A UNIQUE constraint is a rule we apply to one or more columns in a database table to ensure that the values in those columns are unique across all rows. This means that no two rows in the table can have the same value(s) in the column(s) where we’ve applied the UNIQUE constraint. It’s an essential tool for maintaining data integrity and preventing duplicate entries in our database.
what is
Introduction to Indexing in SQL
When working with databases, performance can be very important. This is especially true in production environments where the end users expect their queries and reports to be generated within seconds (or even milliseconds).
While blistering fast queries may be the norm with smaller datasets, as our databases grow larger and more complex, it can become much more of a challenge to keep our queries nice and snappy. When working with smaller datasets, it’s often possible to get lightning speed results even when not optimizing for speed. But as the datasets grow larger, we need more efficient tools and techniques to retrieve and manipulate data. One such tool is the index.
A Quick Look at the FACTORIAL() Function in PostgreSQL
In PostgreSQL, factorial() is a mathematical function that returns the factorial of a given integer. We pass the integer (it accepts bigint), and it returns the factorial as a numeric value.
In mathematics, the factorial is the product of all positive integers less than or equal to a given positive integer. It’s denoted by that integer and an exclamation point.
Concatenate Arrays in PostgreSQL with the || Operator
In PostgreSQL, we can use the || operator to concatenate two arrays. We can also use it to append or prepend a (compatible) non-array value to an array.
Understanding Domains in PostgreSQL
PostgreSQL offers a handy feature called domains that can greatly enhance data integrity and simplify database design. In this article, we’ll explore what domains are, how they work, and when to use them in our database projects.
A Quick Look at the MD5() Function in PostgreSQL
In PostgreSQL, the md5() function computes the MD5 hash of the specific text, and outputs the result in hexadecimal.
We pass the text as an argument when calling the function.
SQL for Beginners: 10 Must-Know Concepts to Kickstart Your Database Journey
SQL stands for Structured Query Language. It’s the go-to query language for most of us who develop relational databases. If you want to work with relational database management systems, learning SQL is pretty much non-negotiable. Especially if you want to become a SQL developer.
If you’re interested in becoming a SQL developer, here are ten essential SQL concepts that you need to learn.
A Quick Look at TO_HEX() in PostgreSQL
In PostgreSQL, we can use the to_hex() function to convert a number to its equivalent hexadecimal representation.
The function accepts the number as an integer or bigint, and it returns the result as a text representation of its hexadecimal equivalent.
Introduction to the Enum Data Type in SQL
The Enum (enumeration) data type in SQL is a specialised string object that allows us to define a list of predefined values for a column. This data type can be particularly useful when we want to restrict the possible values that can be stored in a specific column to a fixed set of options.
A Quick Look at the ASCII() Function in PostgreSQL
In PostgreSQL, we can use the ascii() function to get the numeric code of the first character of the argument.
When using UTF8, the function returns the Unicode code point of the character. Other multibyte encodings require an ASCII character.