I want to have a column in which the default timestamp is added when an insertion is done. I have done that in MySQL using choosing default timestamp option. How do I do that in SQL Server?
ALTER TABLE table_name ADD InsertTime DATETIME DEFAULT GETDATE()
ALTER TABLE [table] ADD [CreationTimeStampUTC] DATETIME DEFAULT(GETUTCDATE())
Or you could do the same with GETDATE(), which I think I've seen more in real-world code. Note, of course, that GETDATE() will be valued with the current server time of the SQL Server, and may or may not match up with the current time of the web server if you have one, or particularly the client's machine. Obviously there's no issue with that, just make sure you're aware of the implications ahead of time. You could also store this timestamp as a DATETIMEOFFSET to rid yourself of some of those concerns, but since you're speaking explicitly of on-server default values, I think UTC is perfectly sufficient.
What you're looking for is a default constraint. How you add it depends on whether the column already exists or not. If it doesn't, you can add the column and the constraint in one shot like so:
alter table dbo.yourTable
add [NewColumn] datetime
constraint [DF_NewColumn] default (getdate());
If the column already exists, you can attach a default to it like so:
alter table dbo.yourTable
add constraint [DF_ExistingColumn] default (getdate()) for [ExistingColumn];
Finally, if the table doesn't yet exist, you can add the constraint to the table definition:
create table dbo.yourTable (
NewColumn datetime not null constraint [DF_NewColumn] default (getdate())
)
Note: in all cases, I gave the constraint a name. You can choose not to, but then you'll eventually get a huffy DBA asking why her database comparison is a mess because the constraint names don't match up between dev and prod. :)
Related
I am changing the type of a column from bit to tinyint. After that, I want to define the new default value and a new constraint for it. How do I do this? I know how to do it if the column does not exist, but for an existing column my approaches failed so far.
Thanks! :)
Try something like this:
-- change the column type
ALTER TABLE dbo.gradytest
ALTER COLUMN YourColumn TINYINT NULL
-- add a named default constraint
ALTER TABLE dbo.gradytest
ADD CONSTRAINT DF_YourColumn_Default DEFAULT(4) FOR YourColumn
I've got a table that collects forms submitted from our website, but for some reason, when they created the table, they didn't put a timestamp in the table. I want it to enter the exact date and time that the record was entered.
I know it's in there somewhere, but I can't seem to find how to set the default value (like in Access, you use getNow() or Now()) but I don't know where to put it.
For modifying an existing column in an existing table:
ALTER TABLE YourTable ADD CONSTRAINT DF_YourTable DEFAULT GETDATE() FOR YourColumn
This can also be done through the SSMS GUI.
Put your table in design view (Right click on table in object explorer->Design)
Add a column to the table (or click on the column you want to update if it already exists)
In Column Properties, enter (getdate()) in Default Value or
Binding field as pictured below
In that table in SQL Server, specify the default value of that column to be CURRENT_TIMESTAMP.
The datatype of that column may be datetime or datetime2.
e.g.
Create Table Student
(
Name varchar(50),
DateOfAddmission datetime default CURRENT_TIMESTAMP
);
While the marked answer is correct with:
ALTER TABLE YourTable ADD CONSTRAINT DF_YourTable DEFAULT GETDATE() FOR YourColumn
You should always be aware of timezones when adding default datetime values in to a column.
Say for example, this datetime value is designed to indicate when a member joined a website and you want it to be displayed back to the user, GETDATE() will give you the server time so could show discrepancies if the user is in a different locale to the server.
If you expect to deal with international users, it is better in some cases to use GETUTCDATE(), which:
Returns the current database system timestamp as a datetime value. The database time zone offset is not included. This value represents the current UTC time (Coordinated Universal Time). This value is derived from the operating system of the computer on which the instance of SQL Server is running.
ALTER TABLE YourTable ADD CONSTRAINT DF_YourTable DEFAULT GETUTCDATE() FOR YourColumn
When retrieving the values, the front end application/website should transform this value from UTC time to the locale/culture of the user requesting it.
Disallow Nulls on the column and set a default on the column of getdate()
/*Deal with any existing NULLs*/
UPDATE YourTable SET created_date=GETDATE() /*Or some sentinel value
'19000101' maybe?*/
WHERE created_date IS NULL
/*Disallow NULLs*/
ALTER TABLE YourTable ALTER COLUMN created_date DATE NOT NULL
/*Add default constraint*/
ALTER TABLE YourTable ADD CONSTRAINT
DF_YourTable_created_date DEFAULT GETDATE() FOR created_date
The syntax for this when creating a new table is:
CREATE TABLE MyTable
(
MYTableID INT IDENTITY(1,1),
CreateDate DATETIME NOT NULL CONSTRAINT DF_MyTable_CreateDate_GETDATE DEFAULT GETDATE()
)
This works for me...
ALTER TABLE [accounts]
ADD [user_registered] DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP ;
This also works:
CREATE TABLE Example(
...
created datetime default GETDATE()
);
Or:
ALTER TABLE EXAMPLE ADD created datetime default GETDATE();
This worked for me. I am using SQL Developer with Oracle DB:
ALTER TABLE YOUR_TABLE
ADD Date_Created TIMESTAMP DEFAULT CURRENT_TIMESTAMP NOT NULL;
Let's say you create a database table for a registration system.
IF OBJECT_ID('dbo.registration_demo', 'U') IS NOT NULL
DROP TABLE dbo.registration_demo;
CREATE TABLE dbo.registration_demo (
id INT IDENTITY PRIMARY KEY,
name NVARCHAR(8)
);
Now a couple people register.
