Junction/link Table Primary Key: Best Practice Using SQL Server
Nov 30, 2005
Hi all,
This is a bit of a general question regarding SQL Server link tables that i hope someone can find the time to answer.
I am looking for the best practice. If I have 3 tables
1) tblCompetition
2) tblTeams
3) tblTeamsInCompetition (this is the link table)
I know the link table should have a related CompetitionID and TeamID,
but should the link table also have a primary key that is an identity
autoincrement by 1 just as you would with the other two tables. In
Access I have never done this, however in SQL Server I have read that
you should do this (but now I can't find the documentation again which
prompts me to ask the question here).
Thanks for taking the time to answer this question.
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Jan 26, 2006
hi there,
i have the following joining table (many-to-many relationship)...
CREATE TABLE [dbo].[products_to_products_swatch] (
[products_to_products_swatch_id] [int] IDENTITY (1, 1) NOT FOR REPLICATION NOT NULL ,
[product_id] [int] NOT NULL ,
[products_swatch_id] [int] NOT NULL
) ON [PRIMARY]
GO
question: do i need to include a primary key in this table - being that it is a joing table?
thanks
mike
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Oct 10, 2007
Hello,
This seems like such a simple problem but I am new developer even through I have been on the administration end of things for some time. I will go into more detail about my tables and there relationships below. Anyway, I am trying to create a many-to-many relationship within ms sql server 2005. I have created both of my primary tables and also a junction table per the directions on microsoft's website all per ms's instructions as stated here...
http://msdn2.microsoft.com/en-us/library/ms178043.aspx
At then end of these instruction it states as a NOTE: The creation of a junction table in a database diagram does not insert data from the related tables into the junction table. For information about inserting data into a table, see How to: Create Insert Results Queries (Visual Database Tools).
http://msdn2.microsoft.com/en-us/library/ms189098.aspx
and these directions do not go into detail on how to do an insert on a junction table. And I cant find out how to do this anywhere on the internet... I did create a T-SQL INSERT statement in a trigger as listed below but I end up getting an error AS LISTED BELOW....
Here is how I set everything up...
PetitionSet table consists of:
PetitionSetID int auto-increment primary key
PetitionSetName varchar(50) no nulls
PetitionSetScope varchar(50) no nulls
the Petition table consists of:
PetitionID int auto-increment primary key
PetitionSetID int no nulls
PetitionName varchar(50) no nulls
the SetToPetitionJunction table consists of:
PetitionSetID int
PetitionID int
And, there is a composite key made up of both the PetitionSetID and PetitionID fields.
I have created the foreign key relationships with DEFAULT VALUES from the SetToPetitionJunction table to each column's respective corresponding column in each of the tables: PetitionSet and Petition.
The trigger is on the Petition table and it has the following code:
set ANSI_NULLS ON
set QUOTED_IDENTIFIER ON
go
-- =============================================
-- Author: Name
-- Create date:
-- Description:
-- =============================================
ALTER TRIGGER .[SetToPetitionJunctionTrigger]
ON .[dbo].[Petition]
AFTER INSERT
AS
BEGIN
-- SET NOCOUNT ON added to prevent extra result sets from
-- interfering with SELECT statements.
SET NOCOUNT ON;
INSERT INTO SetToPetitionJunction
(PetitionID, PetitionSetID)
SELECT Petition.PetitionID, PetitionSet.PetitionSetID
FROM Petition INNER JOIN
PetitionSet ON Petition.PetitionSetID = PetitionSet.PetitionSetID
END
I have created an asp.net 2.0 front end to insert values into the PetitionSet table and the Petition Table. And in the detailsview for the Petition table I manually insert the PetitionSetID field to the number that corresponds to an auto-generated number on the primary key of the PetitionSet table. So I am maintaining referential integrity...
The first time it works and inserts one record in the Junction table containing the PetitionSetID from the PetitionSet table and the PetitionID from the petition table.
