SQL UniqueIdentifier

Question

I have a table called UserCredentials and it has a uniqueidentifier column [UserCredentialId]. When I try to create a new user, I get 00000000-0000-0000-0000-000000000000 in my first try, then when I try adding another user, it says PK cannot be duplicated. At first I had a hard time guessing what does it mean but, I think its because of my uniqueidentifier is not generating random id.

What to do?

EDIT

Here is my SQL table structure:

CREATE TABLE [dbo].[UserCredential]( [UserCredentialId] [uniqueidentifier] NOT NULL, [UserRoleId] [int] NOT NULL, [Username] [varchar](25) NOT NULL, [Password] [varchar](50) NOT NULL, [PasswordSalt] [varchar](max) NOT NULL, [FirstName] [varchar](50) NOT NULL, [LastName] [varchar](50) NOT NULL, [PayorCode] [varchar](20) NOT NULL, [ProviderCode] [varchar](50) NULL, [CorporationCode] [varchar](50) NULL, [Department] [varchar](50) NULL, [Status] [varchar](1) NOT NULL, [DateCreated] [datetime] NOT NULL, [DateActivated] [datetime] NULL, [Deactivated] [datetime] NULL, [DateUpdated] [datetime] NULL, [CreatedBy] [varchar](50) NOT NULL, [UpdatedBy] [varchar](50) NOT NULL, [EmailAddress] [varchar](50) NULL, [ContactNumber] [int] NULL, [Picture] [varbinary](max) NULL, CONSTRAINT [PK_UserCredential_1] PRIMARY KEY CLUSTERED ( [UserCredentialId] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] ) ON [PRIMARY]

I already set it to (newid()) but still not working.

I think he set the DefaultValueForBinding in the field properties list of the field to NEWID(). — Ross Bush
– Ross Bush, Commented May 14, 2014 at 2:21

marc_s · Accepted Answer · 2014-05-14 04:48:37Z

2

Set the Id of your user instance to Guid.NewGuid();

user.Id = Guid.NewGuid();

edited May 14, 2014 at 4:48

marc_s

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answered May 14, 2014 at 1:56

Toan Nguyen

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1 Comment

Fastidious Over a year ago

Same answer I would have suggested. Guid.NewGuid();

qxg · Accepted Answer · 2014-05-15 04:46:27Z

Change your table definition to

[UserCredentialId] UNIQUEIDENTIFIER DEFAULT (NEWSEQUENTIALID()) NOT NULL

Check why prefer NEWSEQUENTIALID than newid at http://technet.microsoft.com/en-us/library/ms189786.aspx.

When a GUID column is used as a row identifier, using NEWSEQUENTIALID can be faster than using the NEWID function. This is because the NEWID function causes random activity and uses fewer cached data pages. Using NEWSEQUENTIALID also helps to completely fill the data and index pages.

Ross Bush · Accepted Answer · 2014-05-14 02:24:51Z

You can have all values in the table default to a new value during insert, much like an IDENTITY.

Run this to set the default of all inserts to use newid().

ALTER TABLE [dbo].[UserCredential] ADD CONSTRAINT [DF_UserCredential_UserCredentialID] DEFAULT (newid()) FOR [UserCredentialId] GO

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