need help with slow executing code

Question

3.33/5 (3 votes)

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How can I write this code more efficiently so it will execute faster?

C#

DataTable dt1 = new DataTable();
dt1.Load(DbInfo.DataRdr(Conn, "SELECT DISTINCT     Events.Location FROM Events WHERE Events.Location NOT IN (SELECT Code FROM Locations)"));
  int cnt = 0;
  for (int i = 0; i < dt1.Rows.Count; i++)
  {
    Logging.Write(SetLength(" ", 10) + dt1.Rows[i]["Location"].ToString());
  }

---------------------
DbInfo.DataRdr returns a SqlDataReader object.

Posted 13-Apr-11 10:07am

Mastersev

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Comments

wizardzz 13-Apr-11 17:03pm

What's taking long, the query or the loop?

3 solutions

Solution 1

If you write 5,000,000 records, yes it will be very slow. Read this, I hope it helps you.

left-outer-join-vs-not-exists1/[^]

left-outer-join-vs-not-exists2/[^]

Posted 13-Apr-11 11:04am

luisnike19

Solution 3

In my openion above code is good.

Posted 13-Apr-11 19:38pm

Prasanta_Prince

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Costica U · Accepted Answer · 2011-04-13T16:05:00

Solution 2

This should run a little faster

C#

SqlDataReader reader = DbInfo.DataRdr(Conn, "SELECT DISTINCT Events.Location FROM Events WHERE 
NOT EXISTS( SELECT 1 FROM Location WHERE Code = Events.Location")
int colOrdinal = reader.GetOrdinal("Location");
while(reader.Read())
   {
   Logging.Write(SetLength(" ", 10) + reader.GetString(colOrdinal));
   }

Posted 13-Apr-11 16:05pm

Costica U

Comments

Mastersev 13-Apr-11 23:01pm

thank you very much sir

Costica U 14-Apr-11 11:06am

You are welcome