Where clauses in Laravel - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ component_behavior

intermediate

What is the output of this Laravel query builder code?

Consider this Laravel query builder snippet:

$users = DB::table('users')->where('age', '>', 18)->where('active', 1)->get();

What SQL query does this generate?

A SELECT * FROM users WHERE age >= 18 AND active = 1

B SELECT * FROM users WHERE age > 18 OR active = 1

C SELECT * FROM users WHERE age > 18 AND active = 1

D SELECT * FROM users WHERE age > 18

💡 Hint

Remember that chaining where() methods combines conditions with AND by default.

Chaining multiple where() calls in Laravel