You should cast before you divide, but also you were missing a subquery to get the total count from the table. Here’s the sample. select random_int, count(random_int) as Count, cast(count(random_int) as decimal(7,2)) / cast((select count(random_int) from test) as decimal(7,2)) as Percent from test group by random_int order by random_int;
There’s a clear best option out of the three you suggested (plus one from the comments). BIGINT — uses just 8 bytes, but the largest BIGINT only has 19 decimal digits; if you divide by 1018, the largest value you can represent is 9.22, which isn’t enough range. DOUBLE — only has 15–17 decimal digits … Read more
There are many possible causes for serialization failures. Technically, a deadlock between two transactions is one form of serialization failure, and can potentially happen at any isolation level if there are concurrent modifications to the schema (database structure). Since you’re asking about PostgreSQL, you should be aware that in PostgreSQL this type of serialization failure … Read more
Update 2024-01-17: SQL Fiddle no longer works for Oracle and seems to have lost many old fiddles. See the other answer for a more up-to-date list. SQL Fiddle Here is a trivial example of use: http://sqlfiddle.com/#!4/8cf15/5
The parameter you give to the sqlite3 program is the database file name. To execute commands from a file, you must redirect the input to that file: $ sqlite3 mydatabase.db < SQLTableTransfer or tell it to read from that file: $ sqlite3 mydatabase.db “.read SQLTableTransfer”
declare @D as datetime=”2012-01-02T12:04:11.443″ select dateadd(hour, datediff(hour, 0, @D), 0) select dateadd(minute, datediff(minute, 0, @D), 0)
Yes it is strange and counterintuitive. Hugh Darwen theorises about how this state of affairs came about: Do you take SELECT-FROM-WHERE for granted, or do you, like me, find it rather curious that the System R team should have spurned the normal way of writing expressions of arbitrary complexity in favour of something utterly idiosyncratic … Read more
Here are two ways I know of to update an entity in the database without doing a retrieval of the entity first: //Assuming person is detached from the context //for both examples public class Person { public int Id { get; set; } public string Name { get; set; } public DateTime BornOn { get; … Read more
using (var conn = new SqlConnection(SomeConnectionString)) using (var cmd = conn.CreateCommand()) { conn.Open(); cmd.CommandText = “SELECT * FROM learer WHERE id = @id”; cmd.Parameters.AddWithValue(“@id”, index); using (var reader = cmd.ExecuteReader()) { if (reader.Read()) { learerLabel.Text = reader.GetString(reader.GetOrdinal(“somecolumn”)) } } }