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Is "top 1" in sql skipping the where clause
Select top 1 afield from atable where secondfield = 3 I am telling you there is not record with secondfield = 3 If I run this the sql server it returns no record That was what I expected If I run this in the c# enviroment it returns the top most record regardless whether the where clause is true or not. Does "top" have precedence over the where clause ?
3 ответов
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@Sneeze, as I see it "TOP" only limits the number of records returned, it shouldn't interfere the "WHERE" clause.
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Oeps I found my mistake. It was in the sql-statement
"Select top 1 afield from atable where secondfield = secondfield"
Not using the variable secondfield but just have plain text there.
Still I do not understand why it did return a record.
But when I use the variable it does not return any result anymore as it should.
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@IPang thank you for answering.
I starting to think it has something to do with the way I query the database. Becaus if I ran the same command in the sql server it gave me the correct results.
This is the code I use to query the database.
try
{
cnn.Open();
cmd = new SqlCommand(sql, cnn);
reader = cmd.ExecuteReader();
while (reader.Read())
{
MessageBox.Show(reader.GetValue(0) );
}
reader.Close();
cmd.Dispose();
cnn.Close(); }
catch (Exception ex)
{
MessageBox.Show("Can not open connection ! ");
}