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https://dev.mysql.com/doc/refman/8.0/en/innodb-benefits.html
If you split up related data into different tables, you can set up foreign keys that enforce referential integrity. When you design a database with appropriate primary key columns for each table, operations involving those columns are automatically ... InnoDB tables have the following benefits: If the server unexpectedly exits because of a hardware or software issue, regardless of what was happening in the database at the time, you don't need to do anything special after restarting the ...
https://dev.mysql.com/doc/refman/8.0/en/subquery-optimization-with-exists.html
WHERE subquery_where AND (outer_expr=inner_expr OR inner_expr IS NULL)) The need to evaluate the extra IS NULL condition is why MySQL has the ref_or_null access method: mysql> EXPLAIN SELECT outer_expr IN (SELECT t2.maybe_null_key FROM t2, t3 WHERE ... Certain optimizations are applicable to comparisons that use the IN (or =ANY) operator to test subquery ...
https://dev.mysql.com/doc/refman/8.0/en/declare-handler.html
HANDLER statement had not been present, MySQL would have taken the default action (EXIT) after the second INSERT failed due to the PRIMARY KEY constraint, and SELECT @x would have returned 2. statement handler_action: { CONTINUE | EXIT | UNDO } ...
https://dev.mysql.com/doc/refman/8.0/en/information-schema-introduction.html
Beginning with MySQL 8.0.30, information about generated invisible primary keys is visible by default in all INFORMATION_SCHEMA tables describing table columns, keys, or both, such as the COLUMNS and STATISTICS tables. INFORMATION_SCHEMA provides ...
https://dev.mysql.com/doc/refman/8.0/en/information-schema-table-constraints-table.html
The value can be UNIQUE, PRIMARY KEY, FOREIGN KEY, or (as of MySQL 8.0.16) CHECK. The UNIQUE and PRIMARY KEY information is about the same as what you get from the Key_name column in the output from SHOW INDEX when the Non_unique column is 0. The ...
https://dev.mysql.com/doc/refman/8.0/en/replication-features-row-searches.html
If there are suitable indexes, one index is selected from the candidates, in the following priority order: A primary key. If the algorithm is able to select a primary key or a unique index where every column in the index has a NOT NULL attribute, it ... When a replica using row-based replication format applies an UPDATE or DELETE operation, it must search the relevant table for the matching ...
https://dev.mysql.com/doc/refman/8.0/en/date-and-time-literals.html
Standard SQL and ODBC Date and Time Literals Standard SQL requires temporal literals to be specified using a type keyword and a string. DATE 'str' TIME 'str' TIMESTAMP 'str' MySQL recognizes but, unlike standard SQL, does not require the type ...
https://dev.mysql.com/doc/refman/8.0/en/examples.html
Supposing that each trader has a single fixed price per article, then (article, dealer) is a primary key for the records. Here are examples of how to solve some common problems with MySQL. Some of the examples use the table shop to hold the price ...
https://dev.mysql.com/doc/refman/8.0/en/firewall-reference.html
ID An integer column that is a primary key for the table. ID An integer column that is a primary key for the table. When enabled, the firewall bases operational decisions on the cached data. The firewall database can be the mysql system database or ...
https://dev.mysql.com/doc/refman/8.0/en/fulltext-search-mecab.html
The built-in MySQL full-text parser uses the white space between words as a delimiter to determine where words begin and end, which is a limitation when working with ideographic languages that do not use word delimiters. To address this limitation ...