Hi James,

your query has to look like

select <something> from <relation>

Your example queries look like

select <something>

Taking your first example, you may write

SELECT
case RDB$RELATION_NAME
when 'SCHEMA_VERSION' then 1
else 0
end
FROM RDB$RELATIONS

to achieve the second.

I'd write

SELECT
ii(RDB$RELATION_NAME = 'SCHEMA_VERSION', 1, 0)
FROM RDB$RELATIONS

but this is identical in respect of performance.



Am 04.04.2014 15:30, schrieb James Schumacher:

>
>
> Hello,
>
> I am new to Firebird, I have experience using MS SQL. I am trying to
> convert some code that performs various checks but having problems with
> the syntax. One thing I need to convert is SQL to detect whether a
> table exists.
>
> I have tried these in Squirrel and isql connected to an embedded db
> version Firebird 2.5
>
> I tried the following
>
> SELECT RDB$RELATION_NAME FROM RDB$RELATIONS
> WHERE RDB$RELATION_NAME = 'SCHEMA_VERSION'
>
> works fine. I went on to:
>
> select case when exists(SELECT RDB$RELATION_NAME FROM RDB$RELATIONS
> WHERE RDB$RELATION_NAME = 'SCHEMA_VERSION') then 1 else 0 end;
>
> Error: GDS Exception. 335544569. Dynamic SQL Error
> SQL error code = -104
> Unexpected end of command - line 2, column 62
> SQLState: 42000
> ErrorCode: 335544569
>
> I thought maybe firebird wants named result so I tried
>
> select (case when exists(SELECT RDB$RELATION_NAME FROM RDB$RELATIONS
> WHERE RDB$RELATION_NAME = 'SCHEMA_VERSION') then 1 else 0 end) as
> result;
>
> Error: GDS Exception. 335544569. Dynamic SQL Error
> SQL error code = -104
> Unexpected end of command - line 2, column 70
> SQLState: 42000
> ErrorCode: 335544569
>
> I am now down to some very basic queries that work in MS SQL but not in
> firebird:
>
> SELECT CASE
> WHEN 4 = 5 THEN 1
> WHEN 5 = 6 THEN 2
> ELSE 0
> END;
>
> Error: GDS Exception. 335544569. Dynamic SQL Error
> SQL error code = -104
> Unexpected end of command - line 5, column 2
> SQLState: 42000
> ErrorCode: 335544569
>
> or
>
> SELECT (CASE
> WHEN 4 = 5 THEN 1
> WHEN 5 = 6 THEN 2
> ELSE 0
> END) as result;
>
> Error: GDS Exception. 335544569. Dynamic SQL Error
> SQL error code = -104
> Unexpected end of command - line 5, column 10
> SQLState: 42000
> ErrorCode: 335544569
>
> I have looked at the following documentation but I don't see what I am
> doing wrong
>
> http://www.firebirdsql.org/file/documentation/reference_manuals/reference_material/html/langrefupd25.html
>
>
> thank you for any help you can give,
>
> Jim s
>
>

--
Mit freundlichen Grüßen,

Thomas Beckmann
Diplom-Informatiker


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