SQL Server Solutions Archive

This article explains the role of Triggers in SQL Server database, while also addressing the right way to use them in the database management system.

Triggers are a type of advanced storage procedure, which are written to perform actions in a table like UPDATE, DELETE or INSERT. Users often make the mistake of overusing Triggers which is the leading cause for issues in their system’s performance. It is very essential for the users to properly use Triggers, or they could end up losing their precious data.Learn The Role Of Triggers

What are Triggers?

Triggers are used for performing auditing actions, which helps in maintaining table integrity for native constraints like check constraints and foreign key or for performing processing tasks in other posts like DML.

How Triggers Work?

Triggers In SQL Server DatabaseWhen triggers are fired in a database, they go to the selected table and modify or audit the data that the users enter to change. Triggers are stored in virtual tables which consist of all the data before as well as after the modification. These tables are referred to as deleted and inserted. Whenever working with these tables users should ensure to work on them as a set. These tables basically record all the changes implemented by the user on the SQL database.

How and when they are used?

Triggers are operated under the scope of any sort of transaction in the database, so if a user were to update his/her table he/she would have to use Trigger in order to run the update command.

Note that the change in the auditing action will only be reflected, when the trigger is completed. In case the user is using multiple triggers at a time, the SQL server will lock download the database until all the pending triggers are completed.

Points to Keep in Mind while Working with Triggers

  • Users should note that triggers are responsible for extending the life of the transactions, so if you run multiple triggers at a time, the system will automatically lock the server which will prevent you from using any command.
  • Triggers can be very stealthy, which often make troubleshooting data problems more tedious and difficult.
  • Using Triggers for accomplishing common integrity can be a bad idea; they work on an extended transaction life.
  • Note that in case of integrity violation during a trigger transaction, the database can be prone to a potential risk of data damage. So make sure to wait for the system during these ROLLBACK of data modification else you might end up losing it all.
  • Users can use Native constraints in such situations as they are less likely to cause a ROLLBACK during any modification, even if there is any violation.

Common Trigger Code Mistakes

Usually while working with Triggers users often use its command to reflect changes in a single row. They assume trigger to work one by one, modifying a single row and then moving to the next row. Well fortunately, this is a false assumption and triggers can be used for multiple rows and columns at a time.

We recommend users to minimize the tasks by specifying the code, to avoid any troubleshooting data issues, because they can be a real pain to resolve. In case you notice data errors, always opt for an mdf recovery tool to avoid any data loss scenario.

Author Introduction:

Victor Simon is a data recovery expert in DataNumen, Inc., which is the world leader in data recovery technologies, including repair Access and sql recovery software products. For more information visit https://www.datanumen.com/

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In this article we learn about the Integrity Constraints feature in Database design, and how it helps users to safeguard what is entered in the database tables.

SQL Server databases are a storehouse of data, although the access to enter data in the database should be limited to only a few people, there are other measures as well that need to be taken to ensure only relevant data is entered in the tables. One such measure is making use of Integrity Constraints for SQL databases. Integrity constraints are nothing but a set of rules which are used to define what type of data can be entered in the database. A lot of the people think that just defining the cluster index and the primary key of the database in question is enough, but it’s not! You need to make use of integrity constraints as well.Integrity Constraints In SQL Server Database Design

Integrity Constraints in SQL Server

These are provided within the SQL Server database engine and are the most effective solution for checking database integrity. Constraints like UNIQUE, CHECK, DEFAULT, primary key, foreign key should all be defined so that there are no invalid entries made in the database due to undefined constraints. There are two broad categories in which the Integrity Constraints available in SQL Server can be divided, these are:

  • Column Level Constraints – These are the type of constraints that are specified immediately after CREATE TABLE statement is used for column definition.
  • Table Level Constraints – These are those types of constraints that are specified once the ALERT TABLE statement is used for defining all the columns.

Apart from these two broad categories of Integrity Constraints, there are multiple other types of Integrity constraints in SQL Server.

Types of Integrity Constraints in SQL Server

MS SQL Server provides you access to 5 different Integrity Constraints.

