This means that if you kill DELETE [LOW_PRIORITY | QUICK] FROM table_name [WHERE where_definition] [ORDER BY ...] [LIMIT rows] or DELETE [LOW_PRIORITY | QUICK] table_name[.*] [,table_name[.*] ...] FROM table-references [WHERE where_definition] or DELETE [LOW_PRIORITY | QUICK] FROM table_name[.*], [table_name[.*] ...] USING table-references [WHERE where_definition] clause will return zero as the number of affected records.
If you really want to know how many records are deleted when you are deleting all rows, and are willing to suffer a speed penalty, you can use a is faster. The first multi-table delete format is supported starting from My SQL 4.0.0.
Providing values only for the few first columns is possible.
If the index consists of several parts (spans over several columns), the values are specified in comma-separated lists.
As the resulting file doesn’t have to conform to the SQL syntax, nothing else need be escaped. or INSERT [LOW_PRIORITY | DELAYED] [IGNORE] [INTO] tbl_name SET col_name=expression, col_name=expression, ...
Here is an example of getting a file in the format used by many old programs:table_reference, table_reference table_reference [CROSS] JOIN table_reference table_reference INNER JOIN table_reference join_condition table_reference STRAIGHT_JOIN table_reference table_reference LEFT [OUTER] JOIN table_reference join_condition table_reference LEFT [OUTER] JOIN table_reference table_reference NATURAL [LEFT [OUTER JOIN table_reference table_reference RIGHT [OUTER] JOIN table_reference join_condition table_reference RIGHT [OUTER] JOIN table_reference table_reference NATURAL [RIGHT [OUTER]] JOIN table_reference HANDLER tbl_name OPEN [ AS alias ] HANDLER tbl_name READ index_name (value1,value2,...) [ WHERE ... is that inserts from many clients are bundled together and written in one block.
A derived table that is embedded in the query is sometimes called an unnamed derived table.]]
The tipical command for creating a normal view is: CREATE VIEW my_view AS SELECT In order to create the equivalent to a materialized view you create a table with the same name instead of a view.
In My SQL 5.7, we have enhanced the optimizer so that derived tables and views are handled more consistently.
Just to recap: A derived table is a subquery that can take the place of a table in the FROM clause of an SQL statement.
These two query sets are thus equivalent: For a long time, there has been a difference in the handling of views and derived tables: While it has been possible to merge views into the outer query, a derived table would always be materialized and accessed as a temporary table in the outer query.
This is costly for two reasons: creating and reading the materialized temporary table takes time, and it prohibits pushing down conditions from the outer query to the derived table.