Why I have to use stored procedures?

For security

They are precompiled and is stored in Database. SP's reduces the Server load to Compile the Queries.

Simple sql queries complied every time during execution but stored procedures are precomplied hence the execution time of execution is reduced.

If there is a situation where we write a query again and again then we write that query as stored procedure and we call it by its name.

store procedure is compiled statement that why is faster and also it is more secure

A benefit of stored procedures is that you can centralize data access logic into a single place that is then easy for DBA's to optimize. Get DataBase result sets from some business logic on data. Execute multiple DB operation at single call.

Stored Procedure can reduce network traffic. An operation requiring hundreds of lines of Transact-SQL code can be performed through a single statement that executes the code in a procedure, rather than by sending hundreds of lines of code over the network

Stored procedure are precompiled objects. so execution time is much better than inline queries.

1. Stored procedures are used for performance factor 2. Also Stored procedures are secure than Inline queries