Then when I try to add in another petition for the same petition set number just like I did the first time and then I get this error...
Violation of PRIMARY KEY constraint 'PK_SetToPetitionJunction'. Cannot insert duplicate key in object 'dbo.SetToPetitionJunction'.
The statement has been terminated.
David
All Rights Reserved in All Media
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May 13, 2006
I've searched the posts and library. Associates have different ideas on the topic. So what is your opinion?
For SQL 2005, what is the recommended data type for a primary key?
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Feb 17, 2006
I have two tables. A table called users (content speaks by it self) and a table called groups.
Since i want every user to be able to be a member of several groups and, of course, a group to have several users i have made a junction table called jt.
The junction table contains userId's and groupId's according to the user-group bindings. The primary key(identity) in the junction table is a int named jtId.
Now i want to take out all posts from the junctiontable and the corrresponding userName (s) from the users-table and the corresponding groupName from the groups-table.
Can somebody please help me to make a SQL command that will di that for me. I have tried with INNER JOIN and several SELECTS in the same command.
Thanks in advance, Greetings from Esben
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May 9, 2007
I am trying to update 2 tables at the same time by adding new records to them and then making sure that they are related on my junction table?
Table1
packageID
Packagename
Table2 (JunctionTable)
PackageID
JobID
Table3
JobID
JobName
And I want to create a new package and new Job Name at the same time I would need to make multiple insert statements
First take care of the new Package
INSERT INTO Table1 (PackageName) Value (@PackageName)
Then Take Care of the JobName
INSERT INTO Table3 (JobName) Value (@JobName)
Finally marry the two together
but how?
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Nov 7, 2007
This is for SQL2k5. The database may be small or big, I don't know (it's going out to multiple customers). I'm wondering if in general it's considered "better" to create a single non-primary default filegroup and put all the objects there, or just leave everything in primary? In one training years back I got the impression that recovering the primary filegroup was important for certain restore operations, so it was always wise to separate them like this.
Thanks for your input,
Mike
MCDBA
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Sep 23, 2007
Looking for some help here, so thanks for any input. I'm a painfully new newbie to SQL scripting.Situation:
I have a simple database to handle an organization's events. Those
events are categorized and may have more than one category assigned to
each event. I need a maintenance Web Form to update their events.Set
Up (so far): I have a CATEGORIES table. It has an auto incrementing UID
and a Category name field. This table will be updated so infrequently,
I plan to update it manually (no need for a maintenance Web Form). Next
is the EVENTS table. It also has an auto incrementing UID along with
several fields (Title, Location, DateTime, etc.). The junction table is
named jEVENTSCATEGORIES. It has its own auto incrementing UID along
with 2 fields named for the primary keys (UIDs) in the other 2 tables
(EventsID and CategoryID).Goal: On the Web Form, I have a
CheckBoxList control that's populated by the CATEGORIES table. One or
more categories can be checked for each event. I have a FormView
control that allows Edits and Inserts.Need: I need to know the
INSERT statement(s) required to insert a new record in the EVENTS table
and then to update one or more rows in the junction table
(jEVENTSCATEGORIES).My Assumptions: I know how to create
SELECTs and INSERTs and whatnot, but I'm not certain how to create a
second INSERT statement that is based on a variable (or output) from a
previous action. So any help would be MUCH appreciated. Thanks for your
time!
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Jan 30, 2008
Hi i have a junction table(UserGroups) which is linking my users table with my groups table, however when the information is coming back in the format below, instead i want the group names to appear in only one field, instead of repeating the same data, could someone please tell me what i need to change
UserName: Edwin CarolsUserAge: 28JobTitle: ManagerGroupName: MUFC
UserName: Edwin CarolsUserAge: 28JobTitle: ManagerGroupName: AFC
Below is my SQL statement;
SELECT Users.UserName,Users.UserAge, Users.JobTitle, Groups.GroupName FROM Users INNER JOIN UserGroups ON Users.UserID = UserGroups.UserID INNER JOIN Groups ON UserGroups.GroupID = Groups.GroupID WHERE (Users.UserID = '5')
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May 5, 2014
Why do we need a junction table in a many to many relationship? Why can't everything be in just 2 tables?
