https://dev.mysql.com/derived-tables.html
row *************************** id: 1 select_type: PRIMARY table: <derived2> partitions: NULL type: system possible_keys: NULL key: NULL key_len: NULL ref: NULL rows: 1 filtered: 100.00 Extra: NULL *************************** 2. row ...For ...
https://dev.mysql.com/glossary.html
It provides useful information for the query optimizer, because the column is known to be not null and with unique values. A column can be subject to a unique constraint, a NOT NULL constraint, or both. See Also cardinality, foreign key, index, NOT ... These terms are commonly used in information about the MySQL database ...
https://dev.mysql.com/partitioning-range.html
A table that is partitioned by range is partitioned in such a way that each partition contains rows for which the partitioning expression value lies within a given range. Ranges should be contiguous but not overlapping, and are defined using the ...
https://dev.mysql.com/json.html
Prior to MySQL 8.0.13, a JSON column cannot have a non-NULL default value. A path that does not exist in the document (evaluates to nonexistent data) evaluates to NULL. $[3] evaluates to NULL (it refers to the fourth array element, which does not ...
https://dev.mysql.com/mysql-cluster-programs-ndb-desc.html
ndb_desc provides a detailed description of one or more NDB tables. Usage ndb_desc -c connection_string tbl_name -d db_name [options] ndb_desc -c connection_string index_name -d db_name -t tbl_name Additional options that can be used with ndb_desc ...
https://dev.mysql.com/server-system-variables.html
If explicit_defaults_for_timestamp is disabled, the server enables the nonstandard behaviors and handles TIMESTAMP columns as follows: TIMESTAMP columns not explicitly declared with the NULL attribute are automatically declared with the NOT NULL ...
https://dev.mysql.com/group-by-functions.html
The result type depends on whether the function argument values are evaluated as binary strings or numbers: Binary-string evaluation occurs when the argument values have a binary string type, and the argument is not a hexadecimal literal, bit ...
https://dev.mysql.com/innodb-information-schema-metrics-table.html
Because no DML operations have been performed, the counter values are zero or NULL. row *************************** NAME: dml_inserts SUBSYSTEM: dml COUNT: 0 MAX_COUNT: 0 MIN_COUNT: NULL AVG_COUNT: 0 COUNT_RESET: 0 MAX_COUNT_RESET: 0 ... The ...
https://dev.mysql.com/bit-functions.html
For &, |, and ^ bit operations, the result type depends on whether the arguments are evaluated as binary strings or numbers: Binary-string evaluation occurs when the arguments have a binary string type, and at least one of them is not a hexadecimal ...(The BIT_AND(), BIT_OR(), and BIT_XOR() aggregate functions are described in Section 12.20.1, “Aggregate (GROUP BY) Function Descriptions”.) Prior to MySQL 8.0, bit functions and operators required BIGINT (64-bit integer) arguments and returned BIGINT values, so they had a maximum range of 64 ...
https://dev.mysql.com/plugin-data-structures.html
init: A once-only initialization function, or NULL if there is no such function. deinit: A once-only deinitialization function, or NULL if there is no such function. status_vars: A pointer to a structure for status variables associated with the ...
