Why do we use Exec in SQL

Quote:

Executes a command string or character string within a Transact-SQL batch, or one of the following modules: system stored procedure, user-defined stored procedure, CLR stored procedure, scalar-valued user-defined function, or extended stored procedure. The EXECUTE statement can be used to send pass-through commands to linked servers.

Example

EXEC sp_help; -- sp_help is a built in function. this command is used to execute sp_help.

like this stored procedures are executed by using EXEC command.

you sholud go though this link
https://msdn.microsoft.com/en-IN/library/ms188332.aspx[^]

Further to solutions 1 and 2 (and note it can be used for more than just stored procedures), you should read this post[^] and the articles linked within it - it discusses the differences between EXEC and sp_executesql and how the latter is better to avoid sql injection[^]