Conversion Failed When Converting Datetime From Character String When Using Where Clause

I have written the following query to extract data splitting a text string into separate fields. This query works fine and returns results.



WITH a (company_id, user_id, project_id, customer_id, action, importdate, groupid, accountnumber, amount, notes, created, updated) AS

(

select

company_id,

user_id,

project_id,

customer_id,

action,

CAST(SUBSTRING(params, PATINDEX('%[ImportDate=%', params)+13, 19) AS datetime) AS ImportDate,

SUBSTRING(params, PATINDEX('%GroupID=%', params)+8, 1) AS GroupID,

SUBSTRING(params, PATINDEX('%AccountNo=%', params)+10, 7) AS AccountNumber,

CAST(SUBSTRING(substring(params, 0, len(params)), PATINDEX('%Amount=%', params)+7, 10) AS decimal(18,2)) AS Amount,

notes,

created,

updated

from


database.dbo.tablename

where

customer_id is not null and

PATINDEX('%GroupID=%', params) <> 0 and

PATINDEX('%ImportDate=%', params) <> 0 and

PATINDEX('%AccountNo=%', params) <> 0 and

PATINDEX('%Amount=%', params) <> 0

)

select

company_id,

user_id,

project_id,

customer_id,

action,

importdate,

DATEPART(year, importdate) AS importyear,

DATEPART(month, importdate) AS importmonth,

groupid,

accountnumber,

amount,

notes,

created,

updated

from

a




The problem arises when I try to do a WHERE on either the importyear or importmonth field.



WITH a (company_id, user_id, project_id, customer_id, action, importdate, groupid, accountnumber, amount, notes, created, updated) AS

(

select

company_id,

user_id,

project_id,

customer_id,

action,

CAST(SUBSTRING(params, PATINDEX('%[ImportDate=%', params)+13, 19) AS datetime) AS ImportDate,

SUBSTRING(params, PATINDEX('%GroupID=%', params)+8, 1) AS GroupID,

SUBSTRING(params, PATINDEX('%AccountNo=%', params)+10, 7) AS AccountNumber,

CAST(SUBSTRING(substring(params, 0, len(params)), PATINDEX('%Amount=%', params)+7, 10) AS decimal(18,2)) AS Amount,

notes,

created,

updated

from


database.dbo.tablename

where

customer_id is not null and

PATINDEX('%GroupID=%', params) <> 0 and

PATINDEX('%ImportDate=%', params) <> 0 and

PATINDEX('%AccountNo=%', params) <> 0 and

PATINDEX('%Amount=%', params) <> 0

)

select

company_id,

user_id,

project_id,

customer_id,

action,

importdate,

DATEPART(year, importdate) AS importyear,

DATEPART(month, importdate) AS importmonth,

groupid,

accountnumber,

amount,

notes,

created,

updated

from

a


where DATEPART(year, importdate) = 2007

I get


Conversion failed when converting datetime from character string.

but when I use ISDATE() to validate the importyear it returns nothing indicating that the actual importdate is a valid date. Can anyone help please?

Thanks