Unfamiliar SQL Syntax in a Scripted-Out table script-CodePudding

I've jut recently scripted out a table from an existing DB on one of our SQL Servers, which brings back the following glorious result:

SET ANSI_NULLS ON
GO

SET QUOTED_IDENTIFIER ON
GO

CREATE TABLE [dbo].[queuemembership](
    [Id] [uniqueidentifier] NOT NULL,
    [versionnumber] [bigint] NULL,
    [queueid] [uniqueidentifier] NULL,
    [queuemembershipid] [uniqueidentifier] NULL,
    [systemuserid] [uniqueidentifier] NULL,
 CONSTRAINT [EPK[dbo]].[queuemembership]]] PRIMARY KEY CLUSTERED 
(
    [Id] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]
GO

I'm not familiar with the EPK bit of CONSTRAINT [EPK[dbo]].[queuemembership]]] PRIMARY KEY CLUSTERED

If I recreate the table from scratch I can replace EPK with other text, which makes me think this is some sort of external metadata or something.

Can anyone shed any light on this?

CodePudding user response：

I've covered this in the comments, but to put it into an answer, [EPK[dbo]].[queuemembership]]] is a delimit identified and properly escaped value for an object (specifically a CONSTRAINT) called EPK[dbo].[queuemembership].

This is, in truth, a very poorly named object; it contains multiple different characters that require the name to need to be delimit identified and a multiple characters that need escaping. Any of the right brackets (]) need escaping, in the same way that you would a single quote (') in a literal string; double them up. Then, because of the said right brackets, as well as the left brackets ([) and the periods (.), which is a part separator, this means that the entire value needs to be delimit identified.

As a result, you end up with that value [EPK[dbo]].[queuemembership]]]. You can also double check this by running PRINT QUOTENAME(N'EPK[dbo].[queuemembership]');.

Honestly, I suggest naming you CONSTRAINT something better, that doesn't need delimit identification or escaping. PK_queuemembership is likely more than fine.