Free Articles and Tutorials: SQL
This page contains a listing of free articles and tutorials.
Here we provide a list of free articles and tutorials of tips and tricks that will make you more effective with SQL.
How to Check Multiple Conditions in SQL
A select statement in SQL may contain one or more conditions (also known as predicates) in the where clause. A condition evaluates to true or false or unknown. The where clause must return a true value for a particular row to be selected.
How to Concatenate Strings in SQL
SQL Server, Oracle, MySQL and PostgreSQL each have their own way of doing string concatenation.
In SQL, you round up to the nearest integer using the
CEILING function, depending on whether you're using SQL Server, Oracle, MySQL or PostgreSQL.
How to Select All Columns in a Row in SQL
You might wish to select all the columns in each row of a table in your SQL select statement. The syntax for accomplishing this task is straightforward because it does not require itemizing each column defined for the table.
When you run a select statement the records, or rows, that are displayed are not guaranteed to be in a specific order. Usually, you will want to sort the records to make the report more meaningful. You will learn how to sort records in this topic.
How to Write Subqueries (Simple and Correlated)
A subquery is select statement contained within an outer select statement. Two types of subqueries are available in SQL: the simple subquery and the correlated subquery. In this topic you will learn how to write each type of subquery.
How Work with White Space and Semicolons in Simple SQL Selects
You must use at least one white space character between each keyword, table or column name in an SQL select. In addition, a semicolon is required as the statement delimiter.