You will most likely declare a variable in the SQL Server and use it in the SQL Statements. You can use the DECLARE statement and specify the variable and datatype and optionally provide a default value.
For example , You can declare an NewEmployeeJobTitle variable using the DECLARE statement and provide a default value as ‘Chief Executive Officer’
DECLARE @NewEmployeeJobTitle nvarchar(50) = 'Chief Executive Officer';
This variable can later be used within the T-SQL Query.
use AdventureWorks2014 GO DECLARE @NewEmployeeJobTitle nvarchar(50) = 'Chief Executive Officer'; SELECT * FROM HumanResources.Employee WHERE JobTitle = @NewEmployeeJobTitle
You can declare a variable without assigning a value for it in which case , the variable value will be NULL.