Question

将varchar值'，'转换为数据类型int时转换失败。

update Quotation_T  set DOID= CASE 

              WHEN DOID IS NULL THEN CAST(2 AS NVARCHAR(20))
              WHEN DOID LIKE '%'+CAST(2 AS NVARCHAR(20))+'%' THEN DOID       
              WHEN DOID IS NOT NULL THEN (DOID +','+CAST(2 AS NVARCHAR(20)))
           END  
         where Quotation_T.QuotationID = 2 and Br_Code=1 and Item_Code=705

Answer 1

You must convert DIOD to NVARCHAR in last when block.

update Quotation_T  set DOID= CASE     
                  WHEN DOID IS NULL THEN CAST(2 AS NVARCHAR(20))
                  WHEN DOID LIKE '%'+CAST(2 AS NVARCHAR(20))+'%' THEN CAST(DOID AS NVARCHAR(20))
                  WHEN DOID IS NOT NULL THEN (CAST(DOID AS NVARCHAR(20)) +','+CAST(2 AS NVARCHAR(20)))
                   END  
    where Quotation_T.QuotationID = 2 and Br_Code=1 and Item_Code=705

Answer 2

I believe your DOID data type is int, and needs to be NVARCHAR(20) - (maybe NVARCHAR(max) would be better) to support characters. Your update works fine if the DOID is NVARCHAR(20).

Here's what I see from testing.

create table Quotation_T
(
DOID nvarchar(20)
)

insert into Quotation_T VALUES(N'hello');
insert into Quotation_T VALUES(null);
insert into Quotation_T VALUES(N'2')

update Quotation_T  set DOID= CASE 
    WHEN DOID IS NULL THEN CAST(2 AS NVARCHAR(20))
    WHEN DOID LIKE '%'+CAST(2 AS NVARCHAR(20))+'%' THEN DOID       
    WHEN DOID IS NOT NULL THEN (DOID +','+CAST(2 AS NVARCHAR(20)))
END  

SELECT * from Quotation_T
/* results in
hello,2
2
2
*/

create table Quotation_Tint
(
DOID int
)

insert into Quotation_Tint VALUES(4);
insert into Quotation_Tint VALUES(null);
insert into Quotation_Tint VALUES(2)

update Quotation_Tint  set DOID= CASE 
    WHEN DOID IS NULL THEN CAST(2 AS NVARCHAR(20))
    WHEN DOID LIKE '%'+CAST(2 AS NVARCHAR(20))+'%' THEN DOID       
    WHEN DOID IS NOT NULL THEN (DOID +','+CAST(2 AS NVARCHAR(20)))
END  

SELECT * from Quotation_Tint
/* results in 
Conversion failed when converting the varchar value ',' to data type int.
*/

将varchar值'，'转换为数据类型int时转换失败

2 个答案: