How to Fix the datetime Conversion Error in SQL Server

Learn how to resolve the datetime conversion error in SQL Server with easy-to-follow steps and code examples.
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How to Fix the datetime Conversion Error in SQL Server

When working with SQL Server, you might encounter a common error related to datetime conversions. This issue can be quite frustrating, especially when it disrupts your workflow and prevents your queries from executing successfully. In this guide, we will explore this problem in detail and provide a clear, step-by-step solution.

The Problem

Imagine the following scenario where a SQL Server user attempts to calculate the number of days between two dates. They use the DATEDIFF function combined with the CONVERT function, as shown in the code below:

[[See Video to Reveal this Text or Code Snippet]]

Upon running this code, they encounter the following error message:

[[See Video to Reveal this Text or Code Snippet]]

This error is a result of incorrect usage of the CONVERT function with the wrong data type, resulting in the failure to convert the date and/or time from the character string format.

The Solution

To fix this conversion error, we need to ensure that we are using the correct datatype in the CONVERT function. Instead of converting to VARCHAR, we should convert the date strings directly to the date data type. Let’s break this down step by step.

Step 1: Modify the Conversion

Change the conversion of the date strings from VARCHAR to date. Update your SQL code as follows:

[[See Video to Reveal this Text or Code Snippet]]

CONVERT(date, '21/02/2021', 103): This line converts the string '21/02/2021' to the date type, using style 103 which specifies the British/French date format (dd/mm/yyyy).

DATEDIFF(day, ...): This function calculates the difference in days between the two date values.

Step 2: Executing the Corrected Query

Now, when you execute the corrected SQL code above, SQL Server will successfully perform the conversion and return the desired count of days between the two dates without any errors.

Example Result

After running the corrected SQL command, you can expect to see an output similar to:

[[See Video to Reveal this Text or Code Snippet]]

This indicates that there is 1 day difference between the two dates you provided.

Conclusion

In SQL Server, when working with date and time conversions, always ensure that you are using the correct data type to avoid conversion errors. The solution to the datetime conversion error involves using date instead of varchar in the CONVERT function, allowing for successful execution of your queries.

Following this guide should help you overcome the frustrating datetime conversion errors in SQL Server and enhance your overall database management experience.