Adventures in Machine Learning

Streamlining Data Conversion with SQL Server’s TRY_CONVERT() Function

Data conversion is a critical aspect of database management, especially when dealing with data sourced from various systems like CSV, Excel, and XML. SQL Server provides various conversion functions, including CONVERT() and TRY_CONVERT().

These functions can convert data from one data type to another so that database tables can provide the necessary information to the end-users or applications. In this article, we will explore the TRY_CONVERT() function and how it differs from the CONVERT() function.

SQL Server TRY_CONVERT() Function Overview

The TRY_CONVERT() function is a conversion function introduced in SQL Server 2012 onwards. It was designed to simplify data type conversions and achieve better error handling in conversion operations.

In its simplest form, the function converts an input expression of a particular data type to another specified data type. The TRY_CONVERT() function returns NULL if the conversion fails.

Here is the syntax of the TRY_CONVERT() function:

TRY_CONVERT(data_type, expression[, style])

The primary keywords in the TRY_CONVERT() function are data_type, expression, and style. The data_type specifies the target data type to which the input expression should be converted.

The expression is the input value to be converted. The optional style argument specifies the specific format of the input expression to facilitate conversions.

One of the most significant benefits of using the TRY_CONVERT() function is that it avoids the possibility of a runtime error, which may result from conversion failure. Instead of resulting in an error, it returns a NULL value.

This ensures that the data type conversion does not cause the database server to stop working, and other parts of the application can still function optimally.

Explanation of TRY_CONVERT() Function

The TRY_CONVERT() function performs a type conversion operation on an input expression, which could be a character, number, or date/time value. It allows you to specify the destination data type, and if the conversion is successful, returns the input expression in the desired data type.

Otherwise, it returns a NULL value. The TRY_CONVERT() function supports various data types, including integer, float, decimal, character, date, time, and a few others.

Additionally, you can use the optional style parameter to specify a particular format for the input expression. For instance, converting a date to a specific format or a string to a date value requires the style parameter to be set.

One important aspect of using TRY_CONVERT() is its error handling ability. When converting values to a different data type, you may encounter errors, such as overflow, data truncation, or conversion failure.

With the TRY_CONVERT() function, you can handle these errors gracefully by returning a NULL value. Doing so makes error handling less complicated, and your application can continue to run without crashing.

TRY_CONVERT() vs. CONVERT()

Now that we know what the TRY_CONVERT() function is, let’s compare it to its older brother, the CONVERT() function.

The CONVERT() function has been available in SQL Server since version 6.5 and is widely used by developers and database administrators. The CONVERT() function allows you to convert a value from one data type to another.

Like the TRY_CONVERT() function, it also has an optional style argument. The primary difference between the two functions is the way they handle errors.

The CONVERT() function, when unable to convert a data type, returns an error, making the application crash or stop. On the other hand, the TRY_CONVERT() function returns a NULL value, allowing continued processing of the application without interruption.

Another significant difference between TRY_CONVERT() and CONVERT() is that TRY_CONVERT() can handle NULL values. When converting a NULL value, the CONVERT() function returns an error.

In contrast, TRY_CONVERT() returns a NULL value, enabling the developer or database administrator to decide how to handle the NULL value more prudently.

Conclusion

In conclusion, the difference between the TRY_CONVERT() and CONVERT() functions is fundamental in application development and database administration. TRY_CONVERT() offers better error handling and more graceful NULL value handling while CONVERT() can crash an application during conversion.

Further, TRY_CONVERT() reduces the amount of error-prone code you need to write to handle errors gracefully, and hence programmers can create applications faster and with less code. To leverage the benefits and flexibility of TRY_CONVERT(), database administrators and developers should strive to adopt this function in their database management practices.

SQL Server TRY_CONVERT() Function Examples

The TRY_CONVERT() function is an excellent tool for developers who need to convert different data types in SQL Server. Understanding how to use TRY_CONVERT() ensures that developers can consistently and accurately convert data types and handle any errors that might arise in the process.

In this article, we will go through some examples of how TRY_CONVERT() can be used in different scenarios.

