SQL commands

Understanding the interaction between Set Theory and Set Operators in SQL Server

January 21, 2020 by Esat Erkec

In this article, we will describe the relation between the Set Theory and SQL Server Set Operations

Learn SQL: SQL Scripts

January 21, 2020 by Emil Drkusic

I can hardly imagine making any complex database changes without using SQL scripts. We actually used them in this series so far, but we haven’t pointed out what they actually are. Today we’ll stand up against that injustice. Sit back, relax, and get ready to learn something new and useful.

Learn SQL: INNER JOIN vs LEFT JOIN

January 16, 2020 by Emil Drkusic

INNER JOIN vs LEFT JOIN, that is the question. Today, we’ll briefly explain how both of these two join types are used and what is the difference. We’ll go through this topic again later when we’ll expand our model and be able to write much more complex queries.

An overview of the CONCAT function in SQL with examples

January 13, 2020 by Esat Erkec

In this article, we will explore the syntax, working mechanism and other details of the CONCAT function in SQL and we will also make up various different examples about it.

Learn SQL: SELECT statement

January 13, 2020 by Emil Drkusic

The SELECT statement is probably the most important SQL command. It’s used to return results from our database(s) and no matter how easy that could sound, it could be really very complex. In this article, we’ll give an intro to the SELECT statement and we’ll cover more complex stuff in the upcoming articles.

Introduction to the sp_executesql stored procedure with examples

January 9, 2020 by Esat Erkec

The sp_executesql is a built-in stored procedure in SQL Server that enables to execute of the dynamically constructed SQL statements or batches. Executing the dynamically constructed SQL batches is a technique used to overcome different issues in SQL programming sometimes. For example, when we want to determine the displayed columns in our reports, this procedure might be a solution option for us. In the simplest sense, this procedure takes a dynamically constructed SQL batch and other parameters, then execute it in the runtime and, finally, it returns the result.

Learn SQL: Foreign Key

January 7, 2020 by Emil Drkusic

In the previous article, we talked about the primary key (PK). In this one, we’ll check what is the foreign key (FK) and how it’s related to the primary key. This is the final step, after creating tables, inserting data, and defining primary keys, to cover all basics related to the database theory. There is much, much more than this, but if you understand these concepts, everything else is just expanding your knowledge around these basics.

An overview of the STRING_AGG function in SQL

January 3, 2020 by Esat Erkec

In this article, we will explore the STRING_AGG function in SQL and we will also reinforce our learning with various examples. STRING_AGG function can be counted as a new member of the SQL aggregation functions and it was announced in SQL Server 2017. STRING_AGG function gathers all expression from rows and then puts it together in these rows expression in order to obtain a string. Additionally, this function takes a separator parameter that allows separating the expressions to be concatenated.

Rollback SQL: Rolling back transactions via the ROLLBACK SQL query

December 26, 2019 by Ben Richardson

The rollback SQL statement is used to manually rollback transactions in MS SQL Server.

Understanding the SQL EXCEPT statement with examples

December 23, 2019 by Ben Richardson

The SQL EXCEPT statement is one of the most commonly used statements to filter records when two SELECT statements are being used to select records.

The SQL EXCEPT statement returns those records from the left SELECT query, that are not present in the results returned by the SELECT query on the right side of the EXCEPT statement.

Learn SQL: Primary Key

December 20, 2019 by Emil Drkusic

If you’ve already worked with databases, then you could hardly miss the term – Primary Key (PK). And if you’re reading this series and use it to learn about databases, well, this article should give you a good overview of what the PK really is. Still, if you’re a database expert, maybe you’ll find something new or just refresh your knowledge. So, sit back, relax, and let’s dive into PKs.

Replace a SQL While loop and a cursor with ranking functions in SQL Server for better query performance

December 19, 2019 by Jignesh Raiyani

SQL While loop and cursor are the most common approach to repeat a statement on condition-based or determined limits. Loop and cursor can be utilized in a circumstance to deal with row-based processing in T-SQL. We generally observe moderate execution of old made procedures, which are composed of using loop and cursors. Those procedures take time, especially when the number of iteration count is big for the execution.

How to create a view in SQL Server

December 16, 2019 by Esat Erkec

In this article, we will learn the basics of the view concept in SQL Server and then explore methods to create a view in SQL using T-SQL and SQL Server Management Studio.

Learn SQL: INSERT INTO TABLE

December 12, 2019 by Emil Drkusic

In the previous article, we’ve created two tables, and now we’re ready to use the SQL INSERT INTO TABLE command and populate these tables with data. In order to do so, we’ll prepare statements in Excel and then paste these statements into SQL Server and execute them. We’ll also check the contents of both tables before and after these commands using the SELECT statement. So, let’s start.

An overview of SQL Server data types

December 9, 2019 by Rajendra Gupta

In this article, we will give an overview of various SQL Server data types.

An overview of the SQL Server Update Join

December 5, 2019 by Rajendra Gupta

This article explores the SQL Server Update Join statement in T-SQL for SQL Server.

Learn SQL: CREATE DATABASE & CREATE TABLE Operations

December 5, 2019 by Emil Drkusic

Welcome to the first article in the Learn SQL series. In this part, we’ll start with two essential commands in SQL: Create Database and Create Table. While both are pretty simple, they should be used first before you start working anything with data (unless you use some template database).

The Table Variable in SQL Server

December 3, 2019 by Esat Erkec

In this article, we will explore the table variable in SQL Server with various examples and we will also discuss some useful tips about the table variables.

SQL Variables: Basics and usage

November 18, 2019 by Esat Erkec

In this article, we will learn the notions and usage details of the SQL variable. In SQL Server, local variables are used to store data during the batch execution period. The local variables can be created for different data types and can also be assigned values. Additionally, variable assigned values can be changed during the execution period. The life cycle of the variable starts from the point where it is declared and has to end at the end of the batch. On the other hand, If a variable is being used in a stored procedure, the scope of the variable is limited to the current stored procedure. In the next sections, we will reinforce this theoretical information with various examples

Read SQL Server error logs using the xp_readerrorlog command

November 14, 2019 by Rajendra Gupta

This article explores the xp_readerrorlog command for reading SQL Server error logs using T-SQL.

SQL OFFSET FETCH Feature: Loading Large Volumes of Data Using Limited Resources with SSIS

November 14, 2019 by Hadi Fadlallah

In this article, we illustrate how to use the OFFSET FETCH feature as a solution for loading large volumes of data from a relational database using a machine with limited memory and preventing an out of memory exception. We describe how to load data in batches to avoid placing a large amount of data into memory.