How to Convert String Dates to DATETIME in SQL Server

Summary: Learn how to convert a string date to a DATETIME format in SQL Server using various functions to ensure accurate and effective data management.
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Converting a string date, such as '10/15/2008 10:06:32 PM', to a DATETIME format is a common requirement when working with SQL Server. Proper conversion is essential for performing accurate date calculations and comparisons, especially in reports and data analysis tasks.

Understanding Date Formats

When dealing with dates in SQL Server, it is critical to understand the input string format and how SQL Server interprets this format during conversion. Misinterpretation can lead to incorrect dates and produce misleading results.

Using the CONVERT Function

The CONVERT function is a versatile tool in SQL Server that can convert between different data types. To convert a string to a DATETIME, use the following syntax:

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Here, the third argument 101 specifies the MM/DD/YYYY format, which matches the input string format.

When to Use CAST vs. CONVERT

While CAST offers a simpler syntax, it doesn't provide format style options like CONVERT. Therefore, when precision is required in string-to-date conversion, especially where custom formats are involved, using CONVERT is recommended.

Handling Different Date Formats

Different regions adopt different date conventions, so the style code in the CONVERT function allows you to handle these variations. For example:

103 - DD/MM/YYYY

110 - MM-DD-YYYY

By specifying the appropriate style code, you ensure SQL Server interprets dates correctly.

Dealing with SQL Server 2005

Users working with SQL Server 2005 need to be aware of differences in function support as compared to later versions. When upgrading from SQL Server 2005, confirm all existing date conversions remain intact with any bug fixes required during the migration.

Summary

Accurate conversion of string dates to DATETIME in SQL Server is crucial for ensuring reliable data manipulation and analysis. By leveraging the CONVERT function and understanding the regional format styles, users maintain data integrity and enhance the reliability of SQL queries.

Whether you're working with SQL Server 2005 or newer versions, mastering date conversion techniques builds a strong foundation for effective database management practices.