Hi,

This has nothing to do with FDB. Parameters (?) are implemented by
Firebird engine itself, FDB just supports it. So you should ask such
question in Firebird-support list, or check out
https://stackoverflow.com/questions/37348807/data-type-unknown-in-case-expression-with-only-parameters-as-values

regards
Pavel Cisar
IBPhoenix

Dne 15.4.2018 v 03:03 maxirobaina@... [firebird-python] napsal(a):

> Hi,
>
> I have the next sql command
>
> sql = 'SELECT
> "EXPRESSIONS_COMPANY"."ID",
> "EXPRESSIONS_COMPANY"."NAME",
> "EXPRESSIONS_COMPANY"."NUM_EMPLOYEES",
> "EXPRESSIONS_COMPANY"."NUM_CHAIRS",
> "EXPRESSIONS_COMPANY"."CEO_ID",
> "EXPRESSIONS_COMPANY"."POINT_OF_CONTACT_ID",
> ? AS "FOO"
> FROM "EXPRESSIONS_COMPANY"
> WHERE ? = ?
> ORDER BY "EXPRESSIONS_COMPANY"."NAME" ASC'
>
> Running this sql
> cur.execute(sql, ['value', 'value', 'value'])
>
> Raise an exception:
> SQL error code = -804 - Data type unknown'
>
> Of course, fdb doesn't replace params from entire sql command, just from where clause.
>
> Is this behavior the standard according to python db-api ?
> Is there another approach to accomplish using fdb without make a string replacement ?
>
>
> Regards
> Maxi
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