Structured Query Language (SQL)
The Structured Query Language (SQL) forms the backbone of most modern database systems. These links provide the best resources on the Net for neophytes and expert database administrators alike!
Combining Query Results with the UNION Command
SQL’s UNION command allows you to combine the results of two or more database queries that are not necessarily linked through a database relationship. For example, imagine that you have a school database and wish to use it to create a master contact list for all students, faculty and staff. Looking at your database, you discover that the records corresponding to each of these constituencies appears in separate database tables.
SQL’s UNION command allows you to combine the results of two or more database queries that are not necessarily linked through a database relationship. For example, imagine that you have a school database and wish to use it to create a master contact list for all students, faculty and staff. Looking at your database, you discover that the records corresponding to each of these constituencies appears in separate database tables.
Free Learning SQL E-Course
The Structured Query Language (SQL) forms the backbone of all relational databases. This language offers a flexible interface for databases of all shapes and sizes and is used as the basis for all user and administrator interactions with the database. In this course, you'll learn the basics of using SQL to store, retrieve and manipulate information in a database.
The Structured Query Language (SQL) forms the backbone of all relational databases. This language offers a flexible interface for databases of all shapes and sizes and is used as the basis for all user and administrator interactions with the database. In this course, you'll learn the basics of using SQL to store, retrieve and manipulate information in a database.
Structured Query Language Frequently Asked Questions
Looking for advice on using the Structured Query Language? The About Databases SQL FAQ provides answers to the most frequently asked questions about SQL and databases.
Looking for advice on using the Structured Query Language? The About Databases SQL FAQ provides answers to the most frequently asked questions about SQL and databases.
Controlling Data Access with Views
Database views allow you to easily reduce the complexity of the end user experience and limit their ability to access data contained in database tables by limiting the data presented to the end user. Essentially, a view uses the results of a database query to dynamically populate the contents of an artificial database table.
Database views allow you to easily reduce the complexity of the end user experience and limit their ability to access data contained in database tables by limiting the data presented to the end user. Essentially, a view uses the results of a database query to dynamically populate the contents of an artificial database table.
Classifying Results with SQL CASE Statements
SQL includes a CASE statement that allows you to return varying results based upon the evaluation of expressions. You can use a CASE statement anywhere within a SQL statement that you would normally include an expression. CASE statements are often found in SELECT, UPDATE and DELETE statements as well as WHERE and IN clauses.
SQL includes a CASE statement that allows you to return varying results based upon the evaluation of expressions. You can use a CASE statement anywhere within a SQL statement that you would normally include an expression. CASE statements are often found in SELECT, UPDATE and DELETE statements as well as WHERE and IN clauses.
Inserting Data with the SQL INSERT Command
The INSERT command in SQL is used to add records to an existing table. Returning to the personal_info example from the previous section, let's imagine that our HR department needs to add a new employee to their database.
The INSERT command in SQL is used to add records to an existing table. Returning to the personal_info example from the previous section, let's imagine that our HR department needs to add a new employee to their database.
Deleting Database Tables with the DROP Command
The DROP command allows us to remove entire database objects from our database.
The DROP command allows us to remove entire database objects from our database.
Using the GROUP BY Clause to Group SQL Query Results
You may use basic SQL queries to retrieve data from a database but this often doesn’t provide enough intelligence to meet business requirements. SQL also provides you with the ability to group query results based upon row-level attributes in order to apply aggregate functions using the GROUP BY clause.
You may use basic SQL queries to retrieve data from a database but this often doesn’t provide enough intelligence to meet business requirements. SQL also provides you with the ability to group query results based upon row-level attributes in order to apply aggregate functions using the GROUP BY clause.
Self Joins
Looking for a definition of self-join? Find it in the About Databases Glossary!
Looking for a definition of self-join? Find it in the About Databases Glossary!
Concatenation
Interested in the definition of concatenation? Find out in the About Databases glossary!
Interested in the definition of concatenation? Find out in the About Databases glossary!
Joining Multiple Tables with SQL Inner Join Statements
You can use SQL JOIN statements to combine data from three or more tables. In an earlier article, we took a look at using inner joins and outer joins to combine data from two different tables. In many cases, youll want to take this a step further and combine data from three or more tables. Let's take a look at the SQL statements that allow you to accomplish this goal for an inner join.
You can use SQL JOIN statements to combine data from three or more tables. In an earlier article, we took a look at using inner joins and outer joins to combine data from two different tables. In many cases, youll want to take this a step further and combine data from three or more tables. Let's take a look at the SQL statements that allow you to accomplish this goal for an inner join.
Self-Joins in SQL
You can use a self-join to simplify nested SQL queries where the inner and outer queries reference the same table. These joins allow you to retrieve related records from the same table.
You can use a self-join to simplify nested SQL queries where the inner and outer queries reference the same table. These joins allow you to retrieve related records from the same table.
Structured Query Language (SQL)
Most large-scale databases use the Structured Query Language (SQL) to define all user and administrator interactions. This language offers a flexible interface for databases of all shapes and sizes.
Most large-scale databases use the Structured Query Language (SQL) to define all user and administrator interactions. This language offers a flexible interface for databases of all shapes and sizes.
Book Review: SQL Cookbook
O'Reilly's SQL Cookbook is the best reference I've seen for skilled SQL developers. Modeled after a true cookbook, it offers many short snippets of SQL code designed to solve specific problems. You can pick and choose the ingredients you need to help complete your SQL project.
O'Reilly's SQL Cookbook is the best reference I've seen for skilled SQL developers. Modeled after a true cookbook, it offers many short snippets of SQL code designed to solve specific problems. You can pick and choose the ingredients you need to help complete your SQL project.
