Which Considerations Are Crucial When Replacing mysql_ Functions with mysqli_ in PHP?

mysql_ to mysqli_ Function Replacement: Proceed with Caution

Despite the deprecation and removal of mysql_ functions in PHP, their direct replacement with mysqli_ counterparts is not advisable. While some functions may share similar names, they are not exact equivalents and require targeted changes for seamless migration.

Connection Handling
The primary change involves establishing the database connection. In mysql_, the connection was typically a global variable. However, mysqli_ requires explicitly assigning the connection to a PHP variable and using it as an argument in all subsequent mysqli_ functions.

Query Execution
Query execution in mysqli_ differs from mysql_. The mysqli_query() function takes the connection as its first argument in procedural code, while in object-oriented code, it is invoked as a method on the connection object.

Result Fetching
Fetching results using mysqli_ retains the same pattern as mysql_. However, it offers the flexibility of using either procedural or object-oriented syntax. The result set can be accessed via the object method fetch_assoc() in object-oriented style.

Additional Considerations
Apart from the discussed functions, other mysql_ functions like error handling and connection closing also require explicit inclusion of the connection variable or object reference. It is essential to review the entire codebase and adapt any custom functions accordingly.

Recommended Approach
While blindly replacing mysql_ functions with mysqli_ may not lead to immediate errors, it can introduce subtle bugs in the long run. A systematic review and tailored conversion of code segments are recommended. Additionally, consider embracing object-oriented techniques for improved code organization and extendability.

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