In this tutorial, we will learn about the MySQL UNION operator. Suppose you encounter a situation in which you need to combine the results of two different queries. What would you do in such a case? MySQL provides us with the UNION operator for this purpose. MySQL UNION is used to combine the result-set of …
MySQL UNION – Show Combined Data From Multiple MySQL Tables Read More »
In this tutorial, we will learn about MySQL Alias. Suppose you have a query in which you are displaying the Department column and the COUNT(*) column which returns the number of employees in each department. To us programmers, we can understand what COUNT(*) means but when you present your results to someone who doesn’t understand …
MySQL Alias – An Easy Way to Setup Aliases in MySQL Read More »
In this tutorial, we will learn about the MySQL HAVING Clause. The MySQL HAVING clause is used along with the GROUP BY clause. The HAVING Clause adds a condition to the groups and returns only those groups for whom the condition evaluates to true. In short, it restricts the rows returned by the GROUP BY …
In this tutorial, we will learn about the following MySQL aggregate functions – COUNT(), SUM() and AVG(). Suppose we want to count the number of employees from a table who are in the Marketing department. Or what if we wanted to find the average salary of employees in a company? How about situations in which …
MySQL Aggregate Functions – COUNT(), SUM() and AVG() Read More »
In this tutorial, we will learn about MySQL ANY and ALL operators. ANY and ALL operators are logical operators. They are usually used with the WHERE and HAVING clauses. The ANY operator returns true if any of the subquery values satisfy the given condition. The ANY operator compares a value to each value in the …
In this tutorial, we will learn about the MIN() and MAX() aggregate functions. Suppose you want to find the highest-paid employee in your company. Won’t it be very easy if there was a function which you could use directly to get the result? MySQL MAX() does exactly that for you. The MIN() function does the …
In this tutorial, we will learn about how to write MySQL subqueries. A subquery is a query nested within another query. For instance, a subquery can be having a SELECT statement inside another SELECT statement. Multiple MySQL subqueries can be nested within a query. The subquery is called an Inner query and the main query …
In this tutorial, we will learn about the DROP and TRUNCATE statements in MySQL. Suppose we want to delete a table from the database altogether. Or, what if, we want to keep the table but delete all the records in the table? These are common operations in MySQL and for that, we use the DROP …
The MySQL ALTER command is used to modify an existing table. It forms a part of the Data Definition Language (DDL) in SQL, which deals with the definition of data. Other commands in DDL are – CREATE, RENAME, and DROP. When you go buy pieces of clothing, I’m sure you must have come across a …
In this tutorial, we will learn about the MySQL DELETE query. Suppose you are a school teacher and you maintain a table of records of all the students in your class. Now, in the middle of the year, a student transfers to a different school. Keeping that student’s record would be a waste as it …