Raw expressions in Laravel - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of raw expression in a query builder

What will be the output SQL query generated by this Laravel query builder code?

Laravel

$query = DB::table('users')
    ->select(DB::raw('count(*) as user_count'))
    ->toSql();
echo $query;

A select count(*) as user_count from users

B select count(*) as user_count from `users`

C select count(*) user_count from `users`

D select count(*) from `users`

💡 Hint

Remember Laravel adds backticks around table names in the generated SQL.

Laravel's query builder wraps table names with backticks and preserves raw expressions as-is. So the raw count(*) as user_count remains unchanged, and the table name is backticked.

❓ component_behavior

intermediate

Effect of raw expressions on query bindings

Given this Laravel query, what will be the value of the bindings array after execution?

Laravel

$query = DB::table('orders')
    ->whereRaw('price > ?', [100])
    ->where('status', '=', 'paid');
$bindings = $query->getBindings();

A [100, 'paid']

B ['paid', 100]

C [100]

D ['paid']

💡 Hint

Bindings are collected in the order they appear in the query.

The whereRaw adds a binding for 100 first, then the where adds a binding for 'paid'. So the bindings array is [100, 'paid'].

🔧 Debug

advanced

Why does this raw expression cause a syntax error?

Consider this Laravel query: DB::table('products') ->select(DB::raw('SUM(price) AS total_price')) ->whereRaw('category = ?', 'electronics') ->get(); Why does this code cause an error?

A The DB::raw expression is missing parentheses around SUM(price)

B The table name 'products' must be wrapped in backticks in DB::table

C The select method cannot accept raw expressions

D The whereRaw method expects the second argument to be an array, not a string

💡 Hint

Check the expected argument types for whereRaw bindings.

whereRaw expects the bindings as an array. Passing a string causes a type error.

📝 Syntax

advanced

Correct syntax for raw order by clause

Which option correctly orders users by a raw expression that calculates length of the name?

Laravel

DB::table('users')->orderByRaw(???)->get();

A 'LENGTH(name) DESC'

B LENGTH(name) DESC

C ['LENGTH(name) DESC']

D DB::raw('LENGTH(name) DESC')

💡 Hint

orderByRaw expects a string with the raw SQL expression.

orderByRaw takes a string. Passing a bare expression or array causes errors.

🧠 Conceptual

expert

Understanding security risks with raw expressions

Which statement best explains the security risk when using raw expressions in Laravel queries?

A Using raw expressions disables all query logging in Laravel

B Raw expressions automatically sanitize all inputs to prevent SQL injection

C Raw expressions can introduce SQL injection if user input is concatenated directly without bindings

D Raw expressions prevent Laravel from caching query results

💡 Hint

Think about how raw SQL is handled compared to parameter binding.

Raw expressions bypass Laravel's query builder protections. If user input is concatenated directly, it can cause SQL injection.