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https://dev.mysql.com/doc/refman/8.4/en/sys-table-exists.html
Tests whether a given table exists as a regular table, a TEMPORARY table, or a view. If both a temporary and a permanent table exist with the given name, TEMPORARY is returned. Parameters in_db VARCHAR(64): The name of the database in which to ...
https://dev.mysql.com/doc/refman/8.4/en/system-schema.html
It contains tables that store information required by the MySQL server as it runs. A broad categorization is that the mysql schema contains data dictionary tables that store database object metadata, and system tables used for other operational ...
https://dev.mysql.com/doc/refman/8.4/en/table-cache.html
When you execute a mysqladmin status command, you should see something like this: Uptime: 426 Running threads: 1 Questions: 11082 Reloads: 1 Open tables: 12 The Open tables value of 12 can be somewhat puzzling if you have fewer than 12 tables.
https://dev.mysql.com/doc/refman/8.4/en/time.html
MySQL retrieves and displays TIME values in 'hh:mm:ss' format (or 'hhh:mm:ss' format for large hours values). The hours part may be so large because the TIME type can be used not only to represent a time of day (which must be less than 24 hours), ...
https://dev.mysql.com/doc/refman/8.4/en/truncate-table.html
Logically, TRUNCATE TABLE is similar to a DELETE statement that deletes all rows, or a sequence of DROP TABLE and CREATE TABLE statements. To achieve high performance, TRUNCATE TABLE bypasses the DML method of deleting data. Thus, it does not cause ...
https://dev.mysql.com/doc/refman/8.4/en/type-conversion.html
When an operator is used with operands of different types, type conversion occurs to make the operands compatible. For example, MySQL automatically converts strings to numbers as necessary, and vice versa. mysql> SELECT 1+'1'; -> 2 mysql> SELECT ...
https://dev.mysql.com/doc/refman/8.4/en/union.html
query_expression_body UNION [ALL | DISTINCT] query_block [UNION [ALL | DISTINCT] query_expression_body] [...] query_expression_body: See Section 15.2.14, “Set Operations with UNION, INTERSECT, and EXCEPT” UNION combines the result from multiple ...
https://dev.mysql.com/doc/refman/8.4/en/using-stack-trace.html
On some operating systems, the error log contains a stack trace if mysqld dies unexpectedly. You can use this to find out where (and maybe why) mysqld died. To get a stack trace, you must not compile mysqld with the -fomit-frame-pointer option to ...
https://dev.mysql.com/doc/refman/8.4/en/view-restrictions.html
The maximum number of tables that can be referenced in the definition of a view is 61. View processing is not optimized: It is not possible to create an index on a view. Indexes can be used for views processed using the merge algorithm. However, a ...
https://dev.mysql.com/doc/refman/8.4/en/view-syntax.html
The CREATE VIEW statement creates a new view (see Section 15.1.23, “CREATE VIEW Statement”). To alter the definition of a view or drop a view, use ALTER VIEW (see Section 15.1.11, “ALTER VIEW Statement”), or DROP VIEW (see Section 15.1.35, ...