https://dev.mysql.com/select-into.html
If the FIELDS ESCAPED BY character is empty, no characters are escaped and NULL is output as NULL, not \N. INTO form of SELECT enables a query result to be stored in variables or written to a file: SELECT ... Column and line terminators can be ...
https://dev.mysql.com/storage-engines.html
row *************************** Engine: BLACKHOLE Support: YES Comment: /dev/null storage engine (anything you write to it disappears) Transactions: NO XA: NO Savepoints: NO *************************** 5. Blackhole: The Blackhole storage engine ...
https://dev.mysql.com/sys-diagnostics.html
Use NULL to collect data for the default of 60 seconds. Creates a report of the current server status for diagnostic purposes. This procedure disables binary logging during its execution by manipulating the session value of the sql_log_bin system ...
https://dev.mysql.com/sys-processlist.html
db The default database for the thread, or NULL if there is none. current_statement The statement the thread is executing, or NULL if it is not executing any statement. They provide more complete information than the SHOW PROCESSLIST statement and ...
https://dev.mysql.com/sys-ps-is-thread-instrumented.html
Returns YES or NO to indicate whether Performance Schema instrumentation for a given connection ID is enabled, UNKNOWN if the ID is unknown, or NULL if the ID is NULL. This is a value of the type given in the PROCESSLIST_ID column of the ...
https://dev.mysql.com/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/table-waits-summary-tables.html
A value of NULL means that table I/O used no index. The following sections describe the table I/O and lock wait summary tables: table_io_waits_summary_by_index_usage: Table I/O waits per index table_io_waits_summary_by_table: Table I/O waits per ...
https://dev.mysql.com/thread-information.html
db is the default database for the thread, or NULL if none is selected. Info contains the text of the statement being executed by the thread, or NULL if it is not executing one. When you are attempting to ascertain what your MySQL server is doing, ...
https://dev.mysql.com/user-defined-functions-table.html
The value is NULL if the function was registered by a CREATE FUNCTION statement and is in the process of unloading. The value is NULL if the UDF was registered using a server component service rather than by a CREATE FUNCTION statement. The ...
https://dev.mysql.com/user-variables.html
User variables can be assigned a value from a limited set of data types: integer, decimal, floating-point, binary or nonbinary string, or NULL value. If you refer to a variable that has not been initialized, it has a value of NULL and a type of ...