Top 6 Free Courses to learn PHP and MySQL in 2025 [Updated] - Best of lot

If you want to build web applications quickly like overnight or over the weekend, then PHP and MySQL are the right choices and because of this power, they are also the best language for freelancing and startups where a quick turnaround time is required. PHP and MySQL are incredibly powerful open source technologies that allow programmers and web developers to create functional websites and apps that go way beyond basic HTML. PHP is specially designed to generate interactive and dynamic websites and is also known as the server-side scripting language, while MySQL is one of the leading relational databases along with Oracle and Microsoft SQL Server.

Second Highest Salary in MySQL and SQL Server - LeetCode Solution

Write a SQL query to get the second highest salary from the Employee table.

+----+--------+
| Id | Salary |
+----+--------+
| 1  | 100    |
| 2  | 200    |
| 3  | 300    |
+----+--------+

For example, given the above Employee table, the second highest salary is 200. If there is no second highest salary, then the query should return NULL. You can write SQL query in any of your favorite databases e.g. MySQL, Microsoft SQL Server, or Oracle. You can also use database specific feature e.g. TOP, LIMIT or ROW_NUMBER to write SQL query, but you must also provide a generic solution which should work on all database. 

Difference between Self and Equi Join in SQL - INNER Join example MySQL

The main difference between Self Join and Equi Join is that In Self Join we join one table to itself rather than joining two tables. Both Self Join and Equi Join are types of INNER Join in SQL, but there is a subtle difference between the two. Any INNER Join with equal as join predicate is known as Equi Join. SQL Joins are the fundamental concept of SQL similar to correlated and noncorrelated subqueries or using group by clause and a good understanding of various types of SQL join is a must for any programmer.