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https://dev.mysql.com/string-type-syntax.html
CHAR(0) is also quite nice when you need a column that can take only two values: A column that is defined as CHAR(0) NULL occupies only one bit and can take only the values NULL and '' (the empty string). A string object that can have only one ...
https://dev.mysql.com/sys-innodb-lock-waits.html
locked_table_partition The name of the locked partition, if any; NULL otherwise. locked_table_subpartition The name of the locked subpartition, if any; NULL otherwise. This field reports NULL if the session that issued the blocking query becomes ...
https://dev.mysql.com/sys-ps-is-consumer-enabled.html
Returns YES or NO to indicate whether a given Performance Schema consumer is enabled, or NULL if the argument is NULL. (Prior to MySQL 8.0.18, the function returns NULL if the argument is not a valid consumer name.) This function accounts for the ...If the argument is not a valid consumer name, an error ...
https://dev.mysql.com/where-optimization.html
This is also done for any NOT NULL expression when used with only one table. A table that is used with a WHERE clause on a PRIMARY KEY or a UNIQUE index, where all index parts are compared to constant expressions and are defined as NOT NULL. This ...
https://dev.mysql.com/writing-daemon-plugins.html
A daemon plugin is a simple type of plugin used for code that should be run by the server but that does not communicate with it. This section describes how to write a daemon server plugin, using the example plugin found in the plugin/daemon_example ...
https://dev.mysql.com/writing-keyring-plugins.html
The general descriptor also refers to keyring_system_variables, a structure that exposes a system variable to the SHOW VARIABLES statement: static struct st_mysql_sys_var *keyring_system_variables[]= { MYSQL_SYSVAR(data), NULL }; The keyring_init ...
https://dev.mysql.com/writing-password-validation-plugins.html
This section describes how to write a server-side password-validation plugin. The instructions are based on the source code in the plugin/password_validation directory of MySQL source distributions. The validate_password.cc source file in that ...
https://dev.mysql.com/accounts-table.html
This is NULL for an internal thread, or for a user session that failed to authenticate. This is NULL for an internal thread, or for a user session that failed to authenticate. The accounts table contains a row for each account that has connected to ...
https://dev.mysql.com/arithmetic-functions.html
(See Section 11.1, “Numeric Data Types”.) / Division: mysql> SELECT 3/5; -> 0.60 Division by zero produces a NULL result: mysql> SELECT 102/(1-1); -> NULL A division is calculated with BIGINT arithmetic only if performed in a context where its ... Table 12.8 Arithmetic Operators Name Description %, MOD Modulo operator * Multiplication operator + Addition operator - Minus operator - Change the sign of the argument / Division operator DIV Integer division The usual arithmetic operators are ...
https://dev.mysql.com/audit-log-filter-definitions.html
The following list describes the permitted predefined functions for function items: audit_log_exclude_accounts_is_null() Checks whether the audit_log_exclude_accounts system variable is NULL. For information about using JSON data in MySQL, see ...
Document created the 26/06/2006, last modified the 26/10/2018
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