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Showing posts with label Truncate and Delete. Show all posts
Showing posts with label Truncate and Delete. Show all posts

Tuesday, November 20, 2012

Truncate and Delete

Generally Delete command removes the rows from a table based on some where condition. whereas Truncate removes all the rows from a table.

Truncate

  • Truncate is faster and uses fewer system and transaction log resources than Delete. 
  • You cannot use  Truncate Table on a table referenced by a FOREIGN KEY constraint.
  • Truncate is a DDL Command.
  • Truncate resets the identity of the table.
  • Truncate removes all the rows from a table, but the table structure, its columns, constraints, indexes and so on remains. The counter used by an identity for new rows is reset to the seed for the column.
  • Truncate cannot be rolled back unless it is used in TRANSACTION. OR TRUNCATE can be rolled back when used with BEGIN … END TRANSACTION using T-SQL.
  • Truncate removes the data by deallocating the data pages used to store the table’s data, and only the page deallocations are recorded in the transaction log.
Delete
  • Delete removes rows one at a time and records an entry in the transaction log for each deleted row.
  • Delete does not reset the identity of the table.
  • Delete is DML Command.
  • Delete can be rolled back.
  • Delete does not reset Identity property of the table.
  • Delete can be used with or without a WHERE clause.
  • Delete activates Triggers if defined on table.