>>>>> Glynn Clements <[EMAIL PROTECTED]> writes:
[...]
>>> IOW, change db/drivers/sqlite/describe.c to parse the sqlite_master
>>> table according to the syntax used by
>>> db/drivers/sqlite/create_table.c.
>> Hm. Now I see sqlite3_column_decltype () in the SQLite API
>> reference?
> Er, right. ISTR that there are reasons why the SQLite driver doesn't
> rely upon that much. However, I suspect that it will produce the same
> result as parsing the string from sqlite_master.
Most probably.
> IIRC, the main problem is that sqlite3_column_decltype() only works
> for actual columns, not expressions, subselects etc, but the code
> in question has to be able to describe the format of rows returned
> by arbitrary SELECT statements, not just tables.
> So it falls back to sqlite3_column_type(), which returns the type
> of the column's data. but that only works if you have a valid
> row. If a select doesn't return any rows, you lose. Also,
> sqlite3_column_type() only understands null, integer, float, text
> and blob types.
I wonder, how it's done for other RDBMS? E. g., would there be
a table, like:
CREATE TABLE foo (foo NUMERIC, bar TEXT);
What would be the type of the only column of the query like:
SELECT foo || bar FROM foo;
Or, the same question for the table like:
CREATE TABLE foo (foo VARCHAR (5), bar CHAR (5));
It seems that the only sane type to be inferred from the
expression is TEXT (for either case.)
And I guess, sqlite3_column_type () will return either text or
blob.
> Apart from needing to fall-back to the data type for expressions,
> another problem is that it coerces the decltype to one of SQLite's
> limited set of types, then converts that to one of the DB_SQL_*
> types, losing information in the process.
That doesn't feel sound.
> However, I don't know if it does this for a specific reason. I
> suspect the only way to find out is to try it and see what breaks.
[...]
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