Final answer:
In SQL, if a name for a calculated column in a query is not provided, the database usually auto-generates a default name, which might be a derivative of the calculation expression or a generic name like 'Expr1'.
Step-by-step explanation:
When a calculated column is added to a query result set in SQL and a name is not explicitly provided for it using an alias, most SQL databases automatically generate a default name for the column.
Typically, this default name is derived from the calculation expression itself, but it can sometimes appear as Expr1, Expr2, and so on, depending on the database management system.
It is always recommended to explicitly name calculated columns using the AS clause for better readability and maintenance of SQL queries.
When the column name of a calculated column is not provided in the query definition, the column name in the query results is typically assigned a default or system-generated name.
The specific naming conventions may vary depending on the database system being used.
In many database systems, the default naming convention for a calculated column involves combining the function or expression used to calculate the column with an internal identifier.
For example, it might look like "Expr1," "Column1," or something similar. The exact naming convention can depend on the database system and the specific query tool being used.
It's always a good practice to provide a meaningful alias for calculated columns in the query definition to make the results more understandable and user-friendly. For example: