Stored Procedures in MySQL

Stored Procedures in MySQL

• MySQL supports stored procedures, which are subroutines stored in the database catalog.
• Applications can call and execute stored procedures using the CALL SQL statement.
• Stored procedures help avoid duplicating database code. This saves time and effort when making updates, adjusting query performance, or adding database operations (e.g., for logging, security).

Creating a Stored Procedure

• The CREATE PROCEDURE statement defines stored procedures.
• A procedure example is provided using the country_hos procedure (takes a continent as input):
  • DELIMITER // changes the statement delimiter from semicolon to double forward slashes.
  • CREATE PROCEDURE country_hos (IN con CHAR(20)) declares a procedure named country_hos that accepts input con as a character string of length 20.
  • BEGIN ... END // DELIMITER; shows the code block within the procedure.
  • SELECT Name, HeadOfState FROM Country WHERE Continent = con; selects data from the Country table based on the Continent matching the input.

Calling Stored Procedures

• To execute the country_hos procedure, the CALL statement can be used: CALL country_hos('Europe');

Advantages of Stored Procedures

• Typically increase application performance by compiling and storing the procedure in the database.
• MySQL compiles stored procedures on demand and caches them for each connection. Reusing a procedure within a connection improves efficiency.
• Reduce network traffic between application and database server by sending only the stored procedure name and parameters instead of lengthy SQL statements.

Security and Reusability

• Stored procedures are secure because database administrators can grant specific permissions to access them without needing to grant permissions on any database tables.
• Stored procedures are reusable and transparent to applications. Developers don't need to create functions for tasks already supported by the stored procedures.

Disadvantages of Stored Procedures

• Excessive use of stored procedures can significantly increase memory usage per connection.
• Excessive use of logical operations within stored procedures may increase CPU usage. Database servers are typically optimized for simpler operations.
• Designing procedures with complicated business logic can be challenging.

Debugging Stored Procedures

• Debugging stored procedures can be difficult, requiring specialized tools; MySQL doesn't have built-in debugging support.

Stored Procedure vs. Function

• Functions must return a value; stored procedures are optional.
• Functions typically only take input parameters; stored procedures can accept both input and output parameters.
• Functions can be called from procedures; procedures cannot typically be called from functions.
• Stored procedures use the CALL statement; functions are typically accessed via a SELECT statement.

This quiz covers the concepts of stored procedures in MySQL, including their creation and usage. Learn how to define and call procedures, as well as understand their benefits in managing database code. This knowledge is essential for effective database programming and optimization.