SQL "for dummies": what do beginners need to know?

Today, dummy SQL courses are becoming increasingly popular. This can be very simply explained, because in the modern world you can increasingly find the so-called β€œdynamic” web services. They differ in a rather flexible shell and are based on databases. All novice programmers who decide to devote themselves to creating sites are primarily enrolled in SQL courses "for dummies."

SQL for Dummies

Why learn this language?

First of all, SQL is taught in order to further develop a wide variety of applications for one of the most popular blog engines today - WordPress. After passing a few simple lessons, you can already create queries of any complexity, which only confirms the simplicity of this language.

What is SQL?

The Structured Query Language, or structured query language, was created with one single purpose: to determine the type of data, provide access to it and process it for fairly short periods of time. If you know the SQL value, then it will be clear to you that this server belongs to the so-called "non-procedural" languages. That is, its capabilities include only a description of any components or results that you want to see in the future on the site. But at the same time, the programmer does not indicate exactly what the results are going to get. Each new request in this language is like an additional "add-on". It is in the order in which they are entered into the database that the queries will be executed.

SQL Server for Dummies

What procedures can be performed using this language?

Despite its simplicity, the SQL database allows you to create quite a lot of the most diverse queries. So what can you do if you learn this important programming language?

  • create a wide variety of tables;
  • Receive, store and modify received data;
  • Change the structure of tables at your discretion;
  • Combine the received information into single blocks;
  • calculate the received data;
  • provide full protection of information.

SQL value

Which teams are the most popular in a given language?

If you decide to attend SQL courses "for dummies", then you will receive detailed information about the commands that are used in creating queries using it. The most common today are:

  1. DDL - is a command that defines data. It is used to create, modify and delete a wide variety of objects in the database.
  2. DCL - is a team that manages data. It is used to provide different users access to information in the database, as well as to use tables or views.
  3. TCL is a team that manages a wide variety of transactions. Its main purpose is to determine the progress of the transaction.
  4. DML - manipulates the received data. Its task is to allow the user to move various information from the database or enter it there.

Types of privileges that exist on this server

Privileges are understood as those actions which this or that user can carry out according to his status. The most minimal, of course, is a regular login. Of course, privileges can change over time. Old ones will be deleted, and new ones will be added. Today, all those who take SQL Server "Dummies" courses know that there are several types of actions allowed:

  1. Object type - the user is allowed to execute any command only with respect to a specific object that is in the database. At the same time, privileges are different for different objects. They are also tied not only to a particular user, but also to tables. If someone, using his capabilities, created a table, then he is considered its owner. Therefore, in his right to assign new privileges to other users associated with the information in it.
  2. The system type is the so-called data copyright. Users who have received such privileges can create various objects in the database.

SQL database

SQL History

This language was created by an IBM research lab in 1970. At that time, its name was somewhat different (SEQUEL), but after several years of use it was changed, slightly reduced. Despite this, even today many well-known world experts in the field of programming still pronounce the name in the old fashioned way. SQL was created for the sole purpose of inventing a language that was so simple that even simple Internet users could learn it without any problems. An interesting fact is that at that time SQL was not the only such language. In California, another group of specialists developed a similar Ingres, but it never became widespread. Until 1980, there were several variations of SQL that only slightly differed from each other. To prevent confusion, in 1983 its standard version was created, which is still popular today. SQL Dummies courses let you learn a lot more about the service and fully explore it in a few weeks.

Source: https://habr.com/ru/post/A11752/

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