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Jul 20, 2005
As an example, I am building an authentication mechanisim that will usedata in the 3 left tables to determine rights to objects in adestination table, diagrammed below. In this structure, multiplerecords in the left tables will point to multiple records in the righttable. Normally, I would approach this problem using junction tables(LeftID, RightID) to create many-to-many joins.However, given the structure of each table is nearly identical (as faras the linking IDs are concerned), I could also use a single junctiontable with columns for each available table ID (LeftID1, LeftID2,LeftID3, RightID). In this table, only two IDs would be utilized perrow (LeftIDx -> RightID).In both designs, the needed rights information is returned from fairlysimple views, thus the end result is equivalent. The advantage to thesecond, multi-ID junction table design, is a simpler databasestructure. However, never using this approach before, I am unsure ofthe potential future performance impacts.Any significant downsides to this second design? Examples of anabbreviated structure follow:Data Tables-----------LeftTable1LeftID1 (int)Data1LeftTable2LeftID2 (int)Data2LeftTable3LeftID3 (int)Data3DestinationTableRightID (int)DataLinking tables option 1-----------------------JunctionTable1LeftID1RightIDJunctionTable2LeftID3RightIDJunctionTable3LeftID3RightIDLinking table option 2----------------------JunctionID1 (int)ID2 (int)ID3 (int)DestinationID (int)
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Feb 28, 2008
Hi i have a junction table(UserGroups) which is linking my "users" table with my "groups" table, however when the information is coming back in the format below, instead i want the group names to appear in only one field, instead of repeating the same data, could someone please tell me what i need to change.
UserName: Edwin CarolsUserAge: 28JobTitle: ManagerGroupName: MUFC
UserName: Edwin CarolsUserAge: 28JobTitle: ManagerGroupName: AFC
Below is my SQL statement;
SELECT Users.UserName,Users.UserAge, Users.JobTitle, Groups.GroupName FROM Users INNER JOIN UserGroups ON Users.UserID = UserGroups.UserID INNER JOIN Groups ON UserGroups.GroupID = Groups.GroupID WHERE (Users.UserID = '5')
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Mar 1, 2008
Hi i have a junction table(UserGroups) which is linking my "users" table with my "groups" table, however when the information is coming back in the format below, instead i want the group names to appear in only one field, instead of repeating the same data, could someone please tell me what i need to change.
UserName: Edwin Carols
UserAge: 28
JobTitle: Manager
GroupName: MUFC
UserName: Edwin Carols
UserAge: 28
JobTitle: Manager
GroupName: AFC
Below is my SQL statement;
Code:
SELECT Users.UserName,Users.UserAge, Users.JobTitle, Groups.GroupName FROM Users INNER JOIN UserGroups ON Users.UserID = UserGroups.UserID INNER JOIN Groups ON UserGroups.GroupID = Groups.GroupID WHERE (Users.UserID = '5')
And my table structure is like;
Users; UserID, UserName, UserAge
Groups; GroupID, GroupName
UserGroups; UserGroupID, UserID, GroupID
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Feb 3, 2006
When trying to link to an SQL table in Access 2003, the software appears to be malfunctioning.
The sequence of events is File - Get External Data - Link Tables - Files of Type: ODBC Databases().
The Problem: On two of my computers, the select data source window does not pop up, preventing me from linking to any ODBC data source.
Observations: This function has worked normally in the recent past and works on other computers running Access 2003. One difference between the computers working and non-working computers is Norton Antivirus 2006 (recent upgrade).
Has anyone experienced anything like this? What's going on?
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May 1, 2008
Hello specialists.
