Question

我有一个查询，我必须比较到期日，而且我似乎无法使CASE表达式正常工作。

此刻，我已经注释掉了原来的ELSE子句，我认为可以解决这个问题，但是不幸的是，它给了我一个错误“函数CASE的参数1无效。原因...：数据指定的函数CASE的参数1的类型，长度或值无效。“

有什么想法吗？我正在使用IBM DB2。

ELSE子句的理想结果是将发票日期（AHINVD）和发票到期日期代码（CMDDCD）相加以获得原始发票到期日期。

    Select
CMCMP as CompanyCode
,CMCUS# as CustomerCode
,CMNAME as CustomerName
,CMDDCD as InvoiceDuteDateCode
,AHINV# as InvoiceNumber
,AHISEQ as InvoiceSequence
,AHINVD as InvoiceDate
,AHDUED as InvoiceDueDate
,case
    when date(to_date(RTRIM(AHINVD),'YYYYMMDD')) + cast(CMDDCD as INT) days = date(to_date(RTRIM(AHDUED),'YYYYMMDD')) then NULL
    --else date(to_date(RTRIM(AHINVD),'YYYYMMDD')) + cast(CMDDCD as INT) days
    else '12'
end as OriginalInvoiceDueDate
,AHAMT$ as OriginalAmount
,AHCURC as CurrencyCode
from WSDATARG.CUSMASFL cm
left join WSDATARG.ARIHDRFL ar
on CMCMP = AHCMP
and CMCUS# = AHCUS#
where CMCMP = '14'
and AHINVD > '20180918

Answer 1

尝试CAST(NULL AS DATE)而不是NULL

DB2: Won't Allow "NULL" column?

Answer 2

我怀疑您正在使用DB2 for z / OS或DB2 for i。如果是这样，我怀疑它不会喜欢未键入的NULL。 Db2 LUW将进行锻炼，它必须是DATE。例如

db2 "CREATE TABLE TEST(AHINVD CHAR(8), CMDDCD CHAR(6), AHDUED CHAR(8))"
db2 "describe 
SELECT 
case
    when date(to_date(RTRIM(AHINVD),'YYYYMMDD')) + cast(CMDDCD as INT) days = date(to_date(RTRIM(AHDUED),'YYYYMMDD')) then NULL
    else date(to_date(RTRIM(AHINVD),'YYYYMMDD')) + cast(CMDDCD as INT) days
end
FROM TEST"


 Column Information

 Number of columns: 1

 SQL type              Type length  Column name                     Name length
 --------------------  -----------  ------------------------------  -----------
 385   DATE                     10  1                                         1

但例如这个

SELECT 
case
    when date(to_date(RTRIM(AHINVD),'YYYYMMDD')) + cast(CMDDCD as INT) days = date(to_date(RTRIM(AHDUED),'YYYYMMDD')) then CAST(NULL AS DOUBLE)
    else date(to_date(RTRIM(AHINVD),'YYYYMMDD')) + cast(CMDDCD as INT) days
end
FROM TEST

返回

‬‪The‬‎ ‪data‬‎ ‪types‬‎ ‪of‬‎ ‪the‬‎ ‪result‬‎-‪expressions‬‎ ‪of‬‎ ‪a‬‎ ‪CASE‬‎ ‪expression‬‎ ‪or‬‎ ‪DECODE‬‎ ‪function‬‎ ‪are‬‎ ‪not‬‎ ‪compatible‬‎.‪‬‎.‪‬‎ ‪SQLCODE‬‎=‪‬‎-‪581‬‎,‪‬‎ ‪SQLSTATE‬‎=‪42804‬‎

我猜这与您的Db2 for z / OS消息类似

也许，因为如果您没有ELSE，则会得到NULL，为什么不直接编写此代码呢？

SELECT 
case
    when  date(to_date(RTRIM(AHINVD),'YYYYMMDD')) + cast(CMDDCD as INT) days 
       <> date(to_date(RTRIM(AHDUED),'YYYYMMDD'))
    then  date(to_date(RTRIM(AHINVD),'YYYYMMDD')) + cast(CMDDCD as INT) days
end
FROM TEST

SQL CASE表达式通过计算给出错误消息

2 个答案: