What is the usage of the SQL cast function?

The SQL CAST function is used to convert a value from one data type to another. It can be used in SELECT statements to convert the data type of a column to a different data type, as well as in INSERT, UPDATE, and DELETE statements to convert the data type of constants or expressions to a different data type.

The general syntax of the CAST function is as follows:
CAST(expression AS data_type)

In this case, the expression represents the value to be converted, and the data_type is the type of data it should be converted into.

For example, converting the values of a string column to an integer type:

SELECT CAST(column_name AS INT)
FROM table_name

Alternatively, convert the values in a date column to string type:
SELECT CAST(date_column AS VARCHAR)
FROM table_name

Common data type conversions include converting strings to integers, converting integers to strings, and converting dates to strings. When performing data type conversions, it is important to consider the compatibility between the source data type and the target data type, as well as the potential issues of data loss or format changes that may arise.