What is CAST function in SQL?

What is CAST function in SQL?

In SQL, the CAST function is used to convert a value from one data type to another. This function is often used to convert values to a specific data type so that they can be used in a specific context, such as in a mathematical operation or in a comparison.

Here is an example of how to use the CAST function in SQL:

SELECT CAST('123' AS INT)

In this example, the CAST function is used to convert the string value '123' to an integer data type. The INT keyword specifies the target data type, which in this case is the integer data type. The CAST function returns the value 123 as an integer.

How to CAST to 2 decimal places in SQL

To convert a value to a decimal data type with two decimal places in SQL, you can use the CAST function and the DECIMAL data type, along with the ROUND function.

Here is an example of how to do this:

SELECT CAST(ROUND(1.23456, 2) AS DECIMAL(10, 2))

In this example, the ROUND function is used to round the value 1.23456 to two decimal places, resulting in the value 1.23. This value is then passed to the CAST function, which converts it to the DECIMAL data type with a precision of 10 and a scale of 2. The CAST function returns the value 1.23 as a decimal data type with two decimal places.

Alternatively, you can use the FORMAT function to format the value as a string with two decimal places, like this:

SELECT FORMAT(1.23456, 'N2')

In this example, the FORMAT function is used to format the value 1.23456 as a string with two decimal places. The N2 format string specifies that the value should be formatted as a number with two decimal places. The FORMAT function returns the value 1.23 as a string.

Both of these methods can be used to convert a value to a decimal data type with two decimal places in SQL. The method you choose will depend on whether you want the value to be returned as a decimal data type or as a string.

CAST vs. CONVERT

In SQL, the CAST and CONVERT functions are both used to convert a value from one data type to another.

Both functions can be used to perform the same types of conversions, and in most cases they can be used interchangeably.

The main difference between the two functions is that CAST is an ANSI standard function, while CONVERT is a proprietary function specific to Microsoft SQL Server.

Conclusion

The CAST function is useful because it allows you to convert values to a specific data type in a way that is independent of the original data type.

This can be useful when you are working with data from multiple sources that may have different data types, or when you want to ensure that values are converted to the correct data type before being used in a specific context.