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In the Oracle Database, TRUNCATE is implicitly preceded and followed by a commit operation. (This may also be the case in MySQL , when using a transactional storage engine.) Typically, TRUNCATE TABLE quickly deletes all records in a table by deallocating the data pages used by the table.
DELETE requires a shared table lock; Triggers fire; DELETE can be used in the case of: database link; DELETE returns the number of records deleted; Transaction log - DELETE needs to read records, check constraints, update block, update indexes, and generate redo / undo. All of this takes time, hence it takes time much longer than with TRUNCATE
The DROP statement is distinct from the DELETE and TRUNCATE statements, in that DELETE and TRUNCATE do not remove the table itself. For example, a DELETE statement might delete some (or all) data from a table while leaving the table itself in the database, whereas a DROP statement removes the entire table from the database.
SQL includes operators and functions for calculating values on stored values. SQL allows the use of expressions in the select list to project data, as in the following example, which returns a list of books that cost more than 100.00 with an additional sales_tax column containing a sales tax figure calculated at 6% of the price.
SELECT list is the list of columns or SQL expressions to be returned by the query. This is approximately the relational algebra projection operation. AS optionally provides an alias for each column or expression in the SELECT list. This is the relational algebra rename operation. FROM specifies from which table to get the data. [3]
"In reality," he said, "foodborne illnesses can lead to severe and long-lasting health issues, hospitalization or even death, especially for vulnerable populations like the immunocompromised ...
A new study says that air pollution — specifically, the kind caused by car exhaust — may be a significant cause of rising rates of autism in children.. Exposure to nitric oxide (NO)— which ...
In computer programming, create, read, update, and delete (CRUD) are the four basic operations (actions) of persistent storage. [1] CRUD is also sometimes used to describe user interface conventions that facilitate viewing, searching, and changing information using computer-based forms and reports .