Sql query ebooks download

This book is a free SQL tuning e-book for developers. It avoids unnecessary details about database internals but highlights the one topic that is most often neglected: proper indexing.

Snodgrass - Morgan Kaufmann , Richard Snodgrass and his colleagues have explored temporal data concepts over the last two decades. How we think of a database depends on what use we want to make of the information that it contains. So far, we have talked about a database in it's broadest sense. This very general definition is not what most people mean when they talk about a database.

In this electronic age, the word database has become synonymous with the term "computerised database". Collins English Dictionary describes a database as "A store of a large amount of information, esp. In keeping with popular trend though, we will be using the word database to refer to a computerised database.

A database computerised database remember by itself, is not much use. The data is stored electronically on the computer's disk in a format which we humans cannot read or understand directly.

What we need is some way of accessing this data and converting it into a form which we do understand. This is the job of the database management system or DBMS for short. A DBMS is essentially a suite of programs that act as the interface between the human operator and the data held in the database. Using the DBMS, it is possible to retrieve useful information, update or delete obsolete information and add new information to the database.

As well as data entry and retrieval, the DBMS plays an important role in maintaining the overall integrity of the data in the database. The simplest example of is ensuring that the values entered into the database conform to the data types that are specified. In the early days of computerised databases, all large database systems conformed to either the network data model or the hierarchical data model.

We will not be discussing the technical details of these models except to say that they are quite complex and not very flexible. One of the main drawbacks of these databases was that in order to retrieve information, the user had to have an idea of where in the database the data was stored. This meant that data processing and information retrieval was a technical job which was beyond the ability of the average office manager.

In those days life was simple. Computer literate executives were rare and DP staff with business sense were even more rare.

This was the state of affairs before the advent of relational databases. The relational data model was introduced in , E. The relational database model represented the database as a collection of tables which related to one another. Unlike network and hierarchical databases, the relational database is quite intuitive to use, with data organised into tables, columns and rows. An example of a relational database table is shown in Figure 1.

We can see just by looking at Figure 1. The table is a list of people's names and telephone numbers. It is similar to how we might go about the task of jotting down the phone numbers of some of our friends, in the back of our diary for example. The relational data model consists of a number of intuitive concepts for storing any type of data in a database, along with a number of functions to manipulate the information.

The relational data model as proposed by Codd provided the basic concepts for a new database management system, the relational database management system RDBMS. Soon after the relational model was defined, a number of relational database languages were developed and used for instructing the RDBMS.

Structured Query Language being one of them. The SQL language is so inextricably tied to relational database theory that it is impossible to discuss it without also discussing the relational data model.

The next two sections briefly describe some of the concepts of this model. We have already seen that a relational database stores data in tables. Search Engine. The authors, experts in tune with common web development tasks, will guide you through several projects that are complete, tested, and ready to be implemented, so that you can understand by doing.

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You'll take an in-depth look at why the combination of PHP, MySQL, and Apache has become so popular: flawless interaction, flexibility, customization, and cost, as well as their ability to run on both Linux and Windows servers Download the eBook. And on and on. In order to arrive at the answer you have to ask the same return question in each case: have you looked at the execution plan?

SQL Monitor's execution plans can help troubleshoot your painful queries, so you can quickly identify the problem. Find out more.