What does the SQL keyword CAST do?

The SQL keyword CAST is used to convert a data type of a column into a new data type. Here are the steps to use it:

1. Identify the column and its current data type that you want to convert. This could be any column in your database that holds data in a specific data type.

2. Decide the new data type you want to convert the column to. This could be any valid SQL data type like INT, VARCHAR, DATE, etc.

3. Use the CAST function in your SQL query. The syntax for using CAST is as follows:

   CAST (expression AS data_type)

   Here, 'expression' is the column you want to convert and 'data_type' is the new data type you want to convert the column to.

4. Run the SQL query. The CAST function will convert the data type of the column for the duration of the query. It does not permanently change the data type of the column in the database.

For example, if you have a column 'age' in your database that is stored as VARCHAR and you want to convert it to INT, you would use the CAST function as follows:

SELECT CAST(age AS INT) FROM table_name;

This will return the 'age' column as an integer data type.