intimidating haircuts - Updating rows in sql

You can use the schema qualifier to select from a table, view, or materialized view in a schema other than your own. The object can be a table, view, materialized view, or subquery.

Updating rows in sql

if you want the database to return only one copy of each set of duplicate rows selected. Duplicate rows are those with matching values for each expression in the select list.

Specify the object name followed by a period and the asterisk to select all columns from the specified table, view, or materialized view.

A searched update statement depends on the table being updated, all of its conglomerates (units of storage such as heaps or indexes), all of its constraints, and any other table named in the WHERE clause or SET expressions.

A CREATE or DROP INDEX statement or an ALTER TABLE statement for the target table of a prepared searched update statement invalidates the prepared searched update statement.

The query name is visible to the main query and to all subsequent subqueries.

For recursive subquery factoring, the query name is even visible to the subquery that defines the query name itself.

Adding values in the middle of an index is always slower.

You can think of it like appending to an address book: Mr Z can just be added to the last page, while you'll have to find space in the middle for Mr M.

If columns were specified in the FOR UPDATE clause of the SELECT statement used to generate the cursor, only those columns can be updated.

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