In the process of software development, you need to master at least one method of using database.
SQL database is the best choice for many people because of its simple syntax, convenient operation and high efficiency. However, SQL statements will be affected by different database functions, so it needs to be optimized in terms of calculation time and language efficiency, and adjusted according to the actual situation.
The following computer training introduces the optimization method of SQL database for everyone.
First of all, an appropriate index is basically a data structure, which helps to speed up the whole data retrieval process.
A unique index is an index that creates non-overlapping data columns.
The correct index can access the database faster, but too many indexes or no indexes will lead to wrong results.
IT training thinks that without index, the processing speed will become very slow.
Second, only relevant data is indexed to specify the accuracy of the data to be retrieved.
Use commands * and LIMIT instead of SELECT*.
When adjusting the database, you must use the required data set instead of the whole data set, especially when the data source is very large, specifying the required data set can save most of the time.
3. Use or avoid using temporary tables as needed. If the code can be written in a simple way, don't complicate the temporary table.
Of course, if the data has a specific program that requires multiple queries, Beida Jade Bird suggests using a temporary table in this case.
Temporary tables are usually replaced by subqueries.
Fourthly, it is very important to avoid coding loops, because it will slow down the whole sequence.
By using a unique single-line UPDATE or INSERT command, the coding cycle is avoided. Jinan Beida Jade Bird found that the WHERE command can ensure that the stored data is not updated, and it is easy to find the matching and pre-existing data.