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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Returning Complex Data from User-Defined Functions

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Returning multiple values from a UDF can be done fairly easily in SQL Server, but we must return those values as a virtual table. The following very simple ParseEmail() function accepts an email address as an argument, parses it, and returns the username and domain separately:




create function EmailParse (@email varchar(1000))
returns @t table (UserName varchar(20), Domain varchar(20))
as
begin
    declare @i int

    select @i = charindex('@', @email,1);

    if (@i > 1)
        insert into @t values (left(@email,@i-1), substring(@email,@i+1,20))
    else
        insert into @t values (null,null)

    return
end


how to use

select username, domain
from   EmailParse('test@test.com')

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