Maybe this is the wrong formum but I've got a question for which you probably have the answer, i hope.
Situation
------------
John is member of Group_A and Group_B
Bill is member of Group_B and Group_C
Allison is member of Group_A and Group_E
How can I create a query to input Allisons username into table 1 and groupmembership into table 2. Also updating the relationship within junction-table3 must be done automaticaly. I want to avoid duplicate records.
The final situation I want is given in red text.
The relationships between the tables are as follows
-------------------------------------------------------------
Table1 (PK)ID-Userinfo [ONE] <------------> [MANY] Table3 ID-Userinfo
Table3 (PK)ID-GroupInfo [MANY] <------------> [ONE] Table2 (PK)ID-GroupInfo
Table1: UserInfo
------------------------------
(PK)ID-Userinfo UserName
1 John
2 Bill
3 Allison
Table2: GroupInfo
------------------------------
(PK)ID-GroupInfo GroupName
1 Group_A
2 Group_B
3 Group_C
4 Group_E
Table3: MemberOf
------------------------------
(PK)ID-MemberOf ID-UserInfo ID-GroupInfo
1 1 1
2 1 2
3 2 2
4 2 3
5 3 1
6 3 4
I hope you can help me cracking this nut.
Thx in advance. Greetings Fred
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Oct 26, 2006
Can Somebody please show me how to acheive this, using the order details in Northwinddatabase or any other good example. as much details as possible. Many Thanks!
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Nov 14, 2003
is it possible to link a table with odbc into sql server?
it would be nice to link an MS Access table into sql server where i could use stored procedures to access the MS Access table.
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Apr 25, 2000
I have used to following Microsoft supplied code to create a link to
SQL server from access: (Is there a way to use a DSN-less connection at comment below? If not is there a way to create a DSN using code?
-------------------------------------------------------------------------
Sub ClientServerX3()
Dim dbsCurrent as Database
Dim tdRoy as TableDef
Set dbsCurrent = CurrentDb
Set tdfRoy = dbsCurrent.CreateTableDef("Roy")
tdfRoy.Connect = "ODBC;DATABASE=pubs;UID=sa;PWD=;DSN=Publishers"
***************IS THERE ANYWAY TO USE AN OLEDB (OR OTHER DSN-LESS)
***************CONNECTION HERE? How??
tdfRoy.SourceTableName = "Royalties"
dbsCurrent.TableDefs.Append tdfRoy
End Sub
Thanks, I really appreciate the help
Sam
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Feb 26, 2007
I'm trying to find how to link to an Access table from within SQL Server. I know I have seen it once, but can not remember where I saw it. I'm using SQL Server 2005. TIA,
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Jun 21, 2015
Previously same records exists in table having primary key and table having foreign key . we have faced 7 records were lost from primary key table but same record exists in foreign key table.
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Jan 23, 2008
Hi,
To all, How I can get SQL table to practice?
Regards,
Sherazi
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Jul 23, 2005
What is the best way to setup relationships between one lookup tableand many other tables. The tables did not have any lookup tablerelationships which I am adding. One lookup table is used for same datain several different places.To use one lookup tables with several tables, I had to disable "CascadeUpdate" and only have "enforce relationships for updates and inserts"checked.Any pros/cons?Thanks in advance.P
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Apr 24, 2015
Background:
* SQL Server 2008 R2
* Database was created from a third party product. The product writes to the 3 tables that I need to make changes to 24/7 and downtime is not an option. All changes must be done live.
* Database overall size is ~200 GB
* The 3 tables I must update make up ~190 GB of that space.
* Tables have no primary key or ID columns. Therefore, the data is highly fragmented.
* Of the ~190 GB of space allocated for the tables, there is roughly 70 GB of actual data.
* Rows of the table are not guaranteed to be unique. In fact, on one of the tables, tests were ran with a small sample of data and duplicates were very much evident.
