ill have a database with 1 table and 3 fields:
ID FIRSTNAME LASTNAME
(the ID field will be the auto incrementing index)
there might be 10 records in the DB, there might be 10,000.
i need to open the DB and randomly select a record (and then display the
name, which i dont have a problem with)
how can i randomly select a record? im guessing id have to open a recordset
and check the count to get the number of records, so lets say there were 100
records. i imagine i would have to generate a random number between 1 and
100....
anyone have a small example?
Sep 8 '06
26  3160 
this is what i have working so far... tell me what you think:
<%
Dim oConn, oRS, randNum
Set oConn=Server.Cr eateObject("ADO DB.Connection")
Set oRS=Server.Crea teObject("ADODB .recordset")
oConn.Provider= "Microsoft.Jet. OLEDB.4.0"
oConn.Open Server.MapPath( "temp.mdb")
oRS.Open "SELECT EMAIL_ADDRESS FROM TABLE1", oConn, adOpenStatic, adLockReadOnly
Randomize()
randNum = CInt((oRS.Recor dCount - 1) * Rnd)
Response.Write( "RecordCoun t: " & oRS.RecordCount & "<br><br>")
oRS.Move randNum
Response.Write oRS("EMAIL_ADDR ESS")
oRS.close
oConn.close
Set oConn = nothing
Set oRS = nothing
%>
this opens up the table, gets a count of num records, generates a random number between 0 and numrecords-1, then moves to that record, and displays a random email address.
seems like it works perfectly... do you see any issues?
"Aaron Bertrand [SQL Server MVP]" <te*****@dnartr eb.noraawrote in message news:OD******** ******@TK2MSFTN GP03.phx.gbl...
i dont have a database ready yet to TRY it. so instead im trying to
UNDERSTAND it first.
my confusion is in the fact that im thinking if i have 100 records, i need
to generate a random number between 1 and 100 so that i can open THAT
random record. do you see what im trying to do?
Sort of.
The problem is, if you have a number between 1 and 100, and you are trying
to get the row where [TableName]ID = that number, you're going to be
disappointed when you don't have a perfectly sequential set of [TableName]ID
values (even if the total number is exactly 100). Because of deletes,
rollbacks, and failures, you are likely going to have gaps in your
[TableName]ID. This is why the top solution is better than a solution that
relies on mapping recordcount to actual data.
A
Jimmy wrote:
this is what i have working so far... tell me what you think:
oRS.Open "SELECT EMAIL_ADDRESS FROM TABLE1", oConn, adOpenStatic,
adLockReadOnly
Randomize()
randNum = CInt((oRS.Recor dCount - 1) * Rnd)
Response.Write( "RecordCoun t: " & oRS.RecordCount & "<br><br>")
oRS.Move randNum
>
seems like it works perfectly... do you see any issues?
Yes. You're retrieving all the records from the database when you only
need one of them. Not a very efficient use of network or server
resources.
--
Microsoft MVP -- ASP/ASP.NET
Please reply to the newsgroup. The email account listed in my From
header is my spam trap, so I don't check it very often. You will get a
quicker response by posting to the newsgroup.
thank you.
im currently testing with an access db. do you see any issues with my
previous random record generating code?
"Bob Barrows [MVP]" <re******@NOyah oo.SPAMcomwrote in message
news:%2******** ********@TK2MSF TNGP04.phx.gbl. ..
Does either the pubs or Northwind sample database come with SQLExpress?
If so, apply the example query to a table in one of those databases.
Let's look at the query:
sql = "SELECT TOP 1
TOP 1 tells it to return only the first record in the resultset
cols," & _
cols is meant to be a list of the columns you wish the query to return
"r = Rnd(" & randNum & ")" & _
This assigns a random number to each record in the resultset (prior to
TOP being applied)
"FROM TableName " & _
"ORDER BY r"
Without the "TOP 1", you would have a resultset containing the columns
specified by "cols" as well as a calculated column (called r) containing
a random number generated by the Rnd function, ordered by the random
number assigned to each record. The "TOP 1" returns the first one. So
you don't need to know how many records are in your table.
Jimmy wrote:
>i dont have a database ready yet to TRY it. so instead im trying to
UNDERSTAND it first.
my confusion is in the fact that im thinking if i have 100 records, i
need to generate a random number between 1 and 100 so that i can open
THAT random record. do you see what im trying to do?
"Aaron Bertrand [SQL Server MVP]" <te*****@dnartr eb.noraawrote in
message news:uq******** ******@TK2MSFTN GP04.phx.gbl...
