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 |
|
Grifter
Constraint Violating Yak Guru
274 Posts |
 Posted - 2012-07-05 : 04:26:49
|
| Hi I have a query like this:[code]select a, b, cfrom tablea a1where a1.a IN (select a2.a from table2 a2)[code]And I have been told by another developer I should put an index on the a2.a column as it will do a full table scan.I do not have much experience with indexes at all and not sure what type of index I need to put in?Can someone tell me what type of index and a basic syntax to implement it, or a way to do it in management studio? Reading up on clustered and non-clustered and after reading it doesn't make any sense really to me what it is I need.ThanksG |
|
|
RickD
Slow But Sure Yak Herding Master
3608 Posts |
Posted - 2012-07-05 : 05:00:47
|
| Depends what you already have on the table? Do you have a Primary Key or Clustered Index defined already?The basic syntax is available in BoL, which you can get to by the Help menu in SSMS.Look up CREATE INDEX |
 |
|
|
Grifter
Constraint Violating Yak Guru
274 Posts |
Posted - 2012-07-05 : 05:15:04
|
| I don't see any other indexes on it, primary key etc. and checked sys.index table and there is no index id for this table. I'm assuming bol = books online?G |
|
|
|
nigelrivett
Master Smack Fu Yak Hacker
3385 Posts |
Posted - 2012-07-05 : 05:44:30
|
| Consider an index on a1.a including b,c - or clustered index on anon-clustered index on a2.aDepends on the size of the tables and column data as to how effective this will be or whether it will make a difference.==========================================Cursors are useful if you don't know sql.SSIS can be used in a similar way.Beer is not cold and it isn't fizzy. |
|
|
|
|
|
|
Help with an index