What I'm trying to accomplish here is to get an ID column added to the 3 tables and set that ID field as the primary key. Doing so will force the data to become much less fragmented than it is currently and with purging and new inserts, eventually fragmentation will be nearly non-existent.
Problem:
Making table changes on tables this large while data is constantly being added poses many risks and can cause data loss. This was tried on a smaller table than these three and the entire table was lost in the process. Restore from backup was needed to get back to most recent log backup point.
Original Solution:
My original plan was to create a backup of each table and run the script below to migrate the majority of the data temporarily into the new table. I could then update the original table (which now would contain much less data) and then migrate the data back.
CREATE TABLE #temp
(
MsgDate varchar(10)
,MsgTime varchar(8)
,MsgPriority varchar(30)
,MsgHostname varchar(255)
[Code] ....
Original Solution Problem:
The problem with the solution above is that it calls the DELETE function on the original table using the values from the temporary table. When there are duplicate rows, which have not all been inserted into the backup table yet, they will all be removed from the original table because there is nothing unique to separate them out. In my testing, I had 10,000 rows in the original table and ended up with 9,959 rows in the backup table.
Question 1: Is my approach to making these table changes reasonable?
Question 2a: If so, how can I make sure I don't lose data as part of this temporary migration of the data to my backup tables?
Question 2b: If not, what would be a better approach that isn't going to cause disruption to the application that INSERTs data 24/7 and won't have any risk of data loss?
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Aug 15, 2006
Hi All,
I have created a table using VIEWS in SQL server 2005, now i want to be ablle to edit it in a datagrid but i cannot do so as i there is no primary key!
now does anybody know how to set a primary key constraint so i can set one of the fields as a primary key to identify the row?
many thanks
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Apr 30, 2015
Environment: Microsoft SQL Server Standard Edition (64-bit), 10.0.5520.0
I was doing a code review for another developer and came across this code:
CREATE TABLE dbo.#ABC
(
ReportRunTime DATETIME
,SourceID VARCHAR(3)
,VisitID VARCHAR(30)
,BaseID VARCHAR(25)
[Code] ....
This EXECUTES with no error or warning message.However, if I change this to CREATE the PK in an ALTER TABLE statement, I get the (expected by me) error:
CREATE TABLE dbo.#ABC
(
ReportRunTime DATETIME
,SourceID VARCHAR(3)
,VisitID VARCHAR(30)
,BaseID VARCHAR(25)
,OccurrenceSeqID INT
[code]...
==> Msg 8111, Level 16, State 1, Line 17 Cannot define PRIMARY KEY constraint on nullable column in table '#ABC'.
==> Msg 1750, Level 16, State 0, Line 17 Could not create constraint. See previous errors.
(note: As the #ABC table is an actual copy of a few of the columns in a "permanent" table, I will likely change the definition as follows such that the columns are defined to match the names / datatypes / NULLability:
SELECT TOP 0
CAST('01-01-1980' AS DATETIME) AS [ReportRunTime]
,SourceID
,VisitID
,BaseID
,OccurrenceSeqID
[Code] .....
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Oct 2, 2015
In a special request run, I need to update locker and lock tables in a sql server 2012 database, I have the following 2 table definitiions:
CREATE TABLE [dbo].[Locker](
[lockerID] [int] IDENTITY(1,1) NOT NULL,
[schoolID] [int] NOT NULL,
[number] [varchar](10) NOT NULL,
[lockID] [int] NULL
CONSTRAINT [PK_Locker] PRIMARY KEY NONCLUSTERED
[code]....
The locker table is the main table and the lock table is the secondary table. I need to add 500 new locker numbers that the user has given to me to place in the locker table and is uniquely defined by LockerID. I also need to add 500 new rows to the corresponding lock table that is uniquely defined in the lock table and identified by the lockid.
Since lockid is a key value in the lock table and is uniquely defined in the locker table, I would like to know how to update the lock table with the 500 new rows. I would then like to take value of lockid (from lock table for the 500 new rows that were created) and uniquely place those 500 lockids uniquely into the 500 rows that were created for the lock table.
