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https://dev.mysql.com/writing-authentication-plugins.html
A value of NULL means “any plugin.” In the latter case, whatever plugin the client uses will do. The value is represented as a string at most MYSQL_USER_NAME_LENGTH bytes long, plus a terminating null. external_user: The server sets this to the ... MySQL supports pluggable authentication, in which plugins are invoked to authenticate client ...
https://dev.mysql.com/get-diagnostics.html
Within a stored procedure p(), we attempt to insert two values into a table that contains a TEXT NOT NULL column. The first value is a non-NULL string and the second is NULL. The column prohibits NULL values, so the first insert succeeds but the ...
https://dev.mysql.com/innodb-information-schema-examples.html
requesting trx id requested lock id blocking trx id blocking lock id A4 A4:1:3:2 A3 A3:1:3:2 A5 A5:1:3:2 A3 A3:1:3:2 A5 A5:1:3:2 A4 A4:1:3:2 When identifying blocking transactions, a NULL value is reported for the blocking query if the session that ... Note This section describes locking information as exposed by the Performance Schema data_locks and data_lock_waits tables, which supersede the INFORMATION_SCHEMA INNODB_LOCKS and INNODB_LOCK_WAITS tables in MySQL ...
https://dev.mysql.com/ndb-transid-mysql-connection-map-table.html
The ndb_transid_mysql_connection_map table provides a mapping between NDB transactions, NDB transaction coordinators, and MySQL Servers attached to an NDB Cluster as API nodes. This information is used when populating the server_operations and ...
https://dev.mysql.com/threads-table.html
row *************************** THREAD_ID: 1 NAME: thread/sql/main TYPE: BACKGROUND PROCESSLIST_ID: NULL PROCESSLIST_USER: NULL PROCESSLIST_HOST: NULL PROCESSLIST_DB: NULL PROCESSLIST_COMMAND: NULL PROCESSLIST_TIME: 80284 PROCESSLIST_STATE: NULL ...
https://dev.mysql.com/encryption-functions.html
If AES_DECRYPT() detects invalid data or incorrect padding, it returns NULL. However, it is possible for AES_DECRYPT() to return a non-NULL value (possibly garbage) if the input data or the key is invalid. The value is returned as a string of 32 ...
https://dev.mysql.com/information-functions.html
The result value is 0, or NULL for inappropriate arguments such as a NULL or negative repeat count. mysql> SELECT DATABASE(); -> 'test' If there is no default database, DATABASE() returns NULL. The value of LAST_INSERT_ID() is not changed if you set ...It may be used to time how quickly MySQL processes the ...
https://dev.mysql.com/load-xml.html
Suppose that we have a table named person, created as shown here: USE test; CREATE TABLE person ( person_id INT NOT NULL PRIMARY KEY, fname VARCHAR(40) NULL, lname VARCHAR(40) NULL, created TIMESTAMP ); Suppose further that this table is initially ...The tagname in the optional ROWS IDENTIFIED BY clause must also be given as a literal string, and must be surrounded by angle brackets (< and ...
https://dev.mysql.com/mathematical-functions.html
Returns NULL if X is not in the range -1 to 1. mysql> SELECT ACOS(1); -> 0 mysql> SELECT ACOS(1.0001); -> NULL mysql> SELECT ACOS(0); -> 1.5707963267949 ASIN(X) Returns the arc sine of X, that is, the value whose sine is X. Returns NULL if X is not ...mysql> SELECT ABS(2); -> 2 mysql> SELECT ABS(-32); -> 32 This function is safe to use with BIGINT ...
https://dev.mysql.com/example-foreign-keys.html
In MySQL, InnoDB tables support checking of foreign key constraints. See Chapter 15, The InnoDB Storage Engine, and Section 1.8.2.3, “Foreign Key Differences”. A foreign key constraint is not required merely to join two tables. It is extremely ...
Document created the 26/06/2006, last modified the 26/10/2018
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