https://dev.mysql.com/getting-unique-id.html
It is not even changed if you update another AUTO_INCREMENT column with a nonmagic value (that is, a value that is not NULL and not 0). If you store an explicit value other than NULL or 0, it does not affect the value returned by LAST_INSERT_ID().
https://dev.mysql.com/gis-format-conversion-functions.html
If the options argument is NULL, the return value is NULL. MySQL supports the functions listed in this section for converting geometry values from internal geometry format to WKT or WKB format, or for swapping the order of X and Y coordinates.
https://dev.mysql.com/gis-polygon-property-functions.html
Unless otherwise specified, functions in this section handle their arguments as follows: If any argument is NULL or any geometry argument is an empty geometry, the return value is NULL. If a geometry is empty, the return value is 0 rather than NULL.
https://dev.mysql.com/gis-wkt-functions.html
If the options argument is NULL, the return value is NULL. These functions take as arguments a Well-Known Text (WKT) representation and, optionally, a spatial reference system identifier (SRID). For a description of WKT format, see Well-Known Text ...
https://dev.mysql.com/innodb-fulltext-index.html
If you want to create your own FTS_DOC_ID column, the column must be defined as BIGINT UNSIGNED NOT NULL and named FTS_DOC_ID (all uppercase), as in the following example: Note The FTS_DOC_ID column does not need to be defined as an AUTO_INCREMENT ... FULLTEXT indexes are created on text-based columns (CHAR, VARCHAR, or TEXT columns) to help speed up queries and DML operations on data contained within those columns, omitting any words that are defined as ...
https://dev.mysql.com/innodb-memcached-internals.html
The mapped key must be a non-Null CHAR or VARCHAR type. There is no length restriction and the value can be NULL. flags: Must be mapped to an INTEGER of at least 32-bits and can be NULL. If there are fewer delimited values than mapped columns, ...
https://dev.mysql.com/innodb-metrics-table.html
row *************************** NAME: dml_inserts SUBSYSTEM: dml COUNT: 3 MAX_COUNT: 3 MIN_COUNT: NULL AVG_COUNT: 0.046153846153846156 COUNT_RESET: 3 MAX_COUNT_RESET: 3 MIN_COUNT_RESET: NULL AVG_COUNT_RESET: NULL TIME_ENABLED: 2014-12-04 14:18:28 ...
https://dev.mysql.com/innodb-virtual-table.html
CREATE TABLE `t1` ( `a` int(11) DEFAULT NULL, `b` int(11) DEFAULT NULL, `c` int(11) GENERATED ALWAYS AS (5) VIRTUAL ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4; However, metadata for such a column does appear in the INNODB_COLUMNS table. The ...
https://dev.mysql.com/locking-service-c-interface.html
If specified as NULL, the handle for the current thread is used. lock_names: An array of null-terminated strings that provides the names of the locks to acquire. If specified as NULL, the handle for the current thread is used. This section ...
https://dev.mysql.com/merge-storage-engine.html
The column of the underlying table and the MERGE table can be NULL. The MERGE storage engine, also known as the MRG_MyISAM engine, is a collection of identical MyISAM tables that can be used as one. “Identical” means that all tables have ...
