I'm using code first migrations with entity framework. I've got a column that was created a few migrations ago called Amount which is marked as 'required', that stores an integer value. I've now been told, this needs to be a decimal. When I change the datatype in my context and run 'Add-Migration, it creates the migration file as I expect.
When I run Update-Database, it gives me the following error
The object 'DF_Products_ProductsTrack__522F1F86' is dependent on
column 'Amount'. ALTER TABLE ALTER COLUMN Amount failed because one or
more objects access this column.
I've managed to write some custom SQL to do this manually:
ALTER TABLE Products
DROP CONSTRAINT [DF__Products__ProductsTrack__522F1F86]
GO
ALTER COLUMN Amount decimal(18,2)
However, this is no good as I need the datatype changed as part of my migrations. I am write in assuming the dependency is because of the 'Required' attribute that was initially assigned to it? How do I change the type using 'normal' migration techniques?
Related
I want to alter all varchar columns in my database to nvarchar, using a T-SQL script.
There are a lot of dependencies (keys, constraints, and views) that cause problems when trying to alter.
The object 'X' is dependent on column 'Y'. ALTER TABLE ALTER COLUMN 'Y' failed because one or more objects access this column.
My unsuccessful attempts: forcing a change with PowerShell, and creating a generate script for the whole database and using that to create a copy with all the changes I need. These attempts didn't work, because I lost the table data and the generate scripts were too big for any program to handle.
How does one create all DROP and CREATE scripts of the objects that cause problems when trying to alter to make the changes and recreate the database schema like it was before altering?
In HSLQDB v 2.3.1 there is a create type clause for defining UDTs. But there appears to be no alter type clause, as far as the docs are concerned (and the db returns a unexpected token error if I try this).
Is it possible to amend/drop a UDT in HSQLDB? What would be the best practice, if for example I originally created
create type CURRENCY_ID as char(3)
because I decide I'm going to use ISO codes. But then I actually decide that I'm going to store the codes as integers instead. What is the best way to modify the schema in my db? (this is a synthetic example, obviously I wouldn't use integers in this case).
I guess I might do
alter table inventory alter column ccy set data type int
drop type CURRENCY_ID
create type CURRENCY_ID as int
alter table inventory alter column ccy set data type CURRENCY_ID
but is there a better way to do this?
After trying various methods, I ended up writing a script to edit the *.script file of the database directly. It's a plain text file with SQL commands that recreates the DB programmatically. In detail:
open db, shutdown compact
Edit the script file: replace the type definition, e.g. create type XXX as int to create type XXX as char(4)
For each table, replace the insert into table XXX values (i,...) with insert into table XXX values('str',...). This was done with a script that had the mappings from the old (int) value into the new (char) value.
In my particular case, I was changing a primary key, so I had to remove the identity directive from the create table statement, and also I had to remove a line that had a alter table XXX alter column YYY restart sequence 123.
save and close script file, open db, shutdown compact
This isn't great, but it worked. Advantages :
Ability to re-define UDT.
Ability to map the table values programmatically.
Method is generic and can be used for other schema changes, beside UDTs.
Cons
No checking that schema is consistent (although it does throw up errors if it can't read the script).
Dangerous when reading file as a text file. e.g. what if I have a VARCHAR column with newlines in it? When I parse the script file and write it back, this would need to be escaped.
Not sure if this works with non-memory DBs. i.e. those that don't only have a *.script file when shutdown.
Probably not efficient for large DBs. My DB was small ~ 1MB.
Could we change attribute's data type when the database table has record in SQL?
I am using Microsoft Management Studio 2008. The error that i am getting is:
** Error converting data type nvarchar to float. **
In short: It is possible with alter column command ONLY if the altered data type is compatible with newly modified one. In addition, it is recommended to be done with transaction.
For example: You may change a column from a varchar(50) to a nvarchar(200), with a script below.
alter table TableName
alter column ColumnName nvarchar(200)
Edit: Regarding your posted error while altering column type.
** Error converting data type nvarchar to float. **
One way would be to create a new column, and convert all good (convertible and compatible) records to new column. After that you may wanna to clean-up the bad records that do not convert, delete old column and re-name your newly added and populated column back to the original name. Important: use testing environment for all this manipulations first. Usually, playing with productions tables turns to be a bad practice to screw things up.
References to look for more discussions on similar SE posts:
Change column types in a huge table
How to change column datatype in SQL Server database without losing data
Obviously, there is no default conversion to your new datatype. One solution could be to create a second column with the requested type, and write your own conversion function. Once this done, delete the first column and rename the second one with the same name.
