I right click on my table in ssms 2008 and select Script Table as / Drop and Create Table to new window and I try to run the script but get an error:
Could not drop table because it is referenced by a foreign key constraint
What was the point of the Drop and Create generate script then?
Thanks,
rod.
The point of the Drop and Create generate script is exactly what you'd think - it gives you an easy way to script out dropping and re-creating a table. However you can't drop a table if other tables reference it via foreign key constraints, which is why you're getting the error message.
If you're just trying to add a column, you can right-click the table in Enterprise Manager and click Modify and just add the column in design view. There's no need to drop the table just to add a column. (And it's especially an awful approach if the table has data in it.)
The easiest way to add a column to an existing table? Write the ALTER TABLE statement yourself instead of relying on SQL Server Management Studio to do it for you:
ALTER TABLE YourTableName
ADD ColumnName int
Related
I want to alter column within the table to be NULL from NOT NULL.
The problem is that table has one constraint, one trigger and 4 indexes.
Can I somehow alter that column without dropping and recreating everything?
exec sys.sp_depends 'object_name'
List all dependencies and then drop them an recreate everything.
SQL Managements studio offer option with SCRIPT AS CREATE and you can save all views, triggers, tables as backup...
On our original design we screwed up a foreign key constraint in our table. Now that the table is full of data we cannot change it without dropping all of the records in the table. The only solution I could think of is to create a backup table and put all of the records in there, then delete all the records, alter the table and start adding them back. Any other (BETTER) ideas? Thanks!
Using MS SQL Server
I'm a bit late, just for reference.
If You are using SQL Server Management Studio, You could generate a DROP and RECREATE script with "Keep schema and data" option.
Right click on the desired DB in object explorer
Tasks > Generate scripts
Select the table you want to script
Then clicking on Advanced button
"Script DROP and CREATE" ->"Script DROP and CREATE"
"Types of data to script" -> "Schema and data"
Hope this helps
Here's some pseudo-code. No need to make a backup table, just make a new table with the right constraint, insert your records into it, and rename.
CREATE TABLE MyTable_2
(...field definitions)
<add the constraint to MyTable_2>
INSERT INTO MyTable_2 (fields)
SELECT fields
FROM MyTable
DROP TABLE MyTable
exec sp_rename 'MyTable2', 'Mytable'
Using SQL Server Management Studio (SSMS), you can use it's table designer to specify the final condition of the table. Before saving the changes, have it generate the change script and save that script. Cancel out of the design window, open the script and review it. SSMS may already have generated a script that does everything you need, fixing the primary-foreign key relationship while preserving all existing data. If not, you will have a script, already started, that performs most of what you need to do and should be able to modify it for your needs.
This is your only solution.
Create the backup table, empty the original one, modify the table and then insert step-by-step until you find a violation.
Update All Schema Database Old by new Schema Database .
Create script (Right click on the desired DB in object explorer Tasks > Generate scripts -> select option select specific database objects and tables ->next -> advanced-> option Type of data to script Data only -> ok ->next ->next.) to data only and backup Database to old database
Drop database old and create new database and make new DB is empty .
Excute script of Old Data only on new database .
Is it possible to copy a table (with definition, constraints, identity) to a new table?
Generate a CREATE script based on the table
Modify the script to create a different table name
Perform an INSERT from selecting everything from the source table
No, not really, you have to script it out, then change the names
you can do this
select * into NewTable
FROM OldTable
WHERE 1 =2 --if you only want the table without data
but it won't copy any constraints
It's not the most elegant solution, but you could use a tool like the free Database Publishing Wizard from Microsoft.
It creates an SQL script of the table definition including data and including indexes and stuff. But you would have to alter the script manually to change the table name...
Another possibility:
I just found this old answer on SO.
This script is an example to script the constraints of all tables, but you can easily change it to select only the constraints of "your" table.
So, you could do the following:
Create the new table with data like SQLMenace said (select * into NewTable from OldTable)
Add constraints, indexes and stuff by changing this SQL script
Whenever I want to add a column to a table it usually goes something like this:
Fire up SQL Server Management Studio (SSMS)
Select "Design" on the table I want to add the column to
Add the new column to the table
Save
Get an error that SSMS can't save because it would need to drop the table (and it can't because the the table has foreign keys on it).
Get frustrated that I forgot that this is something that SSMS can't do
Construct an alter table command by hand to add the column
Move on with life.
This time I am adding a step between numbers 6 and 7. I thought I would ask why SSMS can't make a simple alter table statement to add my new column in.
(In case it matters I am running SSMS 2008 against SQL Server 2008.)
Alternatively, you can go to Tools-->Options-->Designers-->Table and Database Designers and uncheck "Prevent saving changes that require table re-creation"
Problem solved.
Here's an explanation from MSDN: http://support.microsoft.com/default.aspx/kb/956176.
When you change a table so that you
alter the metadata structure of the
table, and then you save the table,
the table must be re-created based on
these changes.
I wanted to modify a column in a sql server 2005 table to IDENTITY(1,1)
Incidentally this table is empty and the column to be changed is a primary key.
This column is also a foreign key for two other tables.
After googling I found that you cannot use Alter table syntax to modify a column and make it an indentity column.
Link #1 : How do I add the identity property to an existing column in SQL Server
Link #2 : Adding an identity to an existing column -SQL Server
I ended up checking the dependent tables (2 of them) removing the foreign keys (generated the script from SSMS) then dropping the main table then re-creating with identity. (could try the rename option here as well)
Then re-created the foreign keys for the earlier dependent two tables.
But all this was manual work, any scripts or SPs out there to make this easier.
Ideally all these steps would be done by such a script/tool/utility:
Check dependent tables keys
Generate Create and drop foreign key scripts for this
Generate create script for the main table
drop the main table (or rename the table if the table has data)
re-create the table with identity column enabled
re-create foreign keys
You can use SSMS to generate a script (Edit a table, save script), but otherwise it's a manual process as you identified.
The SSMS scripts will pick up dependencies etc. For this kind of work, I tend to use SSMS to generate a basic script, pimp it a bit, run it carefully, then use a comparison tool (such as Red Gate compare) to generate a safer version.
Edit: The SSMS error is not an error, it's a safety check that can be switched off
(This is merely a follow-up to gbn's post with more details -- it isn't all that easy to figure this stuff out.)(
It isn't impossible to write a utility to do this, just very complex and very hard. Fortunately, Microsoft has already done it -- its called SSMS (or SMO?). To generate such a script:
In the Object Explorer, drill down to the database and table that you want to modify
Right click and select Design
Make the desired changes to the one table in the design screen. It's reasonably intuitive.
To add/remove the identity property, select the column in the upper pane, and in the lower pane/"Column Properties" tab, expand and configure the settings under "Identity Specification".
To generate a script to implement all your changes, incorporating all the dependent key changes, click on the "Generate Change Script" toolbar button. This is also an option under the "Table Designer" menu.
I also do this to generate scripts (that I later modify--SSMS doesn't always produce the most efficient code.) Once done, you can exit out without saving your changes -- leaving you a DB you can test your new script on.
drop the pk and build the same datatype column
copy the data of the column which you want to set identity to the new column.
drop the old column
reset primary key
ALTER TABLE UserRole
DROP CONSTRAINT PK_XX
ALTER TABLE XX
ADD newX int not null identity(1,1) primary key
update XX set newX = oldX
alter table XX
DROP COLUMN oldX
this is the simplest way to set identity column.
if you don't want to use the long generated script.