  1. Primary Key ConstraintPrimary Key Constraint – In a database, the primary key can be one or more columns from the database table that is used for providing a unique identification number for each record on the table. This constraint ensures that the value is neither duplicate, not null.
  2. Unique Key Constraint – In definition it is pretty much like the primary key constraint, the only difference here is that it can take up to one null value, but no duplicate value.
  3. Foreign Key Constraint – The foreign key field of a database table forms the primary key field for another table, this not only accepts several null values, but also duplicate values.
  4. Not Null Constraints – This is one of those constraints that ensure there are no null values in the columns that have been specified with not null value. It is through this constraint that all rows with a specified condition on no null values never have null values.
  5. Check Constraints – This is one of the general integrity constraints that specifies a given business rule to be applied on any given column of the table, to which all rows must adhere to.

With the help of the five integrity constraints mentioned above, it becomes easier for the user to ensure what goes in the database, and what doesn’t.

Besides investing time in database optimization, DBAs also need to constantly update their business continuity plans. Keeping a tool to repair mdf database files can go a long way in ensuring zero data loss in the event of a SQL crash.

Author Introduction:

Victor Simon is a data recovery expert in DataNumen, Inc., which is the world leader in data recovery technologies, including recover mdb and sql recovery software products. For more information visit https://www.datanumen.com/

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In this article we understand the Data Migration Assistant in SQL Server and how it helps when upgrading a SQL Server instance to Azure.

The Data Migration Assistant in SQL Server helps detect compatibility issues between the data platform in use, the more recent edition of SQL Server, and Azure databases, that you might be willing to update to. On the basis of this detection, it suggests the user a modern data platform to which they should update for better functionality of the database. Along with this suggestion, it also recommends the user regarding the performance improvements that will be needed for operating in the target environment. Thus allowing you to shift schemas, data, as well as all the uncontained objects from the current server to the target server. Given below are all the capabilities of the feature.Understand The Capabilities Of Data Migration Assistant

Assessment

All the on premises SQL Server instances that are to be migrated to Azure SQL databases are assessed for any potential issues that may affect the migration process. Along with the migration blocking issues, it is also able to detect which features are partially supported, and which ones are completely unsupported in the SQL server instance being used. Once these issues are detected, DMA also helps users with providing solution for dealing with them. The provided solutions contains multiple approaches, recommendations, and mitigation strategies.

Discovery

DMA is able to discover issues that not only disrupt the migration process, but also those that disrupt the on premises upgrade process for SQL Server. These are called the compatibility issues and are ranked in the given order.

  • Breaking Changes
  • Behavior Changes
  • Deprecated Changes

Discovering New Features

Along with discovering compatibility and other issues, DMA can also discover the new features that are present in the target SQL platform, and will prove to be beneficial for the database, once the upgrade is done. These are also known as feature recommendations and are ranked in the following order.

  • Performance
  • Security
  • Storage

Migrating On premises Instance to Modern Instance

Data Migration Assistant For Upgrading Your SQL Server EditionAn on premises SQL Server instance can be migrated to a compatible and modern instance that is either hosted on Azure Virtual Machine (AVM), or on premises, and can also be accessed using the on premises network that is in use. You can access the AVM through VPN,    and other technologies, as for the migration workflow, it can be used for migrating the components given below.

  • Data and Users
  • Server roles
  • Database schema
  • SQL Server logins and Windows Logins

Once the process of migration is complete applications can successfully establish the connection with target SQL databases. Making use of the DMA feature to ensure that the SQL Server edition in use is upto date and compatible with the platform it is supposed to be used with is crucial for a flawless user experience. Incompatibility between the two will not only lead to a non-user friendly atmosphere, but might also end up being the cause of an unexpected disaster. To ensure that you so not lose data due to one silly mistake, always make use of the Data Migration Assistant when to planning to migrate SQL Server databases. In the event you suspect data loss, run a specialized mdf repair tool.

Author Introduction:

Victor Simon is a data recovery expert in DataNumen, Inc., which is the world leader in data recovery technologies, including recover access and sql recovery software products. For more information visit https://www.datanumen.com/

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