SQL commands

Emil Drkusic

Learn SQL: How to Write a Complex SELECT Query

February 4, 2020 by

In my career, I’ve heard many times, things like “How to write a complex SELECT query?”, “Where to start from?” or “This query looks so complex. How you’ve learned to write such complex queries?”. While I would like to think of myself as of a brilliant mind or genius or add something like “query magician” to my social network profiles, well, writing complex SQL wouldn’t be the only thing required to do that. Therefore, in this article, I’ll try to cover the “magic” behind writing complex SELECT statements.

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Prashanth Jayaram
The trend which proves the SQL is third top used tool

Introduction to SQL

January 29, 2020 by

Today, data is the basis of any business. The world of enterprise computing is the epitome of data-driven businesses. The importance of structured storage of data is unquestionably in the focus. And at this time, with the computing model quickly shifting towards the cloud, and storage costs falling rapidly, enterprises are leveraging data more and more to tune their businesses.

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Emil Drkusic
aggregate functions - the data model we'll use

Learn SQL: Aggregate Functions

January 28, 2020 by

SQL has many cool features and aggregate functions are definitely one of these features, actually functions. While they are not specific to SQL, they are used often. They are part of the SELECT statement, and this allows us to have all benefits of SELECT (joining tables, filtering only rows and columns we need), combined with the power of these functions.

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Emil Drkusic
join multiple tables - tables needed

Learn SQL: Join multiple tables

January 27, 2020 by

If you want to get something meaningful out of data, you’ll almost always need to join multiple tables. In this article, we’ll show how to do that using different types of joins. To achieve that, we’ll combine INNER JOINs and LEFT JOINs. So, let’s start.

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Bojan Petrovic
CREATE VIEW SQL script for creating a simple view

CREATE VIEW SQL: Creating views in SQL Server

January 23, 2020 by

Introduction

In this article, we are going to see how to use the CREATE VIEW SQL statement to create a view. This is the first article in a series that will be a programmatical approach of creating, altering and working with views using T-SQL. If you are a beginner and you don’t even know what a view is, don’t worry. We will kick off with a definition, and then move on to some basics like syntax, examples, use cases, etc.

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Emil Drkusic
SQL - types of relations

Learn SQL: Types of relations

January 22, 2020 by

One of the most important things in databases is to understand the types of relations in the databases. That stands for both – a process of designing a database model as well as when you’re analyzing your data. Understanding these relations is somehow natural and not so complex but is still essential in the database theory (and practice).

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Emil Drkusic

Learn SQL: SQL Scripts

January 21, 2020 by

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.

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Emil Drkusic

Learn SQL: SELECT statement

January 13, 2020 by

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.

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Esat Erkec

Introduction to the sp_executesql stored procedure with examples

January 9, 2020 by

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.

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Emil Drkusic

Learn SQL: Foreign Key

January 7, 2020 by

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.

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Esat Erkec

An overview of the STRING_AGG function in SQL

January 3, 2020 by

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.

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Emil Drkusic

Learn SQL: Primary Key

December 20, 2019 by

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.

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Jignesh Raiyani
Ranking Function Query with Result

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

December 19, 2019 by

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.

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Emil Drkusic

Learn SQL: INSERT INTO TABLE

December 12, 2019 by

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.

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