https://dev.mysql.com/cost-model.html
Any non-NULL cost estimate specified in the tables takes precedence over the corresponding compiled-in default cost constant. Any NULL estimate indicates to the optimizer to use the compiled-in default. It is also easy to revert to a default by ...
https://dev.mysql.com/enterprise-encryption-functions.html
If the arguments are not suitable to permit a function to perform the requested operation, it returns NULL or 0 as appropriate. MySQL Enterprise Encryption functions have these general characteristics: For arguments of the wrong type or an ...
https://dev.mysql.com/events-transactions-current-table.html
END_EVENT_ID This column is set to NULL when the event starts and updated to the thread current event number when the event ends. If an event is produced from an instrument that has TIMED = NO, timing information is not collected, and TIMER_START, ...The table stores one row per thread showing the current status of the thread's most recent monitored transaction event, so there is no system variable for configuring the table ...
https://dev.mysql.com/example-auto-increment.html
For example: INSERT INTO animals (id,name) VALUES(0,'groundhog'); If the column is declared NOT NULL, it is also possible to assign NULL to the column to generate sequence numbers. For example: INSERT INTO animals (id,name) VALUES(NULL,'squirrel'); ...You can also explicitly assign 0 to the column to generate sequence numbers, unless the NO_AUTO_VALUE_ON_ZERO SQL mode is ...
https://dev.mysql.com/func-op-summary-ref.html
GTID_SUBTRACT() Return all GTIDs in set that are not in subset. JSON_CONTAINS() Whether JSON document contains specific object at path JSON_CONTAINS_PATH() Whether JSON document contains any data at path JSON_DEPTH() Maximum depth of JSON document ...
https://dev.mysql.com/group-by-functional-dependence.html
A UNIQUE index over a NOT NULL column could be used instead of a primary key and the same functional dependence would apply. As with the previous example, a UNIQUE key over NOT NULL columns could be used instead of a primary key. If in the join ...
https://dev.mysql.com/replication-gtids-concepts.html
A global transaction identifier (GTID) is a unique identifier created and associated with each transaction committed on the server of origin (the master). This identifier is unique not only to the server on which it originated, but is unique across ...
https://dev.mysql.com/rewriter-query-rewrite-plugin-usage.html
row *************************** id: 1 pattern: SELECT ? pattern_database: NULL replacement: SELECT ? + 1 enabled: YES message: NULL pattern_digest: NULL normalized_pattern: NULL The rule specifies a pattern template indicating which SELECT ... To ...
https://dev.mysql.com/routines-table.html
If the routine is a stored procedure, this value is NULL. If the routine is a stored procedure, this value is NULL. If the routine is a stored procedure, this value is NULL. If the routine is a stored procedure, this value is NULL. If the routine is ... The ROUTINES table provides information about stored routines (stored procedures and stored ...
https://dev.mysql.com/selecting-all.html
For example, you may happen to think that the birth date for Bowser doesn't seem quite right. Consulting your original pedigree papers, you find that the correct birth year should be 1989, not 1979. Fix only the erroneous record with an UPDATE ...
