What is the importance of understanding the SQL language? For every student who jumps into the world of IT, SQL language is one of the most important things to learn and the fundamentals of database systems. SQL is a Structured Query Language which is a special language used to create and process databases.
Every IT practitioner will always meet with SQL when they learn to process databases. Without SQL, there is no database and from this fact, we can understand the importance of SQL in the IT world. We will also talk about what to prepare before facing SQL interview questions.
Structured Query Language or commonly called SQL is a special language that is used to access data that is in a relational database. SQL is a computer language that uses the standard ANSI (American National Standard Institute) that is used in relational database management. With SQL or can also be called a query, we can manipulate or edit the database as we want like running queries to retrieve data, add data, update data and delete data. The language is important in dealing with fundamentals of database systems.
Until now almost all database servers and other database software know and are able to interpret the SQL language. Therefore learning SQL language is very important for those who are struggling in the IT field and who are always in contact with relational databases. In fact, SQL developer jobs are wanted by many IT students.
Types of SQL commands:
In SQL implementation there are various commands that are used to access and manage data contained in the database. These commands can be grouped into three sub-commands.
The three sub commands are:
– DDL (Data Definition Language)
– DML (Data Manipulation Language)
– DCL (Data Control Language)
Next what is meant by DDL, DML, and DCL??? For your info, their definition is one of the important ones among common SQL interview questions.
Here is an explanation of the question mark:
DDL (Data Definition Language)
DDL is a basic command of the SQL language that is intended to create a database structure in both database creation and tables.
DML (Data Manipulation Language)
DML is a command of the SQL language used to manipulate data in the database.
DCL (Data Control Language)
DCL is a SQL command that is used to set user access rights, both to the database and to tables and fields that exist. That way the database admin can maintain the confidentiality of a database.
SQL (Structured Query Language) like at a glance that has been explained in the SQL definition above, has several functions as follows:
– SQL allows us to access and change databases.
– SQL can run queries against the database.
– SQL can retrieve data from the database.
– SQL can insert data into the database.
– SQL can update data into the database.
– SQL can delete data in the database.
– SQL can create a new procedure that will be stored in the database.
– SQL can set access rights in tables, procedures, and other things.
If you are an IT practitioner who will apply for SQl jobs as above, preparing yourself for SQL interview questions is very important. The following are tips that I got from my experience while undergoing the interview a few years ago. But if you have no experience, just click here and you’ll get a clear picture about SQL interview questions.
Just like other tests, SQL test depends on how well you understand the SQL functions above.
Knowing the topics to be asked is the second step. Understanding the following topics will increase your chances of success in facing SQL interview questions.
Database Relationships: These are what refer to data sets, which are arranged by tables, columns and records.
Data Type: There are various types of data that you must know; Date Time, Boolean, and Character and so on.
Display: This refers to how SQL is displayed. SQL is displayed as a virtual table containing a collection of data. The table is stored in the database in the form of a SELECT Question.
Join: This refers to merging different types of SQL.
Main and Foreign Keys: These two keys represent two different functions. The Primary Key has a function to identify records in a table. The Foreign Key connects two different tables simultaneously
Trigger: This is a kind of procedure in any SQL developer job that sets a set of statements that are stored securely in the database. If you want to check the integrity of your data, dealing with Trigger is a must.
There are still several other functions that might be asked, but the functions above are mandatory for you to know. Finally, in any interview, including SQL test and interviews