Describe the purpose of the `<cfstoredproc>` tag and how it differs from using `<cfquery>`.
The `<cfstoredproc>` tag in ColdFusion is used to execute stored procedures within a database. A stored procedure is a precompiled collection of SQL statements stored on the database server. Think of it as a function within your database that performs a specific task, like retrieving data, updating records, or performing calculations. The primary purpose of `<cfstoredproc>` is to call and execute these stored procedures, leveraging the benefits of database-side processing. This contrasts with `<cfquery>`, which directly executes SQL statements written within the ColdFusion code.
Here's a breakdown of the key differences:
`<cfstoredproc>`:
* Execution Location: The stored procedure executes *on the database server*. This means the SQL code is processed directly by the database engine, which is generally faster and more efficient, especially for complex operations. The ColdFusion server only sends the call to the stored procedure and receives the results.
* Code Location: The SQL code resides *within the database itself*, not within the ColdFusion application. This promotes code reusability; the stored procedure can be called from multiple ColdFusion pages or even other applications connecting to the same database.
* Security: Stored procedures can enhance security by encapsulating sensitive data access logic within the database. Users might have permissions to call the stored procedure but not directly access the underlying tables.
* Syntax: The `<cfstoredproc>` tag requires the `procedureName` attribute to specify the name of the stored procedure to execute. It can also include attributes like `datasource` to specify the database connection and `arguments` to pass parameters to the stored procedure. For example: `<cfstoredproc procedureName="GetCustomerOrders" datasource="MyDatabase" arguments="CustomerID = #form.CustomerID#"/>`.
* Result Handling: The results returned by the stored procedure are typically available in the `cfstoredproc.data` variable in ColdFusion.
`<cfquery>`:
* Execution Location: The SQL statements within `<cfquery>` are sent to the database server and executed *there*, but the SQL is embedded directly within the ColdFusion code.
* Code Location: The SQL code is *part of the ColdFusion application*. Each time the query is executed, the entire SQL statement is sent to the database.
* Performance: While `<cfquery>` can be efficient, it generally performs slower than `<cfstoredproc>` for complex operations because the entire SQL statement needs to be parsed and compiled each time it's executed by the database server. `<cfstoredproc>` benefits from the precompiled nature of stored procedures.
* Syntax: The `<cfquery>` tag contains the SQL statement directly within its body. For example: `<cfquery datasource="MyDatabase" name="GetCustomerOrders"> SELECT * FROM Orders WHERE CustomerID = #form.CustomerID# </cfquery>`.
* Result Handling: The results returned by `<cfquery>` are typically available in the `query` variable in ColdFusion.
In essence, `<cfstoredproc>` delegates the SQL execution to the database server, utilizing precompiled stored procedures for efficiency, reusability, and potentially enhanced security. `<cfquery>` embeds SQL directly within the ColdFusion code, offering more flexibility but potentially sacrificing performance for complex operations.