We often encounter terms like DDL, DML, DQL, DCL, and TCL when using relational database management systems (RDBMSs). But what do they mean?
In this article we’ll look at what DDL stands for and what it does.
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Signed vs Unsigned Integers
The integer data type is probably one of the more common data types when working with database management systems (and with computing in general). The integer is a numeric data type that allows us to store certain kinds of numbers.
More specifically, an integer is the number zero (0), a positive natural number (e.g. 1, 2, 3, …) or a negative integer with a minus sign (e.g. −1, −2, −3, …). Integers contain no decimal or fractional part.
However, many computing environments distinguish between signed integers and unsigned integers.
Let’s take a look at the difference between signed integers and unsigned integers.
What is a Comparison Operator?
Comparison operators are an important part of most programming languages.
Comparison operators are used to compare two expressions. The result is either true or false. It could also be unknown. This could also be represented by either 1, 0, or NULL, depending on the language. These are typically known as “Boolean expressions”.
When used with databases, comparison operators can be used inside your SQL queries to filter data to a certain criteria.
What is a CHECK Constraint?
In database terms, a CHECK constraint is a type of constraint that checks data before it enters the database.
CHECK constraints help maintain data integrity, because they prevent invalid data entering the database.
What is Collation in Databases?
In database systems, Collation specifies how data is sorted and compared in a database. Collation provides the sorting rules, case, and accent sensitivity properties for the data in the database.
For example, when you run a query using the ORDER BY clause, collation determines whether or not uppercase letters and lowercase letters are treated the same.
Collation is also used to determine how accents are treated, as well as character width and Japanese kana characters. Collation can also be used to distinguish between various ideographic variation selectors in certain collations (such as the Japanese_Bushu_Kakusu_140 and Japanese_XJIS_140 collations that were introduced in SQL Server 2017).
Different database management systems will provide different collation options. Depending on the DBMS, collation can be specified at the server level, the database level, the table level, and the column level. Collations can also be specified at the expression level (so you can specify which collation to use when you run a query), and at the identifier level.
“This Data” vs “These Data” – Which is Correct?
If you happen to read a lot of data-related material, you might occasionally find the word “data” being treated in different ways. In some cases you’ll see “this data is…” and in other cases “these data are…”. You might even think “they obviously made a mistake with their grammar”.
Not so fast!
What is OLAP?
OLAP (Online Analytical Processing) is a category of database processing that facilitates business intelligence.
OLAP provides analysts, managers, and executives with the information they need to make effective decisions about an organization’s strategic directions. OLAP can provide valuable insights into how their business is performing, as well as how they can make improvements.
What is OLTP?
OLTP (Online Transactional Processing) is a category of data processing that is focused on transaction-oriented tasks. OLTP typically involves inserting, updating, and/or deleting small amounts of data in a database.
OLTP mainly deals with large numbers of transactions by a large number of users.
What is Normalization?
Normalization is the process of organizing a database to reduce redundancy and improve data integrity.
Normalization also simplifies the database design so that it achieves the optimal structure composed of atomic elements (i.e. elements that cannot be broken down into smaller parts).
Also referred to as database normalization or data normalization, normalization is an important part of relational database design, as it helps with the speed, accuracy, and efficiency of the database.
RDBMS vs DBMS – What’s the Difference?
There’s a lot of confusion regarding the difference between an RDBMSs and a DBMS. I’ve even seen “RDBMS vs DBMS” forum posts where the accepted answer outlines the differences between RDBMSs and DBMSs, as though they were two distinct and different things.
However, this can be misleading.
The fact is, an RDBMS is a DBMS. But a DBMS is not always an RDBMS (but it often is).
So, is there a difference between an RDBMS and a DBMS or not? Is “RDBMS vs DBMS” the right way of looking at it, or is there more to it?