10 Essential SQL Concepts Every Developer Should Know.

Introduction

Specifically, SQL is a programming language for interacting with relational databases and other programs. It can modify and administer database schemas and store and retrieve data. Reports can be easily formatted for professional presentation using SQL commands. SQL is the backbone of all other database-related languages and programs.

What is SQL

SQL stands for Structured Query Language, which was started in 1977 by IBM. Today the language is used extensively in the IT field, mainly by companies that need to manipulate data in databases. SQL had gained tremendous popularity since the 1980s when it was introduced. It’s also referred to as Relational Database Management System (RDBMS). SQL was initially meant for IBM mainframes and was only intended as a language for data manipulation. Still, it is now used across different platforms and languages like Java, C#, and .Net.

10 SQL Concept That Every Developer Should Know

1. SQL is Relational Database: Different database systems exist, such as Relational, Hierarchical, Document, etc. SQL is a Relational Database. RDBMS is short for Relational Database Management System. RDBMS is the foundation for SQL and all modern database systems like MS SQL Server, IBM DB2, Oracle, MySQL, and Microsoft Access. In simple terms, RDMS is a database storing data as tables, i.e., in rows and columns. The table collects related data entries with many columns and rows.

2. Keys in SQL: A key can be a single field or a group of areas in a table. It is used to get records or rows from a data table based on a condition or a need. Keys also link two or more database tables or views together. Here are some of the SQL keys:

• Primary Key: A primary key is a field in a table that gives each row or record in a database table its unique identifier. Primary keys must contain unique values. A table can only have one primary key comprising a single field or more than one. A composite key is what you call a primary key that is made up of more than one field.
• Foreign Keys: A key that connects two tables is called a “foreign key.” This is also called a referencing key sometimes. The relationship between the two tables matches the Primary Key in one table to a Foreign Key in the other table.
• Unique Key: One or more fields or columns in a table serve as the “unique key” for each record in a database. It is like a primary key but only allows one null value and no duplicates.

3. Views in SQL: The purpose of a VIEW is to display the contents of another table, not to keep any data. As such, VIEWS can be considered equivalent to SQL Queries. Some or all of the rows in a table may be included in a view. A single SQL view can display one or more tables’ worth of data. Views strengthen the database’s protections by limiting user access to the specific data they need. They conceal private information and restrict access to only the parts of the data that the user needs to view and (occasionally) change.

4. SQL Joins: Joins combine data from two or more tables into a single result set. Several types of joins exist, including INNER JOIN, LEFT JOIN, RIGHT JOIN, and FULL OUTER JOIN.

5. Normalization of Database: Normalization refers to organizing tables and columns in a database to remove duplicate data while ensuring that each piece of data is used only once. There are levels of normalization: First Normal Form (1NF), Second Normal Form (2NF), and Third Normal Form (3NF).

6. Transactions in SQL: The transaction is a sequence of SQL statements that must be executed in their entirety or not at all. Marketing allows the database to maintain integrity and consistency even if the application stops working. The SQL language has several commands that can be used to start, commit, roll back and set transaction boundaries.

7. Subqueries in SQL: To retrieve data from a single table, use a subquery. They are employed alongside a view or join. When one SELECT statement returns rows from another SELECT account, it is called a subquery. If a table’s primary key is Customer Id and its foreign key is Order Id, you may use a subquery to retrieve orders based on the customer’s id.

8. Cloning Tables in SQL: There may be times when you just want to make an exact copy of an existing table in order to try something out or execute another task without impacting the original table. The steps listed below can be used to handle this scenario if you are using MySQL.

• Use the SHOW CREATE TABLE command to obtain a CREATE TABLE statement that details the source table’s structure, indexes, and other details.
• Execute the statement after modifying it to replace the table name with the name of the clone table. You will have an exact clone table if you do this.
• You can also add an INSERT INTO or SELECT statement if you want the table contents transferred.

9. SQL Sequences: A group of numbers perpetually increased by one is called a sequence. Sequences can be used with SQL to enforce uniqueness in database tables. When an auto-increment column is used, the value in the series can be retrieved row by row and compared to other records to determine if it matches any others.

10. Temporary Tables in SQL: RDBMS exists and supports temporary tables. The same selection, update and join options available with standard SQL Server tables are also available when utilizing Temporary Tables, which is a terrific feature. The main thing to understand about temporary tables is that they will be erased once the client session ends.

Conclusion

Mastering these concepts will allow you to write effective SQL queries and efficiently manage data in a database for your product engineering efforts. Whether you’re a data analyst, database administrator, or software developer, having a solid understanding of SQL is essential for working with relational databases. As you continue to develop your skills, you may encounter more advanced SQL concepts such as subqueries, window functions, and common table expressions. However, by mastering these ten essential concepts, you’ll be well on your way to becoming a proficient SQL user. Finally, it’s important to note that SQL is a constantly evolving language, so staying up-to-date with the latest developments and best practices is crucial for ensuring your SQL code is efficient and effective.