Retrieving Data with the SELECT Statement
The SELECT command is the most commonly used command in SQL. It allows database users to retrieve the specific information they desire from an operational database.
The SELECT command is the most commonly used command in SQL. It allows database users to retrieve the specific information they desire from an operational database.
Introduction to SQL
The Structured Query Language (SQL) is the language of databases. All modern relational databases, including Access, FileMaker Pro, Microsoft SQL Server and Oracle use SQL as their basic building block. In fact, it’s often the only way that you can truly interact with the database itself.
The Structured Query Language (SQL) is the language of databases. All modern relational databases, including Access, FileMaker Pro, Microsoft SQL Server and Oracle use SQL as their basic building block. In fact, it’s often the only way that you can truly interact with the database itself.
Using Self-Joins in SQL
Did you know that you can use a self-join to simplify nested SQL queries where the inner and outer queries reference the same table? Let's take a look at an example.
Did you know that you can use a self-join to simplify nested SQL queries where the inner and outer queries reference the same table? Let's take a look at an example.
SQL Visual Quickstart
This software-independent book takes a hands-on approach to learning SQL. After some brief introductory material, it dives right into developing SQL queries designed to meet specific goals. It's a great reference for those who occasionally use SQL and forget the details.
This software-independent book takes a hands-on approach to learning SQL. After some brief introductory material, it dives right into developing SQL queries designed to meet specific goals. It's a great reference for those who occasionally use SQL and forget the details.
Creating Databases and Tables In SQL
Learn to create databases and tables using the Structured Query Language (SQL) in this step-by-step tutorial from your About.com Guide to Databases.
Learn to create databases and tables using the Structured Query Language (SQL) in this step-by-step tutorial from your About.com Guide to Databases.
SQL Fundamentals
Would you like to learn SQL? This tutorial will introduce you to the basics.
Would you like to learn SQL? This tutorial will introduce you to the basics.
Access Controls in SQL
Our databases contain information that is vital to the continued operations of our organizations. In this article, your About.com Guide introduces the SQL commands used to control access to your database.
Our databases contain information that is vital to the continued operations of our organizations. In this article, your About.com Guide introduces the SQL commands used to control access to your database.
Aggregate Functions in SQL
SQL provides several aggregate functions to assist with data summarization. In this article we explore the usage of SUM, AVG, COUNT, MIN and MAX.
SQL provides several aggregate functions to assist with data summarization. In this article we explore the usage of SUM, AVG, COUNT, MIN and MAX.
All About NULL Values
Users new to the world of databases are often confused by a special value particular to our field � the NULL value. Read about the proper uses of NULL in this article.
Users new to the world of databases are often confused by a special value particular to our field � the NULL value. Read about the proper uses of NULL in this article.
Creating Databases and Tables in SQL
Just getting started with the Structured Query Language? This tutorial walks you through the process of creating tables and databases in SQL databases.
Just getting started with the Structured Query Language? This tutorial walks you through the process of creating tables and databases in SQL databases.
Deleting Data from SQL Tables
The SQL DELETE command allows the removal of some or all of the data stored in a relational database table.
The SQL DELETE command allows the removal of some or all of the data stored in a relational database table.
Retrieving Data from Multiple Tables with SQL Joins
SQL join statements allow you to combine data from two or more tables in your query results. Learn how to leverage this powerful technology to supercharge your database queries.
SQL join statements allow you to combine data from two or more tables in your query results. Learn how to leverage this powerful technology to supercharge your database queries.
Retrieving Data with SQL Queries
Learn to retrieve information from your database with the SQL SELECT statement. This tutorial provides an introduction to the basics of database queries.
Learn to retrieve information from your database with the SQL SELECT statement. This tutorial provides an introduction to the basics of database queries.
SQL Fundamentals
The Structured Query Language provides the foundation for all relational database systems. Join us as we explore the fundamental concepts behind this powerful language.
The Structured Query Language provides the foundation for all relational database systems. Join us as we explore the fundamental concepts behind this powerful language.
Summarizing Data with CUBE and ROLLUP
SQL's CUBE and ROLLUP commands allow for the efficient summarization of data.
SQL's CUBE and ROLLUP commands allow for the efficient summarization of data.
Fuzzy Logic and SQL
How can fuzzy logic be used to enhance SQL? Fuzzy Systems Solutions markets a tool that does just that! This series explains the basics.
How can fuzzy logic be used to enhance SQL? Fuzzy Systems Solutions markets a tool that does just that! This series explains the basics.
Getting Started with SQL
The Web Developer's Virtual Library provides a very readable introduction to the Structured Query Language.
The Web Developer's Virtual Library provides a very readable introduction to the Structured Query Language.
SQL for Web Nerds
A tremendous resource for all database administrators! Philip Greenspun provides the complete text of an SQL reference book online.
A tremendous resource for all database administrators! Philip Greenspun provides the complete text of an SQL reference book online.
SQL Optimization
Are your SQL queries as efficient as possible? BASIS Corporation provides a feature article describing SQL optimization techniques.
Are your SQL queries as efficient as possible? BASIS Corporation provides a feature article describing SQL optimization techniques.
Teach Yourself SQL in 21 Days
This online book from Que offers a three-week tutorial on the Structured Query Language. At the conclusion of the series of lessons, readers will have gained a solid understanding of SQL concepts.
This online book from Que offers a three-week tutorial on the Structured Query Language. At the conclusion of the series of lessons, readers will have gained a solid understanding of SQL concepts.