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SQLite Database Management System
Overview
Sqlite management is difficult. Mainly because of the features SQLite has not
implemented.
Because of the limited functionality of SQLite, it is only useful for small systems
that do not require the full power of standard relational databases. Also the slow response from SQLite does not
make it useful for larger files.
ALTER TABLE support
Only the RENAME TABLE and ADD COLUMN variants of the ALTER TABLE command are supported.
Other kinds of ALTER TABLE operations such as DROP COLUMN, ALTER COLUMN, ADD CONSTRAINT, and so forth are omitted.
Because you cannot drop a field, or add before or after fields, the system has
to create temporary tables exactly like the table you alter, and then create a new database with the features you
requested. This means keeping the integrity of the data. Dropping a field causes index problems, and some indexes
that may have been unique are no longer unique and it causes errors. The system tries to maintain your unique indices.
However if it cannot, it becomes a standard index.
Primary index.
This system does not support the Primary Index concept. Primary indices are also a big problem with SQLite. The
only reason for the Primary index is that the first release of SQLite only supported a single primary index. It
is no longer necessary. Creating a unique index on the field accomplishes the same thing.
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