CREATE TABLE CocoJambo (
Id CHAR(12) NOT NULL,
Value INT NULL,
CHECK( Id LIKE '[0-9][0-9][0-9][0-9][A-Z][0-9][0-9][0-9][0-9][0-9][0-9][0-9]' )
);
GO
CREATE UNIQUE INDEX IUN_CocoJambo_Id
ON CocoJambo (Id);
GO
INSERT CocoJambo (Id, Value)
SELECT '1001P0010001', 100
UNION ALL SELECT '1001P0010002', 200
UNION ALL SELECT '1001P0010003', 300
UNION ALL SELECT '1001P0010004', 400
UNION ALL SELECT '1001P0020001', 100
UNION ALL SELECT '1001P0020002', 200
UNION ALL SELECT '1001P0020003', 300
UNION ALL SELECT '1001P0020004', 400;
GO
-- Test 1: generating a single Id
DECLARE @Prefix CHAR(5),
@Sufix CHAR(4);
SELECT @Prefix = '1001P',
@Sufix = '0001';
BEGIN TRAN
DECLARE @LastGeneratedMiddleValue INT,
@LastValue INT;
SELECT @LastGeneratedMiddleValue = y.MiddleValue,
@LastValue = y.Value
FROM
(
SELECT x.MiddleValue, x.Value,
ROW_NUMBER() OVER(ORDER BY x.MiddleValue DESC) AS RowNum
FROM
(
SELECT CONVERT(INT,SUBSTRING(a.Id,6,3)) AS MiddleValue, a.Value
FROM CocoJambo a WITH(UPDLOCK) -- It will lock the rows (U lock) during transaction
WHERE a.Id LIKE @Prefix+'%'+@Sufix
) x
) y
WHERE y.RowNum=1;
SELECT @LastGeneratedMiddleValue = ISNULL(@LastGeneratedMiddleValue ,0)
SELECT @Prefix
+RIGHT('00'+CONVERT(VARCHAR(3),@LastGeneratedMiddleValue +1),3)
+@Sufix AS MyNewId,
@LastValue AS Value
COMMIT TRAN;
GO
-- Test 2: generating many Id's
BEGIN TRAN
DECLARE @Results TABLE (
Prefix CHAR(5) NOT NULL,
Sufix CHAR(4) NOT NULL,
LastGeneratedMiddleValue INT NOT NULL,
LastValue INT NULL
);
INSERT @Results (Prefix, Sufix, LastGeneratedMiddleValue, LastValue)
SELECT y.Prefix, y.Sufix, y.MiddleValue, y.Value
FROM
(
SELECT x.Prefix, x.MiddleValue, x.Sufix, x.Value,
ROW_NUMBER() OVER(PARTITION BY x.Prefix, x.Sufix ORDER BY x.MiddleValue DESC) AS RowNum
FROM
(
SELECT SUBSTRING(a.Id,1,5) AS Prefix,
CONVERT(INT,SUBSTRING(a.Id,6,3)) AS MiddleValue,
SUBSTRING(a.Id,9,4) AS Sufix,
a.Value
FROM CocoJambo a WITH(UPDLOCK) -- It will lock the rows (U lock) during transaction
) x
) y
WHERE y.RowNum=1;
SELECT r.*,
r.Prefix
+RIGHT('00'+CONVERT(VARCHAR(3),r.LastGeneratedMiddleValue +1),3)
+r.Sufix AS MyNewId,
r.LastValue AS Value
FROM @Results r;
COMMIT TRAN;
GO