Converting date and/or time from character string is failing - sql

Question

I have this query and I tried converting it to every format, I mean the date time etc but it doesn't work and throws error:
Conversion failed when converting date and/or time from character string.
SELECT W.Organization_ID,
W.NIT_No,
W.SchemeID,
OpeningDate,
OpeningTime,
GETDATE(),
WorkNo,
CONVERT(decimal(10, 2), W.Cost) AS Cost,
WorkName,
W.ExpiryDate as ExpiryDate,
CONVERT(VARCHAR,OpeningDate,106),
CASE WHEN
CONVERT(DATETIME, CONVERT(VARCHAR(20),OpeningDate,106) + ' '
+ CONVERT(VARCHAR(20),OpeningTime,108))< GETDATE()
THEN 1
ELSE 0 END AS OpeningVaild
FROM Works W
the CASE part throws error.
OpeningDate is of type Varchar and OpeningTime is of type Time.
Why?

Answer 1

You are converting just a TIME datatype not a DATETIME so you don't need to specify the style:
DECLARE #T TIME = '08:05:06';
SELECT CONVERT(VARCHAR(8), #T) AS [Time];
SELECT CAST(#T AS VARCHAR(8)) AS [Time];
Or since you are using CONVERT()pick the right style for TIME datatype which is 108 or 114, instead of 106
SELECT CONVERT(VARCHAR(8), #T, 108) AS [Time];
Update:
According to the error Msg, your problem is in the CASE part.
That because you are trying to concat a DATETIME with a VARCHAR datatype, look at here to what you'r converting:
CASE WHEN
CONVERT(DATETIME, CONVERT(VARCHAR(20),OpeningDate,106) + ' '
+ CONVERT(VARCHAR(20),OpeningTime,108))< GETDATE()
THEN 1
ELSE 0 END AS OpeningVaild
Also the column OpeningDate -according to the error Msg- is VARCHAR so your are convert a VARCHAR to VARCHAR then convert it again to DATETIME then you try to concatinate the DATETIME with the VARCHAR returned from converting OpeningTime column from TIMEto VARCHAR, then try to compare them with GETDATE() which is DATETIME datatype.
So you CASE should look like:
CASE WHEN
(
CAST(OpeningDate AS DATETIME) + -- VARCHAR to DATETIME
CAST(OpeningTime AS DATETIME) -- TIME to DATETIME
) < GETDATE()
THEN 1
ELSE 0 END AS OpeningVaild
A beside note, here in this line
CONVERT(VARCHAR,OpeningDate,106),
You are trying to convert a VARCHAR to VARCHAR and without specify the lenght too, so this line should be:
CONVERT(VARCHAR(10),CAST(OpeningDate AS DATE),106),
Finally, don't ever ever store DATE as VARCHAR, the DATE/ TIME/ DATEIME are there for a reason, so use them and all other datatypes wisely.
Here is a demo represent your issue, and how to fix it.

Answer 2

You can simplify this big time by changing the expression a little.
This way you don't have to convert and concatenate.
SELECT
CASE WHEN OpeningDate < GETDATE() - OpeningTime
THEN 1
ELSE 0 END AS OpeningVaild
Note I am assuming that Openingdate has the format dd-mon-yyyy. Otherwise you still need to convert it, but still shorter:
SELECT
CASE WHEN Convert(date, OpeningDate, 106) < GETDATE() - OpeningTime
THEN 1
ELSE 0 END AS OpeningVaild

Answer 3

So I understand the problem is with this part:
CASE WHEN CONVERT(DATETIME, CONVERT(VARCHAR(20),OpeningDate,106) + ' ' + CONVERT(VARCHAR(20),OpeningTime,108))< GETDATE() THEN 1 ELSE 0 END AS OpeningVaild
Update
Since I've first posted my answer it turns out that you store the opening date as varchar instead of date.
First, you should stop doing that. Never store dates in anything other than a Date column (unless you need them with time as well, and then use DateTime2).
For more information, read Aaron Bertrand's Bad habits to kick : choosing the wrong data type.
Assuming the data type of the column can't change, you wrote in the comments to the question:
#ZoharPeled: this is the format of openingdate 2017-04-10
Illustrating one of the problems caused by storing dates as strings - How can I, or anyone else for that matter, know if that's the 10th of April or the 4th of October? The answer is we can't.
So, assuming it's the 10th of April, you can convert it to DateTime using convert with 126 as the style parameter:
CASE
WHEN CONVERT(DateTime, OpeningDate, 126) + CAST(OpeningTime As DateTime) < GETDATE() THEN
1
ELSE
0
END As OpeningVaild
First version:
Assuming that the data type of OpeningDate is Date and the data type of OpeningTime is Time, Seems like you are attempting to figure out if these columns combination into a DateTime is before the current DateTime.
Instead of converting them into strings and back to DateTime, you can cast both to DateTime and simply add them together:
CASE
WHEN CAST(OpeningDate As DateTime) + CAST(OpeningTime As DateTime) < GETDATE() THEN
1
ELSE
0
END As OpeningVaild
Another option would be to use GETDATE() twice. I don't think it should matter in the select clause, but in the where clause it's important to use this option since the first one will make these columns non-seargable, meaning the database engine will not be able to use any indexes that might help the execution plan of the statement:
CASE
WHEN OpeningDate < CAST(GETDATE() AS DATE)
OR
(
OpeningDate = CAST(GETDATE() AS DATE)
AND OpeningTime <= CAST(GETDATE() AS TIME)
) THEN
1
ELSE
0
END AS OpeningVaild
That being said, your query also have CONVERT(VARCHAR,OpeningDate,106) - The 106 style returns a string representation of the date as dd mon yyyy - meaning 11 chars - so change that to CONVERT(CHAR(11),OpeningDate,106) Note that using varchar without specifying the length defaults to 30, which is not a problem in this case since it's more than he 11 chars you need, but it's a bad habit to not specify length and you should kick it.