On Sunday, 12 January, 2020 15:29, Richard Damon <rich...@damon-family.org> wrote:
>On 1/12/20 5:25 PM, Tom Browder wrote: >> On Sun, Jan 12, 2020 at 14:05 Keith Medcalf <kmedc...@dessus.com> wrote: >>> On Sunday, 12 January, 2020 09:03, Tom Browder <tom.brow...@gmail.com> >>> wrote: >>>> Am I missing something? I thought every column has to have a type? >>> Close, but no banana. Every value has a type. A column may contain >>> multiple values (as in one per row).... >> I assume that is just for SQLite, or am I wrong again? > That the entries for a given column in different rows can have different > types is a peculiarity of SQLite. In a 'Standard' SQL database, a column > has a defined type, and all rows will have values of that type (or NULL). It is a peculiarity of the underlying datastore used by SQLite. Many (most in fact) datastores require that all instances of the same "column" in an "entity" be the same type -- some do not (SQLite is one of them). SQL is simply a Structured Query Language that can be overlaid on a variety of datastore models, one of which is the Relational model. When SQL is used on other database organizations it is entirely possible for the "type" of a particular returned "column" to vary by row as it may have been fetched from different entities. DB-Vista, MDBS, and NOMAD are a couple of CODASYL style databases which have (optional extra) SQL query interfaces that can return data of multiple value types row by each for the same column. -- The fact that there's a Highway to Hell but only a Stairway to Heaven says a lot about anticipated traffic volume. _______________________________________________ sqlite-users mailing list sqlite-users@mailinglists.sqlite.org http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users
