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https://dev.mysql.com/doc/refman/8.4/en/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/doc/refman/8.4/en/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/doc/refman/8.4/en/system-schema.html
row *************************** CATALOG_NAME: def SCHEMA_NAME: mysql DEFAULT_CHARACTER_SET_NAME: utf8mb4 DEFAULT_COLLATION_NAME: utf8mb4_0900_ai_ci SQL_PATH: NULL DEFAULT_ENCRYPTION: NO *************************** 2. row *************************** ...It contains tables that store information required by the MySQL server as it ...
https://dev.mysql.com/doc/refman/8.4/en/upgrading-from-previous-series.html
Setting server variables equal to SQL NULL on the command line is not supported. In MySQL 8.4, setting any of these to NULL is specifically disallowed, and attempting to do is rejected with an error. Before upgrading to MySQL 8.4, review the ...
https://dev.mysql.com/doc/refman/8.4/en/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/doc/relnotes/mysql/8.4/en/news-8-4-0.html
(Bug #35183686) InnoDB: Results for SHOW ENGINE INNODB STATUS showed an invalid value (NULL) as the name of the first thread in the File IO section. (Bug #36210740) Some queries using NULLIF() and EXCEPT raised an assertion in set_typelib(). (Bug ...
https://dev.mysql.com/doc/relnotes/mysql/8.4/en/news-8-4-5.html
(Bug #37370439) An UPDATE subsequent to an INSERT affecting a table which had a BEFORE INSERT trigger was sometimes rejected with a null value error when the INSERT had set a NOT NULL column to NULL, even though this should have been allowed by the ...(Bug #37570206) Audit Log Notes <COMMAND_CLASS> was not populated for ...
https://dev.mysql.com/doc/mysql-enterprise-backup/8.4/en/meb-scheduled-backups.html
Outputs from the stderr and stdout streams are redirected to /dev/null/, so they will not invoke other actions on the part of the Cron server (for example, email notifications to the user). Maintaining a regular backup schedule is an important ...
https://dev.mysql.com/doc/c-api/8.4/en/mysql-fetch-field.html
For metadata-optional connections, this function returns NULL when the resultset_metadata system variable is set to NONE. NULL if no columns are left or the result set has no metadata. MYSQL_FIELD * mysql_fetch_field(MYSQL_RES *result) Description ...
https://dev.mysql.com/doc/c-api/8.4/en/mysql-info.html
String format: Records: 3 Duplicates: 0 Warnings: 0 LOAD DATA String format: Records: 1 Deleted: 0 Skipped: 0 Warnings: 0 ALTER TABLE String format: Records: 3 Duplicates: 0 Warnings: 0 UPDATE String format: Rows matched: 40 Changed: 40 Warnings: 0 ... const char * mysql_info(MYSQL *mysql) Description Retrieves a string providing information about the most recently executed statement, but only for the statements listed ...