Conversion failed when converting date and/or time from character string

Question

I have this query :

set IDENTITY_INSERT dbo.OtherData1 ON


INSERT INTO OtherData1 (OtherDataID, EmployeeID, OtherDate, OType, OSubject, StatementNo, Stateme         


        

Answer 1

ISDATE won't work since you cannot even specify a date format as you can with CONVERT. The following is a VERY elaborate test to reformat valid dates into YYYYMMDD for which ISDATE works predictably.

with otherdata(StatementDate) as (
select convert(varchar(10),'1/10/2011') union all
select '28/2/2911' union all
select '8/12/2011' union all
select '13/13/2011' union all
select '13/12/2011' union all
select '12/13/2011' union all
select '2/29/2011' union all
select '29/2/2011' union all
select '29/2/2012' union all
select '2011-02-01' union all
select '1/1/11' union all
select '1/1/99' union all
select '' union all
select null)

-- THE QUERY YOU NEED is below this line. The above virtually sets up a table
-- without having to physically create it
select
    statementdate,
    YYYYMMDDToTest,
    ISDate(YYYYMMDDToTest)
from otherdata
cross apply
       (
       select TheYear = case
       when not statementdate like '%[0-9]/%[0-9]/%[0-9][0-9]' then null
       when convert(int,replace(statementdate,'/','')) != replace(statementdate,'/','') then null
       when statementdate like '%[0-9]/%[0-9]/[0-9][0-9]' then
           case when RIGHT(statementdate,2) >=50
           then '19'+RIGHT(statementdate,2)
           else '20'+RIGHT(statementdate,2)
           end
       when statementdate like '%[0-9]/%[0-9]/[1-9][0-9][0-9][0-9]' then
           RIGHT(statementdate,4)
       end
       ) A
cross apply
       (
       select YYYYMMDDToTest = case
       when TheYear is not null then
           TheYear
           + -- month
           right(100+SUBSTRING(statementdate, charindex('/',statementdate) +1,
           charindex('/',statementdate,charindex('/',statementdate)+1)-
           charindex('/',statementdate)-1),2)
           + -- day
           right(100+LEFT(statementdate, charindex('/', StatementDate) -1),2)
       end
       ) B
WHERE ISDate(YYYYMMDDToTest) = 0

Comment out the last line WHERE ISDate(YYYYMMDDToTest) = 0 to see what it does with each date.

---

EDIT

You can turn this into a function that replaces the ISDATE - but for the SPECIFIC format [d]d/[m]m/yyyy.

create function dbo.superIs103Date(@any varchar(50))
returns bit as begin
declare @theyear varchar(10)
set @TheYear = case
       when not @any like '%[0-9]/%[0-9]/%[0-9][0-9]' then null
       when convert(int,replace(@any,'/','')) != replace(@any,'/','') then null
       when @any like '%[0-9]/%[0-9]/[0-9][0-9]' then
           case when RIGHT(@any,2) >=50
           then '19'+RIGHT(@any,2)
           else '20'+RIGHT(@any,2)
           end
       when @any like '%[0-9]/%[0-9]/[1-9][0-9][0-9][0-9]' then
           RIGHT(@any,4)
       end
declare @YYYYMMDDToTest varchar(50)
set @YYYYMMDDToTest = case
       when @TheYear is not null then
           @TheYear
           + -- month
           right(100+SUBSTRING(@any, charindex('/',@any) +1,
           charindex('/',@any,charindex('/',@any)+1)-
           charindex('/',@any)-1),2)
           + -- day
           right(100+LEFT(@any, charindex('/', @any) -1),2)
       end
return ISDate(@YYYYMMDDToTest)
end
GO

-- example usage
select dbo.superIs103Date('33/1/1700')
-- returns 0