Published on

August 25, 2011

Introduction to SQL Server Conversion Functions

In SQL Server, there are several conversion functions available that allow you to convert data from one data type to another. One of the new conversion functions introduced in SQL Server Denali is the PARSE() function. In this blog post, we will explore the PARSE() function and its usage.

The PARSE() function is used to convert a string value to either a numeric or date/time format. It relies on the Common Language Runtime (CLR) to perform the conversion. If the string value cannot be converted to the specified format, an error will be returned. It’s important to note that PARSE() only works for converting string values to numeric and date/time formats. For other data types, you can use the traditional CAST or CONVERT functions.

It’s worth mentioning that there is a slight performance overhead when using the PARSE() function to convert string values. This is because the function needs to parse the string and perform the conversion.

Let’s take a look at some examples to understand how the PARSE() function works:

Example 1: Converting String to INT

SELECT PARSE('100.000' AS INT) AS ValueInt

This query will return the result as 100.

Example 2: Converting String to Date/Time

SELECT PARSE('July 30, 2011' AS DATETIME) AS ValueDT

This query will return the result as 2011-07-30 00:00:00.000.

Example 3: Converting String to INT from Table

SELECT SP.[StateProvinceCode], PARSE(A.[PostalCode] AS INT) PostCode
FROM [Person].[Address] A
INNER JOIN [Person].[StateProvince] SP ON SP.StateProvinceID = A.StateProvinceID
WHERE SP.[CountryRegionCode] = 'US' AND LEN(A.[PostalCode]) <= 6

In this example, we are converting the PostalCode column from the nvarchar format to INT using the PARSE() function.

It’s important to note that if the string cannot be converted to INT because it contains alphabets or other non-numeric characters, the PARSE() function will throw an error.

In the next blog post, we will explore the usage of the TRY_PARSE() function, which provides a way to handle conversion errors more gracefully.

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