

SQLite cannot drop columns - Jarred
http://www.sqlite.org/faq.html#q11

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MarkR42
Other databases can't drop columns either. In most cases (row-based databases
such as the default storage on pgsql, microsoft, oracle, mysql etc), dropping
a column, if that syntax is available, internally rebuilds the table with the
column omitted.

The data are stored in row-major order (they are in sqlite too) and to drop a
column, you need to effectively rewrite every existing row (at least, all the
ones where that column is non-null)

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MarkR42
Essentially, ALTER TABLE ... DROP COLUMN is just syntactic sugar, you can do
the operation equally efficiently (albeit with more complexity) with other
statements.

In any case, sqlite CAN at least drop indexes, which is something that some
versions of MySQL did quite badly (without a table rebuild)