INSERT INTO dbo.registration_demo (name) VALUES
('John'),('Jane'),('Jeff');
Then you realize you need a timestamp for when they registered.
If this app is limited to a geographically localized region, then you can use the local server time with GETDATE(). Otherwise you should heed Tanner's consideration for the global audience with GETUTCDATE() for the default value.
Add the column with a default value in one statement like this answer.
ALTER TABLE dbo.registration_demo
ADD time_registered DATETIME DEFAULT GETUTCDATE();
Let's get another registrant and see what the data looks like.
INSERT INTO dbo.registration_demo (name) VALUES
('Julia');
SELECT * FROM dbo.registration_demo;
id name time_registered
1 John NULL
2 Jane NULL
3 Jeff NULL
4 Julia 2016-06-21 14:32:57.767
To make it simpler to follow, I will summarize the above answers:
Let`s say the table is called Customer
it has 4 columns/less or more...
you want to add a new column to the table where every time when there is insert... then that column keeps a record of the time the event happened.
Solution:
add a new column, let`s say timepurchase is the new column, to the table with data type datetime.
Then run the following alter:
ALTER TABLE Customer ADD CONSTRAINT DF_Customer DEFAULT GETDATE() FOR timePurchase
In SQLPlus while creating a table it is be like as
SQL> create table Test
( Test_ID number not null,
Test_Date date default sysdate not null );
SQL> insert into Test(id) values (1);
Test_ID Test_Date
1 08-MAR-19
Basically I want to use uniqueidentifier in similar way as identity. I don't want to insert values into it, It should just insert values automatically, different value for each row.
I'm not able to set autoincrement on columns of type uniqueidentifier(the property 'autoincrement' is set to false and is not editable).
Or even better: use the newsequentialid() as the default for your UNIQUEIDENITIFER column. That'll give you a somewhat sequential series of GUIDs.
CREATE TABLE dbo.YourTable
(SerialID UNIQUEIDENTIFIER
CONSTRAINT DF_SerialID DEFAULT newsequentialid(),
.... (other columns)......
)
Trouble is: newsequentialid is only available as a column default - you cannot call it as a function or anything. But that seems to fit your requirements.
UPDATE: there appears to be an acknowledged bug in SQL Server Management Studio that prevents specifying newsequentialid() as the default for a column in the interactive table designer.
See: http://social.msdn.microsoft.com/Forums/en-US/sqltools/thread/cad8a4d7-714f-44a2-adb0-569655ac66e6
Workaround: create your table without specifying any default, and then type in this T-SQL statement in a normal query window and run it:
ALTER TABLE dbo.YourTable
ADD CONSTRAINT DF_SerialID DEFAULT newsequentialid() FOR SerialID
That should do the trick!
I guess you mean in SQLServer and not C#...
Set the column as PRIMARY KEY and ROWGUID
RowGuid http://img341.imageshack.us/img341/8867/sqlserverrowguid.png
I think
CREATE TABLE dbo.YourTable
(
SerialID UNIQUEIDENTIFIER PRIMARY KEY DEFAULT newsequentialid()
)
is simplier
Use NewID() as the default value. At least this is what you would do for SQL Server.
I have a table [Product] with a column [CreateTime] datetime null, and is has some data already.
How can I set the column [CreateTime] 's default value to getdate(), and make the new added data to have a default value getdate() for column [CreateTime].
You cannot change a default - you will need to first drop it, and then recreate it.
In order to drop it, you need to know its name, and then use
ALTER TABLE dbo.Product
DROP CONSTRAINT yourOldDefaultConstraint
Once you've done that, you can add a new default constraint, and in order to apply it to existing rows, use the "WITH VALUES" part:
ALTER TABLE dbo.Product
ADD CONSTRAINT NewDefaultConstraintName
DEFAULT GetDate() FOR CreateTime WITH VALUES
Oops - sorry, the "WITH VALUES" only seems to work if you create a DEFAULT constraint at the time you create the table, or if you add the column - it doesn't seem to get applied to an existing column.
In this case you would just have to follow your ALTER TABLE statement with something like this:
UPDATE dbo.T_Product
SET CreateTime = GETDATE()
WHERE CreateTime IS NULL
That should do the trick, too!
Marc
In SQL Server 2000/2005,
Is it possible to force the default value to be written to already existing rows when adding a new column to a table without using NOT NULL on the new column?
You need two statements. First create the column with not null. Then change the not null constraint to nullable
alter table mytable add mycolumn varchar(10) not null default ('a value')
alter table mytable alter column mycolumn varchar(10) null
I understand your question, but you are saying that for future records, NULL (unknown, indeterminate or whatever your semantics are) is acceptable (but if it is left off in an insert, there will be a default), but that for all the existing data, you are going to go ahead and assign it the default.
I would have to look hard at this situation and ask why you are even going to allow NULLs in future records at all - given none of the historical records will have it, and there is a default in place for future records.
I doubt it.
http://msdn.microsoft.com/en-us/library/ms190273(SQL.90).aspx
The approach recommended by Microsoft is as follows (taken from the url above)
UPDATE MyTable SET NullCol = N'some_value' WHERE NullCol IS NULL
ALTER TABLE MyTable ALTER COLUMN NullCOl NVARCHAR(20) NOT NULL
ALTER TABLE {TABLENAME}
ADD {COLUMNNAME} {TYPE} {NULL|NOT NULL}
CONSTRAINT {CONSTRAINT_NAME} DEFAULT {DEFAULT_VALUE}
[**WITH VALUES]**
WITH VALUES can be used to store the default value in the new column for each existing row in the table.
more detail on MSDN link .
https://msdn.microsoft.com/en-in/library/ms190273.aspx