How to Concat and Create a Date from Strings in SQL Server

Learn how to effectively combine month and year strings and convert them into a proper date format in SQL Server, resolving common errors encountered during string-to-date conversions.
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How to Concat and Create a Date from Strings in SQL Server

In the world of SQL Server, it’s not uncommon to encounter situations where date information is stored in individual columns, such as month and year, rather than a single date column. This can pose a challenge when you need to manipulate or analyze date data. One common issue developers face is converting these separate string values into a proper date format. In this post, we will explore a practical solution for combining month and year data into a valid date format using SQL Server.

The Problem

Imagine you have a table that stores the accounting period (month) and the accounting year in separate columns like this:

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

You need to combine these two columns, creating a date format (e.g., 01/01/2023) that can be recognized and utilized by SQL Server for date operations. However, when trying to convert these concatenated string values to a date using functions like CAST or CONVERT, you might encounter an error: "Conversion failed when converting date and/or time from character string."

The Solution

To effectively handle this, we can utilize the DATEFROMPARTS function in SQL Server. The DATEFROMPARTS function allows you to construct a date from individual year, month, and day components. Here’s a breakdown of how to implement this solution.

Step-by-Step Breakdown

Understanding the Function:

DATEFROMPARTS(year, month, day) takes three integers and returns a date. In our case, we will pass the AccountingYear, AccountingPeriod, and use 1 for the day argument since it’s a placeholder.

Constructing the SQL Query:

We will write a query that selects from your table and applies the DATEFROMPARTS function to construct the date.

Here is the SQL code to achieve this:

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

Expected Output

When this query is executed, you should see results like:

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

Conclusion

Combining month and year into a date can initially seem challenging due to type mismatch errors, but utilizing the DATEFROMPARTS function provides a straightforward solution. By passing the year, month, and a default day (1) into the function, SQL Server successfully constructs the required date format without any conversion errors.

Additional Tips

Always ensure your month and year are in the correct format (integer) before calling DATEFROMPARTS.

You can modify the day to reflect specific needs, but using '01' is commonly acceptable for financial or accounting data.

By following these steps, you will be able to overcome conversion issues and handle date strings effectively in SQL Server with ease.