TRY_CONVERT() Returns NULL Example

When TRY_CONVERT() cannot perform a conversion, it returns a NULL value instead of an error. The following example demonstrates how TRY_CONVERT() returns NULL when the cast fails.

SELECT TRY_CONVERT(int, ‘NotANumber’);

Here, the input string is “NotANumber”, and the target data type is ‘int’. Because “NotANumber” cannot be converted to an integer value, the TRY_CONVERT() function returns NULL instead of raising an error.

TRY_CONVERT() Raises an Error Example

Suppose you are attempting to use the TRY_CONVERT() function to convert an XML data type to an integer data type. In this case, TRY_CONVERT() will raise an error because the conversion is not possible.

Here’s an example of how this works:

SELECT TRY_CONVERT(INT, ‘‘);

In this example, the input is an XML string, but the target data type is int, which is not compatible. As a result, the TRY_CONVERT() function throws an error.

Convert String to Decimal Examples

Converting strings to decimal values is a common task in data management. The following examples show how to use the TRY_CONVERT() function to convert a string to a decimal data type.

1. Converting an integer string to a decimal:

SELECT TRY_CONVERT(decimal(10,2), ‘123’);

Here, the input string is “123,” and the target data type is decimal(10, 2).

Because the input value can be converted successfully, the TRY_CONVERT() function returns the value 123.00. 2.

Converting a hexadecimal string to a decimal:

SELECT TRY_CONVERT(decimal(10,2), ‘0x20’);

Here, the input string is “0x20”, which is a hexadecimal notation for 32, and the target data type is decimal(10, 2). Because the input value can be converted successfully, the TRY_CONVERT() function returns the value 32.00.

Convert String to Integer Examples

Converting strings to integer values is another common task in data management. The following examples show how to use the TRY_CONVERT() function to convert a string to an integer data type.

1. Converting a string to an integer value:

SELECT TRY_CONVERT(int, ‘123’);

Here, the input string is “123,” and the target data type is int.

Because the input value can be converted successfully, the TRY_CONVERT() function returns the integer value 123. 2.

Converting a hexidecimal string to an integer value:

SELECT TRY_CONVERT(int, ‘0xFF’);

Here, the input string is “0xFF,” which is a hexadecimal notation for the integer value 255, and the target data type is int. Because the input value can be converted successfully, the TRY_CONVERT() function returns the integer value 255.

Convert Datetime to Date or Time Example

Another common operation in data management is converting datetime values to date or time values. Here are some examples of how to use the TRY_CONVERT() function to achieve these conversions.

1. Converting datetime to date:

SELECT TRY_CONVERT(date, ‘2021-10-20 14:21:35.123’);

Here, the input value is a datetime value, and the target data type is date.

The TRY_CONVERT() function extracts the date component from the input value and returns it as a date value of “2021-10-20.”

2. Converting datetime to time:

SELECT TRY_CONVERT(time, ‘2021-10-20 14:21:35.123’);

Here, the input value is a datetime value, and the target data type is time.

The TRY_CONVERT() function extracts the time component from the input value and returns it as a time value of “14:21:35.1230000.”

Conclusion

In summary, TRY_CONVERT() is a useful function in SQL Server that enables developers to safely and accurately convert data types. It provides better error handling and eliminates the possibility of program crashes from incompatible data types.

In this article, we have seen some examples of how to use TRY_CONVERT() for different types of data conversion. By mastering the TRY_CONVERT() function, developers can unlock the full potential of SQL Server for data management.

In conclusion, the TRY_CONVERT() function in SQL Server is a critical tool for developers who need to convert different data types in a database. It allows for smooth conversions with better error handling and eliminates the possibility of program crashes from incompatible data types.

We have demonstrated how TRY_CONVERT() can be used in various scenarios using examples showcased in this article, covering conversions from datetimes to dates, strings to integers/decimals, and more. By mastering the TRY_CONVERT() function, developers can unlock the full potential of SQL Server for streamlined data management.

Remember to use TRY_CONVERT() when you need to convert data types, and enjoy the benefits of quick and reliable conversions.