On 04/23/2013 12:29 AM, John R Pierce wrote:
On 4/22/2013 3:13 PM, Thomas Kellerer wrote:
Abhinav Dwivedi wrote on 22.04.2013 07:12:
select * from district where statecode in (Select districtcode from
state)
Please note that the attribute districtcode is not existent in the
table state and
if this query i.e. Select districtcode from state is executed in
isolation then it
correctly throws an error message. But when this incorrect query is
made inner query
of a nested query then the whole query wrongly returns a dataset.
I assume the column districtcode is present in the table district. In
that case this is not a bug,
this is required by the SQL standard. The sub-query references the
column from the outer query.
And I don't think this has been changed with 9.x (nor will it ever).
if that had been written as an explicit join, there would be less
ambiguity.
select district.* from district join state using(statecode);
assuming that's even what you wanted.
That's not an equivalent query. Abhinav is doing a semi-join.
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