Rashmi, we're struggling to understand your question. This is my understanding so far:

• This isn't specific to dates, the query you want to perform could involve any part of the dataset of any type
• You're comfortable creating queries for Dataset expressions, so you're not asking how to select rows that match a given criteria.

Okay, but then you say "I want to remove the rows...", but you already know how to do that with a Query expression. Please explain how removing rows is different than performing a filter Query.

Then you ask "how do I go about it in a dataset without converting it into a database". But that's exactly what you've been doing. And that's exactly what my and Rohit's answers do. When you use the term "dataset", are you referring to a Mathematica Dataset[...] expression? That's what I was assuming, but I'm now thinking that my assumption was wrong. Please explain what you mean by "dataset".

As for "database", are you having difficulty integrating with a database engine like MySQL? If that is the issue, then we can help with that. Please confirm if this is your challenge.

Another possibility that I can think of is that you want to import the csv data, clean it, and then export it back out as csv. Maybe when you say "dataset" you mean "csv file". If that's the case, we can help with that (or you can just look at the documentation for Export). Please confirm if this is your challenge.

Some other thoughts after actually looking at the details of your query. Presumably #Date is expected to be a string. ToCharacterCode will produce a list of character codes corresponding to each character in the string. Length will then give you the length of that list. Thus, you seem to be wanting to filter on string length. There is a function for that: StringLength. So, maybe something like this?

cleanfinal[Select[StringLength[#Date] == 19 &]]

Hello Eric,

Thank you for your quick answer. But my problem is not this particular query. If i were to perform any Select query for example:

cleanfinal[Select[#Date === "String" &], All]

This gives me the result. But i cannot figure out a way to perform deletecases on the dataset. Do i need to convert the dataset into a database anytime i were to perform Queries similar to SQL or any relational database?

Oh, wait. Is this a variable update question? Do you want the variable cleanfinal to be updated with the results of your query? That's easy:

cleanfinal = cleanfinal[Select[StringLength[#Date] == 19 &]]

Hello Rohit, Thank you for your quick answer. I have attached a sample copy of the data. This is a CSV file in which the date column is having different format for a lot of the records, i want to remove the rows where the date is not in the format that can be converted to date object. The problem is not the date format, if I were to perform another operation on a different column where I am required to delete rows which doesn't have the desired form of value, how do I go about it in a dataset without converting it into a database. For example, for any column that contains special characters, or contains space, etc. Thanks.

Attachments:

sample.csv

If

cleanfinal[Select[Length[ToCharacterCode[#Date]] != 19 &], All]

gave you the result to be removed, then just negate the select condition:

cleanfinal[Select[Length[ToCharacterCode[#Date]] == 19 &], All]

Also, the All is probably superfluous. I haven't actually tested this query, because I don't know what your data is, so don't actually know if this works as you want.