>>Did you TRY the code sample that you had questions about? The random
number is not important, it is merely used to seed the random number
in the query that gets *1* row.
I suggest you try it out.
"Jimmy" <j@j.jwrote in message
news:e4****** ********@TK2MSF TNGP05.phx.gbl. ..
if i dont know the recordhand, how will i seed the random number
generator?
obviously if i have 100 records i cant have a number generated
thats over 100
--
Microsoft MVP -- ASP/ASP.NET
Please reply to the newsgroup. The email account listed in my From
header is my spam trap, so I don't check it very often. You will get a
quicker response by posting to the newsgroup.
ok i got ya...
so is there a way to "oRS.Move" to a particular record without having to do
it this way?
ie, can i open the DB to get a record count without SELECTing anything?
"Bob Barrows [MVP]" <re******@NOyah oo.SPAMcomwrote in message
news:%2******** ********@TK2MSF TNGP05.phx.gbl. ..
Jimmy wrote:
>this is what i have working so far... tell me what you think:
oRS.Open "SELECT EMAIL_ADDRESS FROM TABLE1", oConn, adOpenStatic,
adLockReadOn ly
Randomize()
randNum = CInt((oRS.Recor dCount - 1) * Rnd)
Response.Write ("RecordCoun t: " & oRS.RecordCount & "<br><br>")
oRS.Move randNum
>>
seems like it works perfectly... do you see any issues?
Yes. You're retrieving all the records from the database when you only
need one of them. Not a very efficient use of network or server
resources.
--
Microsoft MVP -- ASP/ASP.NET
Please reply to the newsgroup. The email account listed in my From
header is my spam trap, so I don't check it very often. You will get a
quicker response by posting to the newsgroup.
Yes. Grossly inefficient. I would never do it that way. Let the database
do the job it can do so much more efficiently than any recordset/cursor
code you or I could write.
Jimmy wrote:
thank you.
im currently testing with an access db. do you see any issues with my
previous random record generating code?
"Bob Barrows [MVP]" <re******@NOyah oo.SPAMcomwrote in message
news:%2******** ********@TK2MSF TNGP04.phx.gbl. ..
>Does either the pubs or Northwind sample database come with
SQLExpress? If so, apply the example query to a table in one of
those databases.
Let's look at the query:
sql = "SELECT TOP 1
TOP 1 tells it to return only the first record in the resultset
cols," & _
cols is meant to be a list of the columns you wish the query to
return
"r = Rnd(" & randNum & ")" & _
This assigns a random number to each record in the resultset (prior
to TOP being applied)
"FROM TableName " & _
"ORDER BY r"
Without the "TOP 1", you would have a resultset containing the
columns specified by "cols" as well as a calculated column (called
r) containing a random number generated by the Rnd function, ordered
by the random number assigned to each record. The "TOP 1" returns
the first one. So you don't need to know how many records are in
your table.
Jimmy wrote:
>>i dont have a database ready yet to TRY it. so instead im trying to
UNDERSTAND it first.
my confusion is in the fact that im thinking if i have 100 records,
i need to generate a random number between 1 and 100 so that i can
open THAT random record. do you see what im trying to do?
"Aaron Bertrand [SQL Server MVP]" <te*****@dnartr eb.noraawrote in
message news:uq******** ******@TK2MSFTN GP04.phx.gbl...
Did you TRY the code sample that you had questions about? The
random number is not important, it is merely used to seed the
random number in the query that gets *1* row.
I suggest you try it out.
"Jimmy" <j@j.jwrote in message
news:e4***** *********@TK2MS FTNGP05.phx.gbl ...
if i dont know the recordhand, how will i seed the random number
generator ?
>
obviously if i have 100 records i cant have a number generated
thats over 100
--
Microsoft MVP -- ASP/ASP.NET
Please reply to the newsgroup. The email account listed in my From
header is my spam trap, so I don't check it very often. You will get
a quicker response by posting to the newsgroup.
--
Microsoft MVP -- ASP/ASP.NET
Please reply to the newsgroup. The email account listed in my From
header is my spam trap, so I don't check it very often. You will get a
quicker response by posting to the newsgroup.
>
this opens up the table, gets a count of num records, generates a random
number between 0 and numrecords-1, then moves to that record, and displays a
random email address.
seems like it works perfectly... do you see any issues?
>
I suppose you haven't read any of my comments about why the suggested route
is better. For example, you don't need to pull the whole table to the
client in order to pick a random row.
