How is intersection represented in SQL?

The representation of intersection in SQL is done using the comma, specifically in the context of the JOIN operation. In SQL, when you want to retrieve records that match in two sets, you usually perform a JOIN between tables or subqueries. The comma is utilized to indicate that both conditions must be satisfied in the selection of records, effectively capturing the intersection of the datasets involved.

Using a comma within a WHERE clause after a JOIN or in the SELECT statement allows SQL to filter results that meet all specified criteria, which is how intersections are logically constructed in terms of returning rows that exist in both tables or datasets. This is particularly evident in inner joins, where records are returned only when there is a match in both tables.

Other symbols, such as the space, semicolon, or asterisk, do not represent the concept of intersection in SQL properly. A space does not denote any specific SQL operation, a semicolon is used to terminate SQL statements, and an asterisk is typically used in SQL to select all columns. Therefore, while they have specific roles in SQL syntax, they do not relate to representing intersection in the way that a comma does.