如何在sql server中生成自动插入功能SEAT_NO，如A1，A2 .... B1，B2

Question

＆GT;我创建了以下函数来获得类似a1，a2 ..... a12，＆gt;的输出。 B1，B2 ..... B12，C1 ...... Z12。

 Create function Fun_Auto_Insert()
returns nchar(3)
as
BEGIN 
    DECLARE @Seat_No NCHAR(3) = 'A1' 
    declare @Name CHAR(30) 
    declare @Contact_No INT 
    declare @Row_No INT 
    declare @Row_ID CHAR(1) 
    declare @ASCII_No INT 
    declare @CHAR_ID CHAR 

IF (SELECT count(*) FROM MOVIE_TICKETS) = 0 
    BEGIN 
        RETURN @Seat_No 
    END 
ELSE 
    SELECT @Seat_No= MAX(SEAT_NO) FROM MOVIE_TICKETS 

    SELECT @Row_No=SUBSTRING( @Seat_No,2,LEN(@Seat_No)-1) FROM MOVIE_TICKETS 

IF @Row_No=12 
    BEGIN 
        SET @Row_ID=SUBSTRING(@Seat_No,1,1) 
        --convert to ASCII NO 
        SET @ASCII_No=ASCII(@Row_ID) 
        SET @ASCII_No=@ASCII_No+1 
        --convert to CHAR 
        SET @CHAR_ID=CHAR(@ASCII_No) 
        SET @Row_No=1 
        SET @Seat_No=CONCAT(@CHAR_ID,@Row_No) 
        RETURN @Seat_No 
    END 
ELSE 
    SET @Row_No=@Row_No+1 

SET @Row_ID=SUBSTRING(@Seat_No,1,1) 
SET @Seat_No=CONCAT(@Row_ID,@Row_No) 

RETURN @Seat_No 

END 

GO

但不幸的是我的逻辑失败了。它在A10之后显示SEAT_NO A10，如下所示。但是在A10之后我想要A11。

任何人都可以帮助我获得我想要的输出a1，a2 ..... a12，b1，b2 ..... b12，c1 ...... z12。

SEAT_NO CONTACT_NO  NAME
A1      8444        BHARATH
A2      8444        BHARATH
A3      8444        BHARATH
A4      8444        BHARATH
A5      8444        BHARATH
A6      8444        BHARATH
A7      8444        BHARATH
A8      8444        BHARATH
A9      8444        BHARATH
A10     8444        BHARATH
A10     8444        BHARATH
A10     8444        BHARATH
A10     8444        BHARATH
A10     8444        BHARATH

Answer 1

我会重写整个函数并废弃所有这些字符串操作，见下文：

功能定义

Create function Fun_Auto_Insert()
returns nchar(3)
as
BEGIN 
    DECLARE @Seat_No NCHAR(3);

;WITH CTE AS 
(SELECT Alphas+vals AS SEAT_NO
      ,Alphas 
      ,vals  
FROM (
    select CHAR(number) Alphas
    from master..spt_values
    WHERE number >= 65 and number <= 90
    GROUP BY number) A
              CROSS APPLY (VALUES ('1'),('2'),('3'),('4')
                                 ,('5'),('6'),('7'),('8')
                                 ,('9'),('10'),('11'),('12'))C(vals)
)
SELECT TOP 1 @Seat_No = SEAT_NO
FROM CTE C
WHERE NOT EXISTS (SELECT 1 
                  FROM MOVIE_TICKETS
                  WHERE C.SEAT_NO = Seat_No)
ORDER BY  Alphas ASC , CAST(vals AS INT) ASC

   RETURN @Seat_No; 
END 
GO

测试

CREATE TABLE MOVIE_TICKETS(Seat_No VARCHAR(3))
GO
INSERT INTO MOVIE_TICKETS VALUES ('A2'), ('A10'), ('B2')
GO

SELECT dbo.Fun_Auto_Insert()
GO

结果

A1