Things to consider: How big your table is. You then use the alter table syntax. We do not know what data type you want to change, so just for e.g.
alter column:
Alter Table [yourTable] Alter column [yourColumn] varchar(15)
You could also try to add a new column and then update that column using your old column. Drop the old column. Rename the new column. This is a safe better way, becasue at times the data that you hold might not react well to the new data type...
A post to look into for ideas: Change column types in a huge table, How to change column datatype in SQL database without losing data
Alter datatype of that column ..But In general sql wont allow to channge.It will prompt u drop that column..There is setting to achive that thing.
Go to Tool->Option->designers->Table and Database designers and Uncheck Prevent saving option.I m taking abt sql server 2008R2.Now u can easily alter data type.
Here's a strange one. I'm using SubSonic 2.0.3 to insert a new row into a given table.
The table includes an int identity field that is set up properly in the database (Identity seed = 1, Identity increment = 1). Obviously I do not explicitly set this value before calling .Save().
Ever since I rebuilt my development DB (copying from my prod DB), the .Save() fails with the message:
"The INSERT statement conflicted with the CHECK constraint \"repl_identity_range_tran_661577395\". The conflict occurred in database \"blah\", table \"dbo.ScheduledEmails\", column 'MyIdentity'"
The database is replicated, and I didn't explicitly create that constraint. To be honest, I don't understand the constraint, since the condition is ([MyIdentity]>(7) AND [MyIdentity]<(20000)). The constraint from the Prod DB has different numbers, but it's the same format as this one from my Dev DB.
Any clues about this bizarre issue?
I'm trying to change the size of a column in sql server using:
ALTER TABLE [dbo].[Address]
ALTER COLUMN [Addr1] [nvarchar](80) NULL
where the length of Addr1 was originally 40.
It failed, raising this error:
The object 'Address_e' is dependent on column 'Addr1'.
ALTER TABLE ALTER COLUMN Addr1 failed because one or more objects access
this column.
I've tried to read up on it and it seems that because some views are referencing this column and it seems that SQL Server is actually trying to drop the column that raised the error.
Address_e is a view created by the previous DB Administrator.
Is there any other way I can change the size of the column?
ALTER TABLE [table_name] ALTER COLUMN [column_name] varchar(150)
The views are probably created using the WITH SCHEMABINDING option and this means they are explicitly wired up to prevent such changes. Looks like the schemabinding worked and prevented you from breaking those views, lucky day, heh? Contact your database administrator and ask him to do the change, after it asserts the impact on the database.
From MSDN:
SCHEMABINDING
Binds the view to the schema of the underlying table or tables. When
SCHEMABINDING is specified, the base
table or tables cannot be modified in
a way that would affect the view
definition. The view definition itself
must first be modified or dropped to
remove dependencies on the table that
is to be modified.
If anyone wants to "Increase the column width of the replicated table" in SQL Server 2008, then no need to change the property of "replicate_ddl=1". Simply follow below steps --
Open SSMS
Connect to Publisher database
run command -- ALTER TABLE [Table_Name] ALTER COLUMN [Column_Name] varchar(22)
It will increase the column width from varchar(x) to varchar(22) and same change you can see on subscriber (transaction got replicated). So no need to re-initialize the replication
Hope this will help all who are looking for it.
See this link
Resize or Modify a MS SQL Server Table Column with Default Constraint using T-SQL Commands
the solution for such a SQL Server problem is going to be
Dropping or disabling the DEFAULT Constraint on the table column.
Modifying the table column data type and/or data size.
Re-creating or enabling the default constraint back on the sql table column.
Bye
here is what works with the version of the program that I'm using: may work for you too.
I will just place the instruction and command that does it. class is the name of the table. you change it in the table its self with this method. not just the return on the search process.
view the table class
select * from class
change the length of the columns FacID (seen as "faci") and classnumber (seen as "classnu") to fit the whole labels.
alter table class modify facid varchar (5);
alter table class modify classnumber varchar(11);
view table again to see the difference
select * from class;
(run the command again to see the difference)
This changes the the actual table for good, but for better.
P.S. I made these instructions up as a note for the commands. This is not a test, but can help on one :)
Check the column collation. This script might change the collation to the table default. Add the current collation to the script.
You can change the size of the column in 3 steps:
Alter view Address_e and take in comment column /*Addr1*/
Run your script
ALTER TABLE [dbo].[Address]
ALTER COLUMN [Addr1] [nvarchar](80) NULL
Then again alter view Address_e, in order to uncomment column Addr1