SQL Server is one of the most popular relational database management systems in the world, known for its advanced features and ease of use. Among the plethora of functions available in SQL Server, the CONVERT() function is a handy tool that can be used to convert data types, among other things.
In this article, we will explore the syntax and working of the CONVERT() function in SQL Server, while also discussing its differences with the CAST() function. We will also provide examples demonstrating its usage and working.
SQL Server CONVERT() Function Syntax:
The syntax of the CONVERT() function in SQL Server is as follows:
CONVERT(target_type[(length)], expression[, style])
Here, the target_type specifies the data type to which the expression is to be converted, with length (optional) being the length of the target type. The expression is the value to be converted, and the style (again optional) is the style of the data in which it will be displayed.
Let us look at an example to understand this better. Differences between CONVERT() and CAST() Functions:
CAST and CONVERT are two functions that are frequently used for type casting in SQL Server.
While both of these functions can convert one data type to another, they have different syntax and working. CAST provides a simpler way of type casting, whereas CONVERT is more versatile.
Some of the key differences between the two functions are:
1. CAST operates only on the original data type of the value, whereas CONVERT can take style and length arguments to convert the data type.
2. CONVERT can convert data between different formats and styles, while CAST can only change the type.
3. The performance of CAST is better than that of CONVERT.
SQL Server CONVERT() Function Examples:
Now that we understand the syntax and differences between the CONVERT() and CAST() functions, let us take a look at some examples of the CONVERT() function in SQL Server. 1.
Converting Decimal to Integer:
DECLARE @value DECIMAL(4,2) = 9.99;
SELECT CONVERT(INT, @value);
Here, we declare a decimal value and then use the CONVERT() function to convert it into an integer. The output will be 9.
2. Converting Decimal to Another Decimal with Different Length:
DECLARE @value DECIMAL(4,2) = 9.99;
SELECT CONVERT(DECIMAL(5, 1), @value);
In this example, we convert a decimal value to another decimal value with a different length.
We specify the target type as decimal(5,1), which means the resulting value will have five digits in total, with one digit after the decimal point. Hence, the output will be 9.990.
3. Converting String to a Datetime Value:
DECLARE @value VARCHAR(20) = ‘2022-05-31 20:15:00’;
SELECT CONVERT(DATETIME, @value);
Here, we convert a string value (in date time format) to a datetime value using the CONVERT() function.
The output will be ‘2022-05-31 20:15:00.000’. 4.
Converting a Datetime Value to a String Value:
DECLARE @value DATETIME = ‘2022-05-31 20:15:00’;
SELECT CONVERT(VARCHAR(25), @value, 120);
Lastly, we convert a datetime value to a string value using the CONVERT() function. We specify the style as 120, which represents YYYY-MM-DD HH:MI:SS.
The output will be ‘2022-05-31 20:15:00’. Conclusion:
In conclusion, the CONVERT() function is an essential tool in SQL Server for data type conversion, and can save time and effort in data manipulation tasks.
Its versatile syntax and ability to convert data between different formats and styles make it a must-have for relational database developers and administrators. Before using the CONVERT() function, it is essential to understand its syntax and working, and also to know the differences between the CONVERT() and CAST() functions.
Hopefully, this article has provided you with a detailed understanding of the same. In this article, we explored the syntax and working of the SQL Server CONVERT() function, highlighting its importance in data type conversion.
We also discussed the differences between CONVERT() and the CAST() functions, and provided examples demonstrating their usage. By understanding the syntax and differences between these functions, database developers and administrators can save time and effort in data manipulation tasks.
The takeaway from this article is that the CONVERT() function is an essential tool for data manipulation, and its versatile syntax and ability to convert data between different formats and styles make it a must-have for relational database management.