Database Table Maintenance Statements in MySQL

SQL LIKE allows you to perform pattern matching in your characters column in a database table. SQL LIKE is often used with SELECT statement in WHERE clause. MySQL provides you two wildcard characters for use with LIKE, the percentage % and underscore _.

?Percentage (%) wildcard allows you to match any string of zero or more characters
?Underscore (_) allows you to match any sing character.

SQL UNION allows you to combine two or more result sets from select statements into a single result set. The usage of using SQL UNION is as follows:

SELECT statement
UNION [DISTINCT | ALL]
SELECT statement
UNION [DISTINCT | ALL]

In some cases, the information we need is not actually stored in the database but we can retrieve it by computing in some ways from stored data. For example, we have OrderDetails table to store order data, we don't know total of money of all selling products when we look at the table. In order to do so, we can use aggregate functions. By definition, aggregate functions allow us to perform a calculation on a set of records and return a single returned value. Aggregate functions ignore null value when performing calculation except COUNT function. Aggregate functions are often used with GROUP BY clause of SELECT statement. Here are aggregate functions which MySQL supports:

In this tutorial, you will learn how to insert data into database tables by using SQL INSERT statement.

INSERT Statement
INSERT statement allows you to insert one or more rows to the table. In MySQL, the INSERT statement form is listed as follows: