enforce this on an existing table (link, or example) I have been looking around without luck.
Thanks in advance
John.
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Apr 18, 2014
write a query which retrieves only unique rows excluding some columns.
IdStatusmanager Team Comments Proj number Date
19391New XUnassigned One 3732.0 16-Apr-14
19392Can YCustomer Two 3732.0 17-Apr-14
19393Can YCustomer Two 3732.0 17-Apr-14
19394Can YCustomer One 3732.0 18-Apr-14
19395New YCustomer One 3732.0 19-Apr-14
19396New YCustomer One 3732.0 21-Apr-14
19397New ZCustomer One 3732.0 20-Apr-14
In the above table project number and id shouldn't be considered and I should get the unique rows considering rest of columns and sorted based on date. Expected result is
IdStatusmanager Team Comments Proj number Date
19391New XUnassigned One 3732.0 16-Apr-14
19392Can YCustomer Two 3732.0 17-Apr-14
19394Can YCustomer One 3732.0 18-Apr-14
19395New YCustomer One 3732.0 19-Apr-14
19397New ZCustomer One 3732.0 20-Apr-14
19396New YCustomer One 3732.0 21-Apr-14
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Sep 19, 2006
andre writes "I have two questions:
1.)How do i determine if fields are not unique??
2) How to update one table with values from another table when the row names are diffrent??
Thank you!!"
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Oct 19, 2015
I am trying to achieve the below problem statement, however I am getting stuck at the looping part.
EX: We have three columns
First Name |Â Last Name | Mothers Name
I want to generate the username field using above columns, so lets consider, I have following data
First Name |Â Last Name | Mothers Name
a                   b                 cdef
a                   b                 cdfg
a                   b                 cdfj
Expected Usernames:
1: a.b
2: a.b.c
3. a.b.cd
Basically, it has to be FirstName.LastName.(incremental letters from MothersName until the name becomes unique)
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May 11, 2015
I would like to know what is the use of business key? Is it necessary to have unique key between source and destination? If no, How can we implement SCD?
PS : My source is CSV files and Destination is Oracle DB?
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Sep 15, 2014
I am looking to create a script that will go through a table a pick out the necessary columns to create a unique record. Some of the tables that I am working with have 200 plus columns and I am not sure if I would have to list every column name in the script or if they could be dynamically referenced. I am working with a SQL server that has little next to no documentation and everytime I type to mere some tables, I get too many rows back.
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Oct 27, 2015
We are on SQL 2014...we have a bunch of views in a database where we are trying to find the views which have more than 16 columns max for unique index/constraint...this is needed so we can convert them to indexed views...
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Sep 16, 2015
In SQL 2012.A query that joins 2 table, with order by clause doesn't get sorted and the result set is not ordered. This happens when some of the columns in the where criteria are in a unique index which is the index that is used for the join between the 2 tables, and all the columns in the unique index are in the where criteria.In the query plan there is no component for sort.The work around was to drop the unique index, or change it to a non-unique index. Once this was done, the execution plan was changed to add the sort component (even when the index was changed to non-unique and the join was still using this index).
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Jul 5, 2015
This index is not unique
ix_report_history_creative_id
Msg 2601, Level 14, State 1, Procedure DFP_report_load, Line 161
Cannot insert duplicate key row in object 'dbo.DFP_Reports_History' with unique index 'ix_report_history_creative_id'.
The duplicate key value is (40736326382, 1, 2015-07-03, 67618862, 355324).
Msg 3621, Level 0, State 0, Procedure DFP_report_load, Line 161
The statement has been terminated.
Exception in Task: Cannot insert duplicate key row in object 'dbo.DFP_Reports_History' with unique index 'ix_report_history_creative_id'. The duplicate key value is (40736326382, 1, 2015-07-03, 67618862, 355324).
The statement has been terminated.
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Apr 25, 2001
SQL 7
One of my programmers brought an error to me that I need to get some clarification on ...
Its says:
The total row size (24301) for table xxxx eceeds the max number of bytes per row(8060). Rows that exceed the max number of bytes will not be added.
Thoughts ...
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