存储过程的问题，小问题，帮着看看！！！

[luhaiyan]

1. USE football
2. GO
3. IF EXISTS(SELECT name FROM sysobjects4.
4. WHERE name = 'InsertCustomerInfomation' AND type = 'P')
5. DROP PROCEDURE InsertCustomerInfomation
6. GO
7. USE football
8. GO
9. CREATE PROCEDURE InsertCustomerInformation
10. @Customer_name varchar(20),
11. @Money_type char(5),
12. @MobileTel varchar(20),
13. @Telephone varchar(20),
14. @Note varchar(300),
15. @MaxCustomer_id int output
16. AS

17. SELECT @MaxCustomer_id = max(Customer_id) + 1 FROM CustomerInformation
18. if @MaxCustomer_id = 0
19. @MaxCustomer_id = MaxCustomer_id + 1
20. INSERT INTO CustomerInformation
21. (Customer_id,Customer_name,Money_type,MobileTel,Telephone,Note)
22. VALUES(@MaxCustomer_id,
23. @Customer_name,
24. @Money_type,
25. @MobileTel,
26. @Telephone,
27. @Note)
28. GO

执行后提示：
Server: Msg 170, Level 15, State 1, Procedure InsertCustomerInformation, Line 18
Line 18: Incorrect syntax near '@MaxCustomer_id'.

可能是第18行出错了。
怎么办呢？

[pengdali]

17. SELECT @MaxCustomer_id = max(Customer_id) + 1 FROM CustomerInformation
18. if @MaxCustomer_id = 0
19. set @MaxCustomer_id = MaxCustomer_id + 1

[pengdali]

19. set @MaxCustomer_id = 1

[txlicenhe]

18. if @MaxCustomer_id = 0
19. set @MaxCustomer_id = MaxCustomer_id + 1

[txlicenhe]

18. if @MaxCustomer_id = 0
19. set @MaxCustomer_id = @MaxCustomer_id + 1
或
19. set @MaxCustomer_id = 1