Understanding SQL Server Identity for Devs

Greetings Devs! As a developer, you know how important it is to have a clear understanding of the database server and its components. One such component is SQL Server Identity. In this article, we will walk you through everything you need to know about SQL Server Identity and its usage in database development.

What is SQL Server Identity?

SQL Server Identity is a property that is used to create an Auto-Generated, Numeric, and Unique value for a column in the database table. This value will be generated by the SQL Server Identity property, which can be applied to any numeric column of the table such as integer, decimal, or numeric column.

You can use the SQL Server Identity property when you are creating a table in SQL Server, and you want to generate a unique value for a specific column. SQL Server Identity is useful when you want to control the number of records in the table and maintain the uniqueness of the values generated.

The SQL Server Identity property can be applied to multiple columns of a table, but it is recommended to use it on a primary key column of the table.

How does SQL Server Identity work?

SQL Server Identity works by generating a unique value for each new row that is added to the table. The SQL Server Identity property is set up to increment the value by one each time a new row is added to the table. The first value generated by SQL Server Identity is the seed value, which is set by the developer. The seed value determines the starting value for the identity column.

For instance, if the seed value is 100, then the first value generated by SQL Server Identity will be 100, and each subsequent value will be incremented by one.

Additionally, the increment value is also set by the developer. The increment value determines the increment at which SQL Server Identity will increase the value of the identity column. For example, if the increment value is 2, then the value generated by SQL Server Identity will increase by two for each new row that is added to the table.

Creating a SQL Server Identity Column

Creating a SQL Server Identity column is a straightforward process. You can add the SQL Server Identity property to the column when creating a new table or modify an existing table. Here is how to create a SQL Server Identity column:

Once the table is saved, the SQL Server Identity property will generate a unique value for the identity column for each new row that is added to the table.

FAQs about SQL Server Identity

1. Can the SQL Server Identity column be updated?

No, the SQL Server Identity column cannot be updated. The SQL Server Identity column generates a unique value for each new row that is added to the table, and its value cannot be changed.

2. Is it possible to change the Seed or Increment value after the table is created?

Yes, it is possible to change the Seed or Increment value after the table is created. You can use the ALTER TABLE statement to modify the Seed or Increment value.

3. Can I use SQL Server Identity for non-numeric columns?

No, SQL Server Identity can only be used for numeric columns such as integer, decimal, or numeric column.

4. What is the maximum value for SQL Server Identity?

The maximum value that can be generated by SQL Server Identity is 2,147,483,647. After this value is reached, SQL Server will return an error message stating that the maximum value has been exceeded.

5. Does SQL Server Identity guarantee uniqueness?

Yes, SQL Server Identity guarantees uniqueness for each new row that is added to the table. The SQL Server Identity property generates a unique value that is incremented by one for each new row added to the table.

Conclusion

SQL Server Identity is a valuable property that can be used to generate a unique value for a column in a database table. The SQL Server Identity property guarantees uniqueness and is essential for maintaining the integrity of the data in the table. As a developer, it is crucial to have a clear understanding of SQL Server Identity and its usage in database development.