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https://dev.mysql.com/doc/refman/8.4/en/constraint-foreign-key.html
The available referential actions are RESTRICT, CASCADE, SET NULL, and NO ACTION (the default). Foreign keys let you cross-reference related data across tables, and foreign key constraints help keep this spread-out data consistent. MySQL supports ...
https://dev.mysql.com/doc/refman/8.4/en/csv-storage-engine.html
The CSV storage engine stores data in text files using comma-separated values format. The CSV storage engine is always compiled into the MySQL server. To examine the source for the CSV engine, look in the storage/csv directory of a MySQL source ...
https://dev.mysql.com/doc/refman/8.4/en/example-maximum-column-group-row.html
Task: For each article, find the dealer or dealers with the most expensive price. Other possibilities for solving the problem are to use an uncorrelated subquery in the FROM clause, a LEFT JOIN, or a common table expression with a window function.
https://dev.mysql.com/doc/refman/8.4/en/gis-property-functions.html
Such functions return NULL if the argument is of an incorrect geometry type. For example, the ST_Area() polygon function returns NULL if the object type is neither Polygon nor MultiPolygon. Each function that belongs to this group takes a geometry ...
https://dev.mysql.com/doc/refman/8.4/en/group-replication-adding-instances.html
At this point, the group has one member in it, server s1, which has some data in it. It is now time to expand the group by adding the other two servers configured previously. 20.2.1.6.1 Adding a Second Instance In order to add a second instance, ...
https://dev.mysql.com/doc/refman/8.4/en/group-replication-bootstrap.html
mysql> CREATE DATABASE test; mysql> USE test; mysql> CREATE TABLE t1 (c1 INT PRIMARY KEY, c2 TEXT NOT NULL); mysql> INSERT INTO t1 VALUES (1, 'Luis'); Check the content of table t1 and the binary log. The process of starting a group for the first ...
https://dev.mysql.com/doc/refman/8.4/en/host-cache.html
Initially, the host name is set to NULL and the flag is false. For permanent failures, the host name remains NULL and the validation flag is set to true. The MySQL server maintains an in-memory host cache that contains information about clients: IP ...
https://dev.mysql.com/doc/refman/8.4/en/index-hints.html
row *************************** id: 1 select_type: DELETE table: t1 partitions: NULL type: range possible_keys: col2 key: col2 key_len: 5 ref: NULL rows: 72 filtered: 11.11 Extra: Using where 1 row in set, 1 warning (0.00 sec) . Index hints give ...
https://dev.mysql.com/doc/refman/8.4/en/information-schema-innodb-buffer-page-lru-table.html
The column is NULL if the server has not yet accessed the table. The INNODB_BUFFER_PAGE_LRU table provides information about the pages in the InnoDB buffer pool; in particular, how they are ordered in the LRU list that determines which pages to ...
https://dev.mysql.com/doc/refman/8.4/en/information-schema-innodb-foreign-table.html
0 = ON DELETE/UPDATE RESTRICT, 1 = ON DELETE CASCADE, 2 = ON DELETE SET NULL, 4 = ON UPDATE CASCADE, 8 = ON UPDATE SET NULL, 16 = ON DELETE NO ACTION, 32 = ON UPDATE NO ACTION. For related usage information and examples, see Section 17.15.3, ...