Para cada base definir 4 usuarios particulares

1. solo lectura local ( para logins y consultas SELECT )
2. read-write no delete local
3. only delete local
4. full remoto - nombre bien ofuscado

For each application running on the server, only give access to a user who is in charge of a database for a given application. For example, if you have a wordpress site, create a specific user for the wordpress site database as follows.

mysql -u root -p
> CREATE DATABASE osclass_db;
> CREATE USER 'osclassdmin'@'localhost' IDENTIFIED BY 'osclass@dmin%!2';
> GRANT ALL PRIVILEGES ON osclass_db.* TO 'osclassdmin'@'localhost';
> FLUSH PRIVILEGES;
> exit

and remember to always remove user accounts that are no longer managing any application database on the server.

Ejemplo para privilegios remotos en la subred 186.182.3.1 - 186.182.3.254

GRANT ALL PRIVILEGES ON osclass_db.* TO 'remoteosclassdmin'@'186.182.3.%' IDENTIFIED BY 'PASSWORD' WITH GRANT OPTION;

https://www.upguard.com/articles/top-11-ways-to-improve-mysql-security

Use datatypes based on the nature of data. If you use irrelevant datatypes it may consume more space or may lead to errors. Example: Using varchar (20) to store date time values instead of DATETIME datatype will lead to errors during date time-related calculations and there is also a possible case of storing invalid data.

If you string a single character, use CHAR(1) instead of VARCHAR(1) because VARCHAR(1) will take extra byte to store information

Example: Using char(1000) instead of varchar(1000) will consume more space if the length of data is less than 1000

When you use DATETIME or DATE datatype always use YYYY-MM-DD date format or ISO date format that suits your SQL Engine. Other regional formats like DD-MM-YYY, MM-DD-YYYY will not be stored properly.

Make sure to index the columns which are used in JOIN clauses so that the query returns the result fast. If you use UPDATE statement that involves more than one table make sure that all the columns which are used to join the tables are indexed

Using functions over indexed columns defeats the purpose of the index. Suppose you want to get data where first two character of customer code is AK, do not write

SELECT columns FROM table WHERE left (customer_code,2)=’AK’

but rewrite it using

SELECT columns FROM table WHERE customer_code like ‘AK%’

which will make use of index which results in faster response time.

Do not just blindly use SELECT * in the code. If there are many columns in the table, all will get returned which will slow down the response time particularly if you send the result to a front-end application. Explicitly type out the column names which are actually needed.

If you want to show the result in front-end application, let it ORDER the result set. Doing this in SQL may slow down the response time in the multi-user environment.

If you develop an application that reads data more often than writing (ex: search engine), choose MyISAM storage engine. If you develop an application that writes data more often than reading (ex: real-time bank transactions), choose INNODB storage engine. Choosing wrong storage engine will affect the performance

If you want to check the existence of data, do not use

If (SELECT count(*) from Table WHERE col=’some value’)>0

instead, use EXISTS clause

If EXISTS(SELECT * from Table WHERE col=’some value’)

which is faster in response time.