SQL: Prefix Indexes Explained

In this sql tutorial video we'll walk you through prefix indexes in database management systems.

A sql index is a database structure allowing for quicker searches. Do note that a sql index also slows down INSERT and UPDATE queries at the same time.

Prefix indexes are very useful when we work with lengthy columns where adding a SQL index on the whole column would consume a lot of disk space. Prefix SQL indexes can be added by either adding one when your table is created or by altering its structure afterwards. Here's how to create a prefix SQL index once a table is created (here we add a sql index for the first 10 characters in a column named "column"):

CREATE TABLE `demo_table` (
`column` VARCHAR(125) NOT NULL DEFAULT 'None',
...
INDEX(column(10))
);

To choose a proper prefix index in a DBMS, choose a SQL index that is long enough to give selectivity, but also short enough to give space.
Subscribe to learn more about databases and indexes within them, and until next time.

Some of the most popular SQL interview questions and answers can be found below:

Q: MySQL password not working. What do I do?

Q: MySQL MyISAM vs InnoDB. Which one to use?
A: Use InnoDB unless you intend to run COUNT(*) queries because MyISAM stores the row count inside of itself.

A: The file is applicable to a Windows OS.

A: The location of the file can vary, but some of the most common locations include:

Q: What are some of the most popular SQL commands?
A: CRUD queries are the most popular SQL queries. They can be used to create (insert), read (select), update, or delete data.

Q: How dangerous is SQL injection? How to protect our web applications from this attack?
A: SQL injection is one of the most dangerous attacks targeting applications today. To protect our web applications from sql injection, we need to sanitize our inputs and never provide user input to a database.

Q: What file should be used for mysql server configuration?

Q: MySQL vs PostgreSQL. What are the main differences?
A: The main difference is that PostgreSQL is an object-relational DBMS while MySQL is a relational DBMS.

Q: What storage engine should we use in our MySQL install?
A: Use either InnoDB or Percona XtraDB. If there's a necessity to run COUNT(*) queries, use MyISAM, because InnoDB and Percona XtraDB don't store the row count internally while MyISAM does.

Q: What is the most frequently used type of SQL index?
A: A B-tree SQL index is used the most frequently in mysql server as well as other RDBMS systems.

Enjoy the video!

#shorts #reels #database #mysql #web #developer #dev