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Locking in SQL Server

Locking in SQL Server is mechanism to control and manage concurrency maintaining data integrity and validation. This allows multiple users to access  and use database concurrently. Consider the scenario and let me paint the complete picture here. When we talk about concurrency in DBMS , we are talking about DBMS allowing multiple users conducting multiple transactions and operations all at the same time. The operation can be read , update , delete or create. All of this , should execute on correct data. If Transaction T1 updates a row transaction T2 should be able to read the updated data. All ...
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SQL Server Isolation Levels

SQL Server Isolation Levels helps in concurrency & transaction management by preventing concurrency problems . In an environment where we have multiple users modifying and accessing the same information , it is essential that they all can work at the same time without any delays. They all should be able to read correct data and modify data at will. Also see : SQL Server Concurrency & Transaction Management Commit & Rollback In transaction's ACID Properties we talked about , how a transaction has to change the state of the database and complete it's task and leave the system in a ...
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SQL Server Concurrency & Transaction Management

SQL Server Concurrency & Transaction Management  is a process which allows multiple users to access data and perform multiple operations maintaining data integrity and smooth execution all at the same time. Microsoft SQL Server manages concurrency control by using locks to help protect data. The locks control how multiple users can access and change shared data at the same time without conflicting with each other. This a concept which needs to be in developer's mind all the time while writing the scripts to avoid any problems that may occur due to execution. Such as data loss , dirty reads and deadlocks ...
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SQL Subquery | SQL Beginner Guide

SQL Subquery is another tool SQL Server has which can be used to fetch data from other tables to be used in main query according to the needs.  Inner query and nested query are other names of SQL Subquery. SQL Subquery can be used with the SELECT, INSERT, UPDATE, and DELETE statements along with the operators like =, <, >, >=, <=, IN, BETWEEN, etc. The idea is that a subquery returns data for one column which can be further utilised in outer query. Too much to read , let's just start with examples and we will clear the points as ...
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How Grouping Works in SQL

One of our subscribers reached us and asked How Grouping works in SQL ?  So today , this is what we are going to do . We will discuss in detail about grouping in SQL and how it actually works behind the scenes. Also , this is our first post in Questions category and we will be doing more as there are bundle of requests in the queue. So if you want to contribute and like us to write something for you , please do not hesitate. How Grouping works in SQL? Grouping summarises the whole data set into smaller chunks ...
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MS SQL Query Execution Order Examples | SQL Beginner Guide

MS SQL Query Execution Order or SQL order of operations determines the sequence in which SQL clauses are executed by database engine . This helps in writing the error free and optimised queries .This SQL Query Processing is applied from a basic query to a thousands lines of queries , our database engine uses this execution order . See below the MS SQL Query Execution Order FROM ON OUTER WHERE GROUP BY HAVING SELECT DISTINCT ORDER BY TOP Also see : SQL SELECT Query & Statements Recommended : MS SQL Group By Clause Also see : MS SQL Having Clause One ...
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MS SQL Having Clause | SQL Beginner Guide

Filtering the Groups in MS SQL ( Transact SQL-TSQL)  requires MS SQL Having clause . We discussed in detail about sets & groups in our post on Group by clause.   In order to be able to practice the examples that we will discuss , i recommend you to use our sample database. It's a script you just have to copy paste in your MS SQL Server Management Studio & everything will be ready. Also see : How to Install MS SQL Server Management Studio  MS SQL Having Clause MS SQL Having clause is used to apply a filter on groups that are formed ...
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MS SQL Group By Clause | SQL Beginner Guide

MS SQL Group By Clause in SQL is used with aggregate functions to group data based on columns. Before , we jump to details of the Group By clause let's try to understand about grouping. SQL is based on set-theory and whenever you're composing a query you treat a table as a whole & not row-by-row. Similarly , when we use aggregate functions we have to group the sets . This way you will have aggregated view of the set. What is the Difference Between a Group & Set? What is a SET in SQL A set is collection of ...
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SQL Server Aggregate Functions | SQL Beginner Guide

SQL Server offers several built-in functions. SQL Aggregate functions are among the ones most widely used in reporting & data joining scenarios. Following are few SQL Aggregate functions we will discuss today COUNT ()                  returns the total number of values in a given column SUM ()                       returns the sum of the numeric values in a given column AVG  ()                       returns the average value of a given column MIN()          ...
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Stored Procedure And Function In SQL With Example

Stored Procedure And Function In SQL With Examples is the topic for today . Hello future & present database experts let's  discuss What is Stored Procedure in SQL Stored Procedure Syntax How to run Stored Procedure in SQL User-Defined Functions & SQL Functions. Difference between Stored Procedures & Functions in SQL Server. We will take SQL Server Stored Procedure Example & Function Example from our sample database.  I recommend you create this database. It will help you in a better understanding of this tutorial. Let's cut to chase now & learn SQL Stored Procedures first. What is Stored Procedure in SQL ...
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What Is View In SQL

In SQL one of the very useful database object is View.  We will learn SQL CREATE VIEW , ALTER VIEW & DROP VIEW Statements today with the conceptual understanding of it as well. Now , If you have our College database you can do basic SQL queries practice . You can use our Sample College Database script & generate one database in your system. SQL View                               View is the virtual table formed as a result of a query Word Virtual needs an explanation , so ...
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Features Of Database Management System?

We have all heard so much about Database management systems that sometimes we confuse the two things. One is RDBMS which is  Dr. Codd's data model which has 12 rules & the other is the software which is used to manage the RDBMS. Since , we humans love acronyms & like to shorten down everything these two terms are often used together . We have removed R from RDBMS  and started to use DBMS . Trust me it does confuse even the experienced people sometimes. Because S in both terms have different meaning. For RDBMS it is System and for ...
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Professional Data Analyst and Business Intelligence Developer with experience of delivering industrial projects for Supply Chain and Insurance Industry . Sharing all my experience and insights in databases and data warehousing and open to learn from fellows ! Happy Reading and Learning!