#MYSQL CREATE VIEW EXAMPLES HOW TO#
#MYSQL CREATE VIEW EXAMPLES INSTALL#
#MYSQL CREATE VIEW EXAMPLES TRIAL#

However, once you decide to let more people access and modify your MySQL database, you need to create users and grant them privileges.

#MYSQL CREATE VIEW EXAMPLES INSTALL#

When you install MySQL Server on your system and create a MySQL database, you run the required commands in the MySQL shell as root or administrative user, meaning that you have the full power to control every aspect of your database. Introductionįirst, let’s figure out why we need users and privileges. Learn the basics of user account management and find hints.

#MYSQL CREATE VIEW EXAMPLES HOW TO#

Add Where conditions that will reduce the View result set.This article provides a complete overview of how to create a new user account in MySQL and grant different types of privileges on a MySQL database.

If you can, use aggregate functions when querying the View rather than in the Create View Statement.

Plan the Views correctly and avoid any queries that will use the Temptable algorithm.

So what happens when users start to join various Views together into new Views ? If they use the Merge algorythmn then not much, but if they use Temptable then you will start to take a hit again with performance as your performance issue begins to cascade. It allows MySQL to automatically select the best of the Merge and Temptable options with a preference to use the Merge option. This is the default option set when the Algorithm hasn't been set in the create statement. This can be a disaster when using large datasets. If you then try to add a few clauses when querying this view you will essentially be running the query twice - once where the temporary table is created and then again when your query is used against it. Without a date clause limiting the results to eg the most recent 2years worth of orders, you will get all orders for all time. This can be absolutely dire for performance if you don't have a where clause that significantly narrows down the result set in the View Query.Ĭonsider an example view that contains Customer Orders and Details. Your query will then be run against this table. With the Temptable option MySQL will run the View Query and store the results in a temporary table. So when using the Merge algorithm, the performance of your View is only as good as the query that creates it. Trying to use any of these will force MySQL to use the below Temptable Algorithm. One thing to be away of is that you cannot use the merge algorithm if you have any of the following in your View Query:ġ.Aggregate functions (SUM(), MIN(), MAX(), COUNT(), and so forth)

It is the result set of a stored query in the database server that can then be queried like a table.Ĭonsider this example query to return actors and films they are in ( using the Sakilla sample Database ).Įnter fullscreen mode Exit fullscreen mode While this sounds great it can be an absolute disaster performance-wise for your database.įirst off what exactly is a Database View ? The common solution across their documentation for both issues is to create Views to simplify tables, hide joins etc. Some of these BI tools also allow users to create their own 'Queries' with the tables, which can be confusing as they wont know the schema. I tend to err on the side of caution and do not want to expose my table structure to these applications.

#MYSQL CREATE VIEW EXAMPLES TRIAL#

Recently I have had the opportunity to trial several third party BI tools which integrate with my database. Other flavours of SQL (eg SQL Server, PostgreSQL, SQLite) may be slightly different, SQL Server in particular has Indexed Views which can improve performance.

Mysql create view examples