4ZW6tG6j

1CREATE TABLE dbo.Seqs(
2    SequenceKey nvarchar(10) NOT NULL,
3    UsageSequence smallint NOT NULL,
4    col1 bit NOT NULL,
5    col2 nvarchar(30) NULL,
6    CONSTRAINT PK_Seqs PRIMARY KEY CLUSTERED 
7    (
8        SequenceKey ASC,
9        UsageSequence ASC
10    )
11) 
12     
13CREATE TABLE dbo.Sometbl (
14    SomeID int IDENTITY(1,1) NOT NULL,
15    Col1 int NOT NULL,
16    Col2 nvarchar(100) NOT NULL,
17    Col3 nvarchar(30) NULL,
18    SequenceKey nvarchar(10) NOT NULL,
19    CONSTRAINT PK_Sometbl PRIMARY KEY CLUSTERED (
20        SomeID ASC
21        )
22    ) 
23     
24CREATE FUNCTION dbo.CheckSequenceKey (@SequenceKey nvarchar(10))
25RETURNS bit
26AS 
27BEGIN
28  DECLARE @retval bit
29
30  IF EXISTS (SELECT 1 FROM dbo.Seqs S WHERE S.SequenceKey = @SequenceKey)
31      SET @retval = 1
32  ELSE 
33      SET @retval = 0
34
35  RETURN @retval
36END;
37GO
38
39ALTER TABLE dbo.Sometbl
40  ADD CONSTRAINT chkSequenceKey
41  CHECK (dbo.CheckSequenceKey(SequenceKey) = 1);