PHP Developer Interview Questions for AI Training Work

I check whether the new functionality genuinely represents a specialization of the existing class's behavior, rather than extending purely to reuse some convenient methods, since inheritance used just for code reuse tends to create fragile coupling. If the relationship isn't a genuine 'is-a' relationship, I favor composition over inheritance instead.

I push business logic into dedicated service classes or the model layer rather than letting it accumulate in controllers, since controllers that absorb business logic over time become hard to test and reuse. I treat the controller's job as coordinating input and output, not implementing the actual logic.

I check the query's execution plan and whether it's actually using the indexes I expect, rather than guessing at the cause, since a slow query is often a missing index or an unnecessarily broad query pulling more data than the application actually needs. I also check whether the query is being run more times than necessary, like inside a loop, which is a common source of avoidable slowdown.

I look at how the data will actually be queried and updated, not just how it's conceptually structured, since a schema optimized for read patterns that don't match reality causes performance problems later. I also check for consistency with existing schema conventions in the application rather than introducing a different pattern for just one feature.

I try to add the new feature following clean separation even if the surrounding code doesn't, rather than matching the existing messy pattern purely for consistency, since gradually introducing better patterns is more realistic than a full rewrite. I avoid making the existing mess worse while I'm in that part of the codebase.

I'd check for differences between environments first, like data state, database configuration, or query caching, rather than assuming the code itself is broken, since environment-specific data or configuration differences are a common cause of behavior that only shows up in one environment. I'd compare the actual query being run in production against what I expect, since an ORM or query builder can sometimes generate a different query than expected.

I'd extract logic incrementally as I touch related code, moving it into the appropriate model or service layer, rather than attempting a large-scale refactor all at once, since a big-bang refactor on a codebase I don't fully understand yet risks introducing regressions. I'd prioritize the views with the most active development first, since that's where the payoff from cleaner separation is highest.

I'd prioritize converting the areas under active development or with the highest bug rate first, rather than attempting to rewrite the entire codebase at once, since a full rewrite carries significant risk and often stalls before completion. I'd establish clear conventions for new code so the codebase moves consistently toward the object-oriented pattern over time rather than accumulating more inconsistency.

A class had grown to handle several unrelated responsibilities, which meant a change for one purpose frequently caused unexpected bugs affecting another. I split it into separate classes aligned to single responsibilities, and the recurring bugs from unintended side effects largely stopped once the responsibilities were properly separated.

I had designed a schema using a single flexible table for several loosely related entity types to move quickly early on, but as the application grew, queries against that table became increasingly complex and slow. I migrated the entities into properly normalized tables, which meaningfully simplified the queries and improved performance, even though the migration itself took real effort.