How to create virtual columns in teradata?

@lottie 

In Teradata, you can create virtual columns using computed columns. Computed columns are columns that are calculated based on an expression or a combination of other columns in a table.

Here's an example of how to create a virtual column in Teradata:

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CREATE TABLE my_table (
    id INTEGER,
    first_name VARCHAR(50),
    last_name VARCHAR(50),
    full_name VARCHAR(100) GENERATED ALWAYS AS (first_name || ' ' || last_name) 
);

In this example, the full_name column is a virtual column that concatenates the first_name and last_name columns to create a full name. The GENERATED ALWAYS AS clause is used to define the expression used to calculate the value of the virtual column.

You can use any valid SQL expression in the GENERATED ALWAYS AS clause to calculate the value of the virtual column. The virtual column will be calculated on the fly whenever it is queried, and will not be physically stored in the table.

Keep in mind that computed columns may impact query performance, so it's important to consider the performance implications when creating virtual columns in Teradata.