The PARSE function in SQL Server and some other databases is used to convert a string representation of a date and time into a datetime data type. It allows you to specify the culture (locale) to be used during the conversion, which can be very helpful when dealing with different date formats.
Syntax
PARSE (string_value AS data_type [ USING culture ] )
- string_value: The string representation of the date/time that you want to convert.
- data_type: The target data type (usually DATETIME, DATE, DATETIME2, etc.).
- culture: Optional. A string that defines the culture for the conversion (e.g., 'en-US' for United States, 'fr-FR' for French, etc.).
Examples
1. Basic Conversion:
You have a simple string date, like '2023-10-01', and you want to convert it to a DATETIME.
DECLARE @dateString NVARCHAR(50) = '2023-10-01';
SELECT PARSE(@dateString AS DATETIME) AS ParsedDate;
2. Using a Specific Culture:
If you have a date string formatted according to a specific culture, you can specify that culture in the PARSE function. For example:
DECLARE @dateString NVARCHAR(50) = '10/01/2023'; -- MM/DD/YYYY format
SELECT PARSE(@dateString AS DATETIME USING 'en-US') AS ParsedDate;
If the date string is in a different format, such as DD/MM/YYYY and the culture is set to French:
DECLARE @dateString NVARCHAR(50) = '01/10/2023'; -- DD/MM/YYYY format
SELECT PARSE(@dateString AS DATETIME USING 'fr-FR') AS ParsedDate;
3. Handling Invalid Formats:
If the string cannot be converted to a datetime value due to an invalid format, the query will result in an error. It's a good practice to ensure the data you are trying to convert is in the expected format.
Important Notes:
- The PARSE function is more flexible than CAST or CONVERT, especially in handling various date formats, but it might be slower due to the need to account for cultures.
- Always check the compatibility of your SQL Server version with the PARSE function, as it was introduced in SQL Server 2012.
- If performance is critical, consider using TRY_PARSE which returns NULL rather than an error when conversion fails.
Example of TRY_PARSE:
If you want to safely handle possible conversion errors:
DECLARE @dateString NVARCHAR(50) = 'invalid date';
SELECT TRY_PARSE(@dateString AS DATETIME USING 'en-US') AS ParsedDate;
-- This will return NULL instead of raising an error.
This way, PARSE can be a very effective tool for converting date and time string representations into actual date/time types in your SQL queries.