Integrity Constraints in SQL Server – Everything You Need to Know

admin | Published: July 7, 2020 | SQL, SQL Server 2016 |

SQL Server databases are a storage facility of data, in spite of the fact that the entrance to enter data in the database ought to be restricted to just a couple of individuals, there are different measures also that should be taken to guarantee just applicable data is entered in the tables. One such measure is using Integrity Constraints in SQL Server for SQL databases. Honesty requirements are only a lot of rules which are used to characterize what sort of data can be entered in the database. A lot of the individuals imagine that simply characterizing the clustered index and the primary key of the database being referred to is sufficient, yet it’s definitely not! You have to use integrity constraints also.

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What Are Integrity Constraints in SQL Server

Integrity constraints in SQL Server are that helps to maintain the Quality of information. It ensures that the data insertion, deletion has to be performed in this way like the data integrity is not affected. It also helps to protect the accidental damage to the database.

These are given inside the SQL Server database motor and are the best answer for checking database honesty. Requirements like UNIQUE, CHECK, DEFAULT, Primary key, the Foreign key should all be characterized so that there are no invalid entries made in the database because of indistinct constraints. There are two general classifications in which the Integrity Constraints accessible in SQL Server can be partitioned, these are:

  • Column Level Constraints – These are the sort of requirements that are determined following the CREATE TABLE explanation is used for a column definition.
  • Table Level Constraints – These are those sorts of constraints that are determined once the ALERT TABLE articulation is utilized for characterizing all the columns.

Aside from these two general classes of Integrity Constraints, there are numerous different sorts of Integrity constraints in SQL Server.

Sorts of Integrity Constraints in SQL Server

MS SQL Server gives you access to 5 distinctive Integrity Constraints.

  1. Primary Key Constraint – In a database, the primary key can be at least one column from the database table that is used for giving a unique distinguishing proof number to each record on the table. This requirement guarantees that the worth is neither copy, not invalid.
  1. Unique Key Constraint – In the definition it is practically similar to the primary key imperative, the main contrast here is that it can take up to one invalid worth, however no copy esteem.
  1. Foreign Key Constraint – The foreign key field of a database table structures the primary key field for another table, this acknowledges a few null values, as well as copy, esteems.
  1. Not Null Constraints – This is one of those requirements that guarantee there are no null values in the columns that have been indicated with no null value. It is through this constraint that all rows with a predefined condition on no null values never have null values.
  1. Check Constraints – This is one of the general integrity constraints that indicate a given business rule to be applied on some random column of the table, to which all rows must stick to.

With the assistance of the five Integrity constraints referenced above, it gets simpler for the client to guarantee what goes in the database, and what does not.

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Also Read: Know About Recovery Model in SQL Server.

Conclusion

To enter and check what type of database to be entered in the database the integrity constraints play a vital role. So, in this blog, we have studied what is Integrity constraints and how to use Integrity constraints in SQL Server? Moreover, we have also discussed the types of Integrity constraints. Also, if your SQL database file is damaged or corrupted, then we have also mentioned the best tool to fix the SQL Server database files.