I have sql that looks like the following so far:
declare @SchoolID int = 999
insert into test.dbo.Locker ( [schoolID], [number])
select distinct LKR.schoolID, A.lockerNumber
FROM [InputTable] A
JOIN test.dbo.School SCH ON A.schoolnumber = SCH.type and A.schoolnumber = @SchoolNumber
JOIN test.dbo.Locker LKR ON SCH.schoolID = LKR.schoolID
AND A.lockerNumber not in (select number from test.dbo.Locker where schoolID = @SchoolID)
order by LKR.schoolID, A.lockerNumber
I am not certain how to complete the rest of the task of placing lockerid uniquely into lock and locker tables?
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Oct 19, 2015
How to add a primary key for existing column in the table
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Aug 28, 2002
Hi all,
Can anyone suggest me on Adding primary key to a table which has already a primary key.
Thanks,
Jeyam
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Dec 11, 2007
Hi All,
I am using SQL Server 2000 Enterprise Edition fully patched. Database is in Simple Recovery mode.
I need to change a column's data type from "int(4)" to "smallint(2)". I know for sure that there will be no data (precision) lost, because I know the possible values that this column could have.
My problem is that the table I am dealing with has 600,000,000 records in it. I dropped all indexes before I tried to alter the table. But still it is taking forever and filling up my 280GB disk with transaction log file.
I know that in Oracle, if I want I can turn off logging and do these kind of modifications relatively faster.
I was wondering if there is a way of disabling logging before running this alter command.
What is the best practice to handle a situation of this sort?
I appreciate your help.
Thanks in advance,
Sinan Topuz
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Dec 28, 2006
Hi,
I am using a SQL back end to dynamically populate an asp.net report/page.
As the data I'm interrogating is created from a tree control, I'm having to use a recursive function to retrieve the data into a series of ID values. This all happens at the moment in a DataTable manipulated with c# code. So my ID values end up in this datatable.
My problem is that I am then performing a crosstab query in SQL Server 2000 and these ID are required as part of that query.
Should I create a temp table and join this into the query or should i feed in a series of ID values into a where clause?
Any help gratefully appreciated.
Thanks.
John
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Jan 13, 2013
Or can it record before and after column changes based on the LSN only?
An extract from a file based legacy accounting system is performed every night. The system does not have a primary key because transactions are managed through program code. (the more things change...). The extract is copied to text in Unix and FTP'd to Windows, where the file is loaded into SQL Server by kill & fill. Because of the expense of modifying the source system, there is enormous inertia/resistance to injecting a primary key at the source, so kill & fill it stays.
In reading about Change Data Capture, it seemed to me that column level insert update and delete are stored in tables that remember the before and after content of each column tracked. In my reading I have seen many references to the LSN to decide when and what to record as changed, but I have not seen any refereference to the necessity of a primary key for Change Data Capture to work. This is in contrast to replication, where the requirement for the existence of a primary key is made plain.
Is it possible to use Change Data Capture against a table without a primary key? How to use it to change the extract from kill and fill to incremental.
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Sep 1, 2014
Looking to improve performance of the following code.
It basically generates future days for each dog. So there is a dog table and a day table with every day.
These 2 table cross join and then fill in missing rows. As time moves i will fill in further future dates but will need the initial insert to be a reasonable query.
All columns are covered by index's but the queries at the end take quite a long time. I would hope for index scan to just point out the missing rows especially on the final query.
How to make the last query as fast as possible.
IF OBJECT_ID('dbo.[AllDates]', 'U') IS NOT NULL
DROP TABLE dbo.[AllDates]
CREATE TABLE dbo.[AllDates] (
[Date] date not null PRIMARY KEY
)
;WITH Dates AS
[Code] .....
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Jun 9, 2015
How to copy a table from one server to another server with primary and foreign key constraints.
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