https://dev.mysql.com/problems-with-null.html
In SQL, the NULL value is never true in comparison to any other value, even NULL. The following statement returns no rows, because expr = NULL is never true for any expression: mysql> SELECT * FROM my_table WHERE phone = NULL; To look for NULL ...
https://dev.mysql.com/replication-options.html
server_uuid The MySQL server generates a true UUID in addition to the default or user-supplied server ID set in the server_id system variable. In addition, the slave I/O thread generates a warning if either of the following is true: No master having ... The following sections contain information about mysqld options and server variables that are used in replication and for controlling the binary ...
https://dev.mysql.com/replication-sbr-rbr.html
If the statement changes many rows, row-based replication may write significantly more data to the binary log; this is true even for statements that are rolled back. For most users, the mixed replication format should provide the best combination of ...
https://dev.mysql.com/replication-solutions-backups-read-only.html
Note The instructions in this section place the server to be backed up in a state that is safe for backup methods that get the data from the server, such as mysqldump (see Section 4.5.4, “mysqldump — A Database Backup Program”). You should not ...
https://dev.mysql.com/spatial-relation-functions-mbr.html
The return values 1 and 0 indicate true and false, respectively. If any argument is geometrically invalid, either the result is true or false (it is undefined which), or an error occurs. MySQL provides several MySQL-specific functions that test the ...
https://dev.mysql.com/spatial-relation-functions-object-shapes.html
The return values 1 and 0 indicate true and false, respectively, except for ST_Distance(), which returns distance values. If any geometry argument is geometrically invalid, either the result is true or false (it is undefined which), or an error ...
https://dev.mysql.com/subquery-optimization-with-exists.html
That is, the “pushdown” strategy works as long as both of these conditions are true: outer_expr and inner_expr cannot be NULL. AND trigcond(oe_N=ie_N) ) Each trigcond(X) is a special function that evaluates to the following values: X when the ...
https://dev.mysql.com/sys-ps-setup-show-disabled.html
Displays all currently disabled Performance Schema configuration. in_show_instruments BOOLEAN: Whether to display disabled instruments. This might be a long list. in_show_threads BOOLEAN: Whether to display disabled threads. mysql> CALL ...
https://dev.mysql.com/sys-ps-trace-statement-digest.html
Traces all Performance Schema instrumentation for a specific statement digest. If you find a statement of interest within the Performance Schema events_statements_summary_by_digest table, specify its DIGEST column MD5 value to this procedure and ...
https://dev.mysql.com/account-names.html
MySQL account names consist of a user name and a host name, which enables creation of distinct accounts for users with the same user name who can connect from different hosts. This section describes how to write account names, including special ...
