Execute Dynamic SQL commands in SQL Server

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In some applications having hard-coded SQL statements is not appealing, because of the dynamic nature of the queries being issued against the database server. Because of this sometimes there is a need to dynamically create a SQL statement on the fly and then run that command. This can be done quite simply from the application perspective where the statement is built on the fly whether you are using ASP.NET , ColdFusion or any other programming language. But how do you do this from within a SQL Server stored procedure? SQL Server offers a few ways of running a dynamically built SQL statement. These ways are: Writing a query with parameters Using EXEC Using sp_executesql Writing a query with parameters This first approach is pretty straightforward if you only need to pass parameters into the WHERE clause of your SQL statement. Let’s say we need to find all records from the Customers table where City = ‘London’. This can be done easily as the following example shows.
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T-SQL: Optional Parameters in Select Query (Using ISNULL)

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Suppose, you have to make search in the database table having optional parameters. For example you have some application with advanced search UI where user does not have to fill all search criteria. We can make it with one small trick - using ISNULL function.


CREATE PROC Search
(
   @param1 INT = NULL
  ,@param2 INT = NULL
)
AS
BEGIN

  SELECT column1
    FROM table1
   WHERE column1 = ISNULL(@param1, column1)
     AND column2 = ISNULL(@param2, column2)

END

If the 1st param in ISNULL function is null - it returns 2nd parameter.

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