The below command will rebuild all indexes on a database.
We need to run the below command in the context of each database that is of interest.
sp_MSForEachTable "DBCC DBREINDEX('?')"
The below command is for updating the statistics with full scan.
We also need to run this command in the context of each database.
sp_MSForEachTable "UPDATE STATISTICS ? with fullscan" 
the following scripts helps in finding top 5 missing indexes using the new feature of DMV available in SQl Server 2005
2007-07-19 (first published: 2006-10-23)
5,361 reads
Recent installments of our SQL Server 2005 Express Edition series have been discussing its implementation of Full Text Indexing. This article focuses on data searches, which leverage existing indexes, taking into account such features as noise words and thesaurus files.
2010-01-07
2,426 reads
Gets single-column and cumulative-column selectivity stats and @Top largest dupe sets for each cumulative column stepping for a set of one or more columns for a table.
2009-05-03 (first published: 2008-08-01)
2,110 reads
Searches database-wide for multiple indexes in the same table which has the same column as the first seek key. Optionally limits to LIKE wildcard patterns of table and schema names.
2008-10-17 (first published: 2008-08-01)
3,286 reads
Reports index stats, index size+rows, member seek + include columns as two comma separated output columns, and index usage stats for one or more tables and/or schemas.
2012-12-27 (first published: 2008-08-01)
7,932 reads