Oracle's PL/SQL questions http://oracleinterviews.com Find all the answers to your questions on PL/SQL questions. Thu, 12 Nov 2009 02:51:44 +0000 http://backend.userland.com/rss092 en Difference between post query and pre query? post query will fire for every row that it fetched pre query will fire only once http://oracleinterviews.com/2007/09/17/difference-between-post-query-and-pre-query/ What is clustered index? In clustered index rows are stored together based on clustered key values http://oracleinterviews.com/2007/09/17/what-is-clustered-index/ What are referenced object? copy of an object maintains link to the source object. any changes to source object same are done reflected in the reference object http://oracleinterviews.com/2007/09/17/what-are-referenced-object/ Steps involved in db shutdown? shutdown the instance,dismount the db,close the db http://oracleinterviews.com/2007/09/17/steps-involved-in-db-shutdown/ Steps involved in db startup? start an instance,mount the db,open the db http://oracleinterviews.com/2007/09/17/steps-involved-in-db-startup/ What is referential integrity? A rule defined on a column (or set of columns) in one table that allows the insert or update of a row only if the value for the column or set of columns (the dependent value) matches a value in a column of a related table (the referenced value). examples PK ... http://oracleinterviews.com/2007/09/17/what-is-referential-integrity/ Types of db links? Private created on behalf of a specific user Public created for a special user group Network created and managed by network domain service. http://oracleinterviews.com/2007/09/17/types-of-db-links/ Types of segments? data segment each non cluster/cluster table has a data segment.Tables data is stored in the extent of its data segment index segment each index has index segment to store its data rollback segment db contains one or more rollback segments to temporarily store undo information temporary segment temporary segments are created when SQL statements ... http://oracleinterviews.com/2007/09/17/types-of-segments/ Why use an index? index gives faster access to data blocks in a table. http://oracleinterviews.com/2007/09/17/why-use-an-index/ Difference between data block,extent and segment? data block is the smallest unit of storage for a db object. when objects grow they take additional storage of adjacent data blocks.These grouping of adjacent data blocks is called extent. All the extents that an object takes when grouped together is called segment http://oracleinterviews.com/2007/09/17/difference-between-data-blockextent-and-segment/