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SQL tables are not actually sets at all since you can insert duplicate rows! In practice they usually are though.
by TexanFeller 4y ago
SQL tables are not actually sets at all since you can insert duplicate rows! In practice they usually are though.
- packetlost 4y agoYou can't actually insert a complete duplicate row because the ROWID (or whatever your particular RDBMS calls it) is a implicit, but unique property of each row (and corresponds to the offset in the file the row is located at). Further, while tables can be the identity element of all records they contain, they themselves aren't really a set. Usually when people associate set theory with SQL, it's with queries (and their results).