I think the reason nobody has replied is that the term "row number" does not really have any meaning in a DBMS. How the database stores rows inteneally is the DBMS's private business, and should not be visible to you. I think it is true that MySQL does not *have* an internal row number, so there is nothing to skip by. All it stores in MyISAM table is file offsets. However, even if I am wrong, it doesn't matter: that is an internal implementation detail and should not be visible to you.
However, if I read you rightly, what you want it to extract a random tenth of your table. You could do this by something like SELECT <columns> FROM <table> ORDER BY rand() LIMIT <table size / 10> ; Joćo Borsoi Soares <[EMAIL PROTECTED]> wrote on 23/11/2004 11:30:26: > No body has answered my question so far. Does that mean there is no way > to retrieve current row numbers in a query or no way to retrieve results > jumping steps? > > I would appreciate any help. > > Thanks, > Joao. > > -----Mensagem encaminhada----- > > From: Joćo Borsoi Soares <[EMAIL PROTECTED]> > > To: [EMAIL PROTECTED] <[EMAIL PROTECTED]> > > Subject: row numbers, jumping rows > > Date: Sun, 21 Nov 2004 11:23:41 -0200 > > > > Hello list, > > > > I wonder if someone could help me to get the fastest result on my query. > > I need to classify one entity, according to a specific attribute (let's > > call it X), looking at a sample extracted from a database table. > > First I need to sort my sample ordered by a specific table field (X). > > Then I should divide my sorted sample in 10 equal groups (same number of > > rows). Finally, I should classify my entity (1 to 10), finding out at > > which group its attribute X fits in. > > > > Let me explain my thoughts. First I should make a "SELECT COUNT(*).." to > > find the total number of rows in my sample. Then I make queries using > > LIMIT until I find which group the X attribute fits in. In the worst > > case I will have to do 10 queries. Which I think should take too long in > > my case. > > > > I wanted to make it in only one query. It could be possible if I could > > make a query which returns result jumping rows, like "STEP N" where "N" > > could be the number of items in each group. Is there anything in mysql > > that can give me that? I also thought if I could have the row numbers in > > the query result, I could solve it with a simple condition like, "WHERE > > rowNum % N = 0". > > > > Any ideas? > > > > Thanks. > > > > > > > > > -- > MySQL General Mailing List > For list archives: http://lists.mysql.com/mysql > To unsubscribe: http://lists.mysql.com/[EMAIL PROTECTED] > -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/[EMAIL PROTECTED]
