Php+mysql Query Optimization Simple instance _php tutorial

Php+mysql Query Optimization Simple instance

This article mainly introduces the simple example of Php+mysql query optimization, analyzes the techniques of SQL statement optimization query in Php+mysql program design, and has some reference value for improving the query efficiency, the friends who need can refer to

In this paper, the method of Php+mysql query optimization is analyzed. Share to everyone for your reference. The specific analysis is as follows:

Php+mysql is one of the most frequently used gold partners, both of which are used to perform the best performance and, of course, even more perfect if used with Apache.

Therefore, you need to do a good job of MySQL query optimization, following a simple example, to show the impact of different SQL statements on query speed.

There is a table test that has a self-increment ID as the primary index, and now you want to query the record with the ID number in a range, you can use the following SQL statement:

The code is as follows:

SELECT *
From ' Test '
ORDER BY ID ASC
Limit 208888,50

This SQL statement means that the record from the ID number 208888 starts to fetch 50 records, test in a database of 300,000 records, when the primary index has been established, the time to execute this statement is 40-50 seconds, then there is no faster SQL statement to execute it? Obviously, look at the following SQL statement:

The code is as follows:

SELECT *
From ' Test '
WHERE ID
Between 208838
and 208888

This statement uses a condition to filter, and the actual test execution time is approximately 0.06 seconds.

The reason is because although the id attribute is already indexed, but the order is still a very expensive operation, to use caution, and the second statement, you can let MySQL make full use of the database has been established B + Tree index, so the search speed is very fast, is hundreds of times times the original.

This shows that the site developers in the use of SQL statements, must be cautious, because a careless SQL statement, may make your website access speed down sharply, the background database is under great pressure, and quickly into the predicament of unable to open the page.

It is hoped that this article is helpful to everyone's php+mysql program design.

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