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Answer: Generated columns are created by defining a rule or expression that generates the column's values based on other columns. For example, you can add a generated column 'name_length' to a table 'employees' that calculates the length of the 'name' column.
Generated columns are created by defining a rule or expression that generates the column's values based on other columns. For example, you can add a generated column 'name_length' to a table 'employees' using the following SQL command: 'ALTER TABLE employees ADD COLUMN name_length INT GENERATED ALWAYS AS (LENGTH(name)) VIRTUAL;'
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Describe the process of creating a generated column in a Delta Lake table. Provide an example of how you would add a generated column to an existing table to store the length of a text column.
A
Generated columns can be added by directly inserting values into the new column without any predefined rules.
B
Generated columns are created by defining a rule or expression that generates the column's values based on other columns. For example, you can add a generated column 'name_length' to a table 'employees' that calculates the length of the 'name' column.
C
Generated columns are automatically created by the system based on the data type of existing columns.
D
Generated columns cannot be added to existing tables and must be defined at the time of table creation.
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