Information security, whether in databases, applications, or larger IT systems, is based on the principles of Authentication and Authorization, often referred to as AuthN and AuthZ respectively.
Likewise, PostgreSQL security involves creating roles that allow access to server resources (AuthN) and then granting privileges to database objects appropriately (AuthZ). Understanding how each of these components work together is essential to effectively manage security in a PostgreSQL cluster.… Read more
Once data is in a table it needs to be maintained. New records will need to be added, and existing records will need to be updated, and/or deleted. To keep data maintained, the insert, update or delete actions may need to be performed. This article will show how those three data manipulation language (DML) actions can be synchronized together within a single basic MERGE statement.… Read more
As with any other relational data management system (RDBMS), PostgreSQL uses indexes as a mechanism to improve data access. PostgreSQL has a number of different index types, supporting different behaviors and different types of data. In addition, again, similar to other RDBMS, there are properties and behaviors associated with these indexes.
In this article I’m going to go over the different types of indexes and some index behaviors. We’ll get into what the indexes are, how they work, and how best you can apply them within your databases. I’m hoping you’ll develop an understanding of which indexes are likely to work better in each situation.… Read more
As with many relational database management systems, MySQL provides a variety of methods for combining data in a data manipulation language (DML) statement. You can join multiple tables in a single query or add subqueries that pull data in from other tables. You can also access views and temporary tables from within a statement, often … Read more
In this article, I want to talk about a topic that you may never need. The only time I have really had need to look at the bits in a byte pattern. In (what is now) ancient versions of SQL Server didn't have such self-describing columns like in its metadata objects like it does now.… Read more
A subquery is a type of query that is embedded—or nested—into a data manipulation language (DML) statement. The data returned by the subquery is passed into the DML statement and incorporated into its overall logic. The subquery itself is typically a SELECT statement, although you can also use a TABLE statement or VALUES statement. Even so, the SELECT statement continues to be the most common choice for subqueries, and that’s the one I focus on in this article.… Read more
If only the entire world used UTC, wouldn’t life be so much easier? We can dream, can’t we? While some software applications can live in an ecosystem where all dates and times can be stored in a single time zone with no conversions needed, many cannot. As applications grow and interact more with international customers, … Read more
In the last few articles in this series, you learned about three important data manipulation language (DML) statements: SELECT, INSERT, and UPDATE. The statements make it possible to retrieve, add, and modify data in a MySQL database. Another DML statement that is just as important is DELETE, which lets you remove one or more rows from a table, including temporary tables. In this article, I focus exclusively on the DELETE statement to help round out our discussion on the core DML statements in MySQL. Overall, the DELETE statement is fairly basic, but one that’s no less necessary to have in your arsenal of DML tools.
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Over time data in SQL Server tables needs to be modified. There are two major different aspects of modifying data: updating and deleting. In my last article “Updating SQL Server Data” I discussed using the UPDATE statement to change data in existing rows of a SQL Server table. In this article I will be demonstrating … Read more
In the previous two articles in this series, you learned about SELECT and INSERT, two important data manipulation language (DML) statements in MySQL. In this article, I focus on the UPDATE statement, another valuable DML statement in MySQL.… Read more
The previous installment of this series examined aggregate subquery removal and subquery coalescing, describing the latter as similar in some ways to an inverse for “Or Expansion” and “Join Factorization”. In this instalment, it’s time to take a closer look at Or Expansion and we’ll move on to Join Factorization in the next instalment.… Read more
Once data is inserted into a table, data typically needs to be maintained as time goes on. To make changes to an existing row or a number of rows, in a table, the UPDATE statement is used. This article shows how to use the UPDATE statement to modify data within a SQL Server table. Syntax … Read more
mysqldump is one of the most popular database backup tools in the MySQL world. The tool is prevalent partly because it’s very basic and quite powerful – mysqldump database backup tool is command line-based, very simple and very straightforward to use. As far as MySQL or its flavors (MariaDB and Percona Server) are concerned, this … Read more
In the previous article in this series, I introduced you to the SELECT statement, one of several SQL statements that fall into the category of data manipulation language (DML), a subset of statements used to query and modify data. Another DML statement is the INSERT statement, which lets you add data to MySQL tables, both … Read more
Before data can be read from of a SQL Server database table, the table needs to contain rows of data. One of the most typical ways to get data into a table is to use the INSERT statement. One row or multiple rows can be inserted with a single execution of an INSERT statement. You … Read more
In order to test graph structures, I needed a large set of random data. In some ways, this data will resemble the IMDB database I will include later in this chapter, but to make it one, controllable in size and two, random, I created this random dataset. I loaded a set of values for an … Read more
There’s more to security in MySQL than user account privileges. In this article, Lukas Vileikis explains the other components of MySQL security.… Read more
During Build 2022, Microsoft announced a new feature, Datamarts for Power BI. MVP Dennes Torres explains this new feature and provides and example. … Read more
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