14.1 Advanced Select Queries
In this section, we will delve deeper into the SELECT statement, which is an essential tool for retrieving data from a database. As you may already know, the SELECT statement is used to select data from one or more tables in a database. It can retrieve individual columns, specific rows or even entire tables of data.
When using the SELECT statement, it is important to understand the syntax and structure of the statement. This includes the use of keywords such as FROM, WHERE, GROUP BY, HAVING, and ORDER BY. These keywords allow you to filter, sort, and group the data returned by the statement.
Another important aspect of the SELECT statement is the use of functions. These functions can be used to manipulate the data returned by the statement. Common functions include COUNT(), SUM(), AVG(), MAX(), and MIN(). These functions can be used to perform calculations on the data or to aggregate the data in some way.
In addition to using the SELECT statement to retrieve...