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MySQL COUNT()

In SQL, the COUNT() aggregation function is used to count the number of records in a table. Knowing the number

The AVG() aggregation function in the SQL language is used to calculate the average value over a set of non-zero

It may be interesting to insert comments in the SQL queries to better understand them when there are large and

In this tutorial, we are going to see how to comment multiple lines in MySQL. Multi-line comment has the advantage

In SQL language, the OPTIMIZE command reorganizes the physical storage of data and rebuilds the indexes. This command can therefore

In SQL language, the EXPLAIN statement is used just before a SELECT and allows you to display the execution plan

In SQL, CREATE INDEX command is used to create an index. The index is useful to speed up the execution

In SQL language, ANY statement allows to compare a value with the result of a subquery. It is thus possible

In SQL language, ALL statement is used to compare a value in the set of values in a subquery. In

In SQL language, the EXISTS statement is used in a conditional clause to find out whether or not rows are