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Mysql transaction1/9/2024 This clause is used after SELECT and preceding tables or subqueries. The number of rows can then be retrieved with SELECT FOUND_ROWS(). While calculating rows in this fashion, LIMIT clause is ignored. It tells MySQL to calculate the number of rows in a result set. It can also be used for views if it accompanies a SELECT statement. It tells MySQL not to store the result in the query cache (A DataBase system component which stores the text of a SELECT statement along with the corresponding result sent to the client ). The value of the query_cache_type system variable is 2 or DEMAND. It tells MySQL to store the result in the query cache (A DataBase system component which stores the text of a SELECT statement along with the corresponding result sent to the client ) if it is cacheable. It can not be used for subqueries or following UNION. If used, MySQL can free the table locks early and takes less time to send the result set to the client where it may take a long time. ![]() ![]() It forces the result to be put into a temporary table. It tells the optimizer (a component of DataBase system which determines to the most efficient way of executing a query) that the result set has many rows, so use disk-based temporary tables if needed, and prefer sorting to use a temporary table with a key on the GROUP BY elements. It tells the optimizer (a component of DataBase system which determines to the most efficient way of executing a query) that the result set is small, so use fast temporary tables to store the resulting table instead of using sorting.Ĭan be used with GROUP BY or DISTINCT. This can not be used to make a query fast and also can be used in the table_references list.Ĭan be used with GROUP BY or DISTINCT. If used with SELECT, associated tables are joined in the order they are arranged in the corresponding FROM clause. If a SELECT statements are part of a UNION, you can not use HIGH_PRIORITY along with. And can be used only if the associated query is very fast as well as done at once. It can be used only with MyISAM, MEMORY, and MERGE storage engines. It runs even if the table on which the query is applied is locked by an update query. If used with SELECT, the associated query obtains higher priority than an update statement. ![]() Indicates the name of the table from where the rows will be retrieved.ĭISTINCT clause is used to retrieve unique rows from a table. SELECT statement is used to fetch rows or records from one or more tables.
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