If you are going to be using SQL Server Express, then you can say it as
simply as
SELECT TOP 1 Email_Address FROM Table1 ORDER BY NEWID();
(As the link suggested way back at the start of this thread, but I still
suppose you haven't read it (at least not in full).)
A
What, this?
>randNum = (CInt((recordco unt-1) * Rnd) + 1)
Again, you need to show us what you are doing with randNum before we can
comment.
But yes, as we've already suggested, there are issues.
My guess is you are going to say
sql = "SELECT EmailAddress FROM Table1 WHERE PK = " & RandNum
And like I already commented, this won't work reliably. Never mind the
unnecessary roundtrip to count the number of rows in the table.
I think you need to stop theorizing code and deal with this when you can
actually test it against a real database and understand the differences and
what we are talking about. Until then it seems you are hellbent on just
doing it your way and ignoring our advice.
A
"Jimmy" <j@j.jwrote in message
news:Od******** ********@TK2MSF TNGP06.phx.gbl. ..
thank you.
im currently testing with an access db. do you see any issues with my
previous random record generating code?
ie, can i open the DB to get a record count without SELECTing anything?
For the 15th time, YOU DON'T NEED A RECORD COUNT!
You don't NEED oRs.Move. Using "TOP 1" you will only get a single record
back.
Jimmy wrote:
ok i got ya...
so is there a way to "oRS.Move" to a particular record without having
to do it this way?
ie, can i open the DB to get a record count without SELECTing
anything?
"Bob Barrows [MVP]" <re******@NOyah oo.SPAMcomwrote in message
news:%2******** ********@TK2MSF TNGP05.phx.gbl. ..
>Jimmy wrote:
>>this is what i have working so far... tell me what you think:
oRS.Open "SELECT EMAIL_ADDRESS FROM TABLE1", oConn, adOpenStatic,
adLockReadOnl y
Randomize()
randNum = CInt((oRS.Recor dCount - 1) * Rnd)
Response.Writ e("RecordCoun t: " & oRS.RecordCount & "<br><br>")
oRS.Move randNum
>>>
seems like it works perfectly... do you see any issues?
Yes. You're retrieving all the records from the database when you
only need one of them. Not a very efficient use of network or server
resources.
--
Microsoft MVP -- ASP/ASP.NET
Please reply to the newsgroup. The email account listed in my From
header is my spam trap, so I don't check it very often. You will get
a quicker response by posting to the newsgroup.
--
Microsoft MVP -- ASP/ASP.NET
Please reply to the newsgroup. The email account listed in my From
header is my spam trap, so I don't check it very often. You will get a
quicker response by posting to the newsgroup.
no, the confusion was because i had SQL Express at first but then was forced to go with Access. so i didnt know what would still work. it has been pointed out that this code is bad:
<%
Dim oConn, oRS, randNum
Set oConn=Server.Cr eateObject("ADO DB.Connection")
Set oRS=Server.Crea teObject("ADODB .recordset")
oConn.Provider= "Microsoft.Jet. OLEDB.4.0"
oConn.Open Server.MapPath( "temp.mdb")
oRS.Open "SELECT EMAIL_ADDRESS FROM TABLE1", oConn, adOpenStatic, adLockReadOnly
Randomize()
randNum = CInt((oRS.Recor dCount - 1) * Rnd)
Response.Write( "RecordCoun t: " & oRS.RecordCount & "<br><br>")
oRS.Move randNum
Response.Write oRS("EMAIL_ADDR ESS")
oRS.close
oConn.close
Set oConn = nothing
Set oRS = nothing
%>
so i wanted to know if the "TOP 1" method could be done in access, and maybe see an example based on what i have here.
"Aaron Bertrand [SQL Server MVP]" <te*****@dnartr eb.noraawrote in message news:OD******** *****@TK2MSFTNG P06.phx.gbl...
What, this?
>>randNum = (CInt((recordco unt-1) * Rnd) + 1)
Again, you need to show us what you are doing with randNum before we can
comment.
But yes, as we've already suggested, there are issues.
My guess is you are going to say
sql = "SELECT EmailAddress FROM Table1 WHERE PK = " & RandNum
And like I already commented, this won't work reliably. Never mind the
unnecessary roundtrip to count the number of rows in the table.
I think you need to stop theorizing code and deal with this when you can
actually test it against a real database and understand the differences and
what we are talking about. Until then it seems you are hellbent on just
doing it your way and ignoring our advice.
A
"Jimmy" <j@j.jwrote in message
news:Od******** ********@TK2MSF TNGP06.phx.gbl. ..
>thank you.
im currently testing with an access db. do you see any issues with my
previous random record generating code?
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