Database development

Esat Erkec

SQL multiple joins for beginners with examples

October 16, 2019 by

In this article, we will learn the SQL multiple joins concept and reinforce our learnings with pretty simple examples, which are explained with illustrations. In relational databases, data is stored in tables. Without a doubt, and most of the time, we need a result set that is formed combining data from several tables. The joins allow us to combine data from two or more tables so that we are able to join data of the tables so that we can easily retrieve data from multiple tables. You might ask yourself how many different types of join exist in SQL Server. The answer is there are four main types of joins that exist in SQL Server. First of all, we will briefly describe them using Venn diagram illustrations:

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Dinesh Asanka
Transaction log usage after TRUNCATE TABLE statment is executed.

Truncate Table Operations in SQL Server

September 25, 2019 by

Truncating a table is removing all the records in an entire table or a table partition. TRUNCATE table is functionally similar to DELETE table with no WHERE clause. However, TRUNCATE table is much faster than DELETE with respect to the time and the resource consumptions which we will look at in this article. TRUNCATE statement removes the data by de-allocating the data pages in the table data. This means that TRUNCATE is similar to drop and re-create the table. Also, it records only the page de-allocations in the transaction log, not the row-wise as in DELETE statement.

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Ed Pollack
Sample form with validation errors that protect the underlying code from SQL injection attacks.

SQL Injection: Detection and prevention

August 30, 2019 by

Summary

With an understanding of what SQL injection is and why it is important to an organization, we can shift into a discussion of how to prevent it. We ultimately want systems where SQL injection is impossible or very difficult to pull off. We then want systems where exploiting bugs is slow, laborious, and likely to raise monitoring alarms within an organization when attempted. The trio of layered security, prevention, and alerting can provide an immense advantage against not only SQL injection, but other data security threats.

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