Please start any new threads on our new
site at https://forums.sqlteam.com. We've got lots of great SQL Server
experts to answer whatever question you can come up with.
| Author |
Topic |
|
gavakie
Posting Yak Master
221 Posts |
 Posted - 2011-06-03 : 17:00:41
|
| I have query ive written where i pull out column a which is all distinct and a grouping column, that is either a 1,2,3I need to pull 10% of the results at random from the group but make sure there is an even distribution of the three options in the second column.Any ideas? |
|
|
sunitabeck
Master Smack Fu Yak Hacker
5155 Posts |
Posted - 2011-06-03 : 17:57:35
|
If you are on SQL 2008, you can use TABLESAMPLE (http://msdn.microsoft.com/en-us/library/ms189108.aspx ). However, the rows returned may not be truly random. If you do want truly random, select top 10 percent, but using an order by clause that involves newid function and a column in your table, so that the newid function will be invoked per row. For example:select top 10 percent *from yourTable order by RAND(CHECKSUM(NEWID())%1000000000 + AColumnINTheTable) In both the above cases, the distribution will be roughly proportional to the distribution of the grouping column in your table. |
 |
|
|
|
|
|
Random Numbers