String was not recognized as a valid DateTime

Hi Ramco Ramco,

If you using SQL to upload your Excel data in database (SQL Server 2019 in my case but other database is possible), you can convert directly your datetime with TSQL. I propose this snippet code :

using System.Collections.Generic;
using System;
using System.Data;

//List of Anonymous type with your datas
var list = new[]
{
    new {MentorID="1422",Date="04-19-2023",StartTime="2023-04-19 11:00:00"},
    new {MentorID="1422",Date="04/21/2023",StartTime="2023-04-21 11:00:00"},
};

string maskSelection = string.Empty;
string US_Style = "101"; //U.S. style for SQL Server with mask mm/dd/yyyy
string USA_Style = "110"; //U.S.A. style for SQL Server with mask mm-dd-yyyy

foreach (var o in list)
{
    //Select sql convert style
    maskSelection = o.Date.Contains("-") ? USA_Style : US_Style;
    //Generate Insert
    string insertSQL = $"INSERT INTO [dbo].[Table_1]([Date]) VALUES (convert(datetime, {o.Date}, {maskSelection}));";
    Console.WriteLine(insertSQL);
}

This code generate, in this case, INSERT script for update your SQL Server 2019 Database. This is console output :

INSERT INTO [dbo].[Table_1]([Date]) VALUES (convert(datetime, 04-19-2023, 110));
INSERT INTO [dbo].[Table_1]([Date]) VALUES (convert(datetime, 04/21/2023, 101));

 The result in SQL Server 2019 (Date column is type of datetime) is visible in attached zip file.

I hope to help you.

Hi

  I agree with all but show about 40 got uploaded & other not out of 90.

All the coloumns have same type of Date Format.

Thanks

The error you are receiving is likely because the format of the date in your Excel file is not in a format that can be converted to a DateTime object using the Convert.ToDateTime() method.

In your example, you have two different date formats in your Excel file - "04-19-2023" and "04/21/2023". The Convert.ToDateTime() method expects the date to be in a specific format, such as "MM/dd/yyyy" or "dd-MM-yyyy". If the date format in the Excel file does not match the expected format, an exception will be thrown.

To avoid this error, you can either change the format of the date in your Excel file to match the expected format, or you can use a different method to convert the string to a DateTime object that allows you to specify the format of the input string.

Here's an example of how you can use the DateTime.TryParseExact() method to convert a string to a DateTime object with a specific format:

string dateString = "04-19-2023";
DateTime dateValue;

if (DateTime.TryParseExact(dateString, "MM-dd-yyyy", CultureInfo.InvariantCulture, DateTimeStyles.None, out dateValue))
{
    // Conversion succeeded
    // Do something with dateValue
}
else
{
    // Conversion failed
    // Handle error
}

In this example, the DateTime.TryParseExact() method attempts to convert the string "04-19-2023" to a DateTime object using the "MM-dd-yyyy" format. If the conversion succeeds, the DateTime object is stored in the dateValue variable. If the conversion fails, an error can be handled in the else block.

You can modify this code to fit your specific scenario and use it to convert the date strings from your Excel file to DateTime objects.

It seems that the error is occurring because the format of the date values in your Excel file is not consistent with the format expected by the Convert.ToDateTime method.

You can try using the DateTime.ParseExact or DateTime.TryParseExact method to convert the date string to a DateTime object, specifying the exact format of the date string.

string dateString = "04-19-2023";
DateTime startDate;

if (DateTime.TryParseExact(dateString, "MM-dd-yyyy", CultureInfo.InvariantCulture, DateTimeStyles.None, out startDate))
{
    // conversion succeeded, startDate contains the parsed date value
}
else
{
    // conversion failed
}

we are using DateTime.TryParseExact to try and parse the dateString variable using the format "MM-dd-yyyy". If the conversion succeeds, the parsed date value will be stored in the startDate variable. If the conversion fails, an exception will not be thrown, but you can handle the failure using an else block.

Can you tell us the exact data that is producing the error? The following fiddle does not get an error therefore I do not know what the data is that is causing the problem.

https://dotnetfiddle.net/YPSpL1

The error you are seeing is likely due to an incorrect format used in the Convert.ToDateTime method. When parsing a string to a DateTime object, the format of the string must match the format of the DateTime object.

In your case, you are trying to convert a string to a DateTime object, but the format of the string is not matching the expected format of the DateTime object.

Based on your data, it looks like you have two different date formats: "MM-dd-yyyy" (e.g. "04-19-2023") and "MM/dd/yyyy" (e.g. "04/21/2023"). The error message indicates that the format of the string being passed to Convert.ToDateTime does not match the expected format.

To fix the issue, you can try using the DateTime.ParseExact method instead of Convert.ToDateTime. DateTime.ParseExact allows you to specify the exact format of the string you are trying to parse, which can help avoid errors due to different date formats.

Here's an example of how you can use DateTime.ParseExact to parse the date string in the "MM-dd-yyyy" format:

string dateString = "04-19-2023";
DateTime date = DateTime.ParseExact(dateString, "MM-dd-yyyy", CultureInfo.InvariantCulture);

And here's an example of how you can use DateTime.ParseExact to parse the date string in the "MM/dd/yyyy" format:

string dateString = "04/21/2023";
DateTime date = DateTime.ParseExact(dateString, "MM/dd/yyyy", CultureInfo.InvariantCulture);

====================================

If you want to make the date format consistent across all rows in your Excel file, you can use Excel's built-in formatting options to convert all the dates to the same format.

To do this, follow these steps:

1. Select the cells containing the dates you want to convert.

2. Right-click on the selected cells and choose "Format Cells" from the context menu.

3. In the "Format Cells" dialog box, select the "Custom" category.

4. In the "Type" field, enter a custom date format that will work for all your dates. For example, you can use "yyyy-MM-dd" to format dates as "2023-04-19".

5. Click "OK" to apply the new format to the selected cells.

Once you have converted all the dates to the same format, you can use the same method to parse the dates in your C# code. For example, if you have converted all the dates to the "yyyy-MM-dd" format, you can use the following code to parse them:

string dateString = "2023-04-19";
DateTime date = DateTime.ParseExact(dateString, "yyyy-MM-dd", CultureInfo.InvariantCulture);

Thanks