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https://dev.mysql.com/doc/refman/8.4/en/charset-examples.html
Example 1: Table and Column Definition CREATE TABLE t1 ( c1 CHAR(10) CHARACTER SET latin1 COLLATE latin1_german1_ci ) DEFAULT CHARACTER SET latin2 COLLATE latin2_bin; Here we have a column with a latin1 character set and a latin1_german1_ci ... The ...
https://dev.mysql.com/doc/refman/8.4/en/correlated-subqueries.html
A correlated subquery is a subquery that contains a reference to a table that also appears in the outer query. For example: SELECT * FROM t1 WHERE column1 = ANY (SELECT column1 FROM t2 WHERE t2.column2 = t1.column2); Notice that the subquery ...So, ...
https://dev.mysql.com/doc/refman/8.4/en/creating-spatial-indexes.html
For InnoDB and MyISAM tables, MySQL can create spatial indexes using syntax similar to that for creating regular indexes, but using the SPATIAL keyword. To drop spatial indexes, use ALTER TABLE or DROP INDEX: With ALTER TABLE: ALTER TABLE geom DROP ...For storage engines that support nonspatial indexing of spatial columns, the engine creates a B-tree ...
https://dev.mysql.com/doc/refman/8.4/en/faqs-stored-procs.html
You can obtain information about existing stored procedures using the ROUTINES table in the INFORMATION_SCHEMA database (see Section 28.3.30, “The INFORMATION_SCHEMA ROUTINES Table”). For a database named dbname, use this query on the ...Where ...
https://dev.mysql.com/doc/refman/8.4/en/handler-scope.html
However, SQLSTATE handlers take precedence over SQLEXCEPTION handlers, so if the table t is nonexistent, the DROP TABLE statement raises a condition that activates the SQLSTATE handler: mysql> CALL p1(); +--------------------------------+ | msg | ...
https://dev.mysql.com/doc/refman/8.4/en/innodb-and-mysql-replication.html
For example, you can replicate modifications to an InnoDB table on the source to a MyISAM table on the replica. Cascading actions for InnoDB tables on the source are executed on the replica only if the tables sharing the foreign key relation use ...
https://dev.mysql.com/doc/refman/8.4/en/innodb-online-ddl.html
The online DDL feature provides support for instant and in-place table alterations and concurrent DML. Benefits of this feature include: Improved responsiveness and availability in busy production environments, where making a table unavailable for ...For in-place operations, the ability to adjust the balance between performance and concurrency during DDL operations using the LOCK ...
https://dev.mysql.com/doc/refman/8.4/en/kill.html
Thread processlist identifiers can be determined from the ID column of the INFORMATION_SCHEMA PROCESSLIST table, the Id column of SHOW PROCESSLIST output, and the PROCESSLIST_ID column of the Performance Schema threads table. ALTER TABLE operations ... KILL [CONNECTION | QUERY] processlist_id Each connection to mysqld runs in a separate ...
https://dev.mysql.com/doc/refman/8.4/en/mysqldump-delimited-text.html
If you invoke mysqldump with the --tab=dir_name option, it uses dir_name as the output directory and dumps tables individually in that directory using two files for each table. For a table named t1, the files are named t1.sql and t1.txt. The .sql ...
https://dev.mysql.com/doc/refman/8.4/en/outer-join-optimization.html
MySQL implements an A LEFT JOIN B join_specification as follows: Table B is set to depend on table A and all tables on which A depends. Table A is set to depend on all tables (except B) that are used in the LEFT JOIN condition. The LEFT JOIN ...If ...