Explain CAST() in MySQL

 

In MySQL, the CAST() function is used to convert a value from one data type to another. It allows you to explicitly specify the target data type for a given expression or column. This can be useful when you need to perform operations that involve different data types or when you want to ensure a specific data type for a result.

The basic syntax of the CAST() function is as follows:

sql
CAST(expression AS data_type)

Here, expression is the value or column that you want to convert, and data_type is the target data type to which you want to cast the expression.

For example, let's say you have a column named age of type VARCHAR (string) and you want to convert it to an integer so that you can perform numeric operations. You can use CAST() as follows:

sql
SELECT name, CAST(age AS SIGNED) AS age_numeric
FROM users;

In this example, the CAST(age AS SIGNED) expression converts the age column from a string to a signed integer. The result will be a new column named age_numeric containing the converted values.

It's important to note that the success of the CAST() operation depends on the compatibility of the source and target data types. If the conversion is not possible, an error may occur. Therefore, it's a good practice to ensure that the types are compatible before using CAST().