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https://dev.mysql.com/doc/refman/8.4/en/functions.html
Expressions can be written using values from several sources, such as literal values, column values, NULL, variables, built-in functions and operators, loadable functions, and stored functions (a type of stored object). An expression that contains ... Expressions can be used at several points in SQL statements, such as in the ORDER BY or HAVING clauses of SELECT statements, in the WHERE clause of a SELECT, DELETE, or UPDATE statement, or in SET ...
https://dev.mysql.com/doc/refman/8.4/en/gis-point-property-functions.html
Unless otherwise specified, functions in this section handle their geometry arguments as follows: If any argument is NULL, the return value is NULL. A Point consists of X and Y coordinates, which may be obtained using the ST_X() and ST_Y() ...
https://dev.mysql.com/doc/refman/8.4/en/index-extensions.html
Consider this table definition: CREATE TABLE t1 ( i1 INT NOT NULL DEFAULT 0, i2 INT NOT NULL DEFAULT 0, d DATE DEFAULT NULL, PRIMARY KEY (i1, i2), INDEX k_d (d) ) ENGINE = InnoDB; This table defines the primary key on columns (i1, i2). InnoDB ...
https://dev.mysql.com/doc/refman/8.4/en/information-schema-innodb-buffer-page-table.html
The column is NULL if the server has not yet accessed the table. The INNODB_BUFFER_PAGE table provides information about each page in the InnoDB buffer pool. For related usage information and examples, see Section 17.15.5, “InnoDB ...
https://dev.mysql.com/doc/refman/8.4/en/information-schema-key-column-usage-table.html
This table provides no information about functional key parts because they are expressions and the table provides information only about columns. The KEY_COLUMN_USAGE table has these columns: CONSTRAINT_CATALOG The name of the catalog to which the ...
https://dev.mysql.com/doc/refman/8.4/en/information-schema-optimization.html
row *************************** id: 1 select_type: SIMPLE table: cs partitions: NULL type: const possible_keys: PRIMARY,name key: name key_len: 194 ref: const rows: 1 filtered: 100.00 Extra: Using index *************************** 2. row ...
https://dev.mysql.com/doc/refman/8.4/en/information-schema-parameters-table.html
The PARAMETER_NAME and PARAMETER_MODE values are NULL because the return value has no name and the mode does not apply. The PARAMETERS table provides information about parameters for stored routines (stored procedures and stored functions), and ...
https://dev.mysql.com/doc/refman/8.4/en/json-validation-functions.html
Both functions handle null or invalid input as follows: If at least one of the arguments is NULL, the function returns NULL. As before, you can see this by attempting to insert the value into the geo table, then issuing SHOW WARNINGS afterwards: ...
https://dev.mysql.com/doc/refman/8.4/en/multiple-column-indexes.html
MySQL can create composite indexes (that is, indexes on multiple columns). For certain data types, you can index a prefix of the column (see Section 10.3.5, “Column Indexes”). MySQL can use multiple-column indexes for queries that test all the ...
https://dev.mysql.com/doc/refman/8.4/en/mysql-logging.html
Then use either of the following techniques to prevent it from being created again: Set the MYSQL_HISTFILE environment variable to /dev/null. Create .mysql_history as a symbolic link to /dev/null; this need be done only once: ln -s /dev/null ... The ...