我需要一个SQLserver代码，自动生成单据编码

当然，我可以为您提供一个SQL Server代码，用于自动生成单据编码。以下是示例代码：

CREATE PROCEDURE [dbo].[GenerateDocumentCode]
@DocumentType VARCHAR(50),
@DocumentCode VARCHAR(50) OUTPUT
AS
BEGIN
DECLARE @Prefix VARCHAR(10)
DECLARE @Suffix VARCHAR(10)
DECLARE @Counter INT

SET @Prefix = LEFT(@DocumentType, 3)
SET @Suffix = RIGHT(@DocumentType, 3)

SELECT @Counter = ISNULL(MAX(CAST(RIGHT(DocumentCode, 6) AS INT)), 0) + 1
FROM dbo.Documents
WHERE LEFT(DocumentCode, 3) = @Prefix AND RIGHT(DocumentCode, 3) = @Suffix

SET @DocumentCode = @Prefix + RIGHT('000000' + CAST(@Counter AS VARCHAR(6)), 6) + @Suffix
END

请注意，此代码仅供参考，您需要根据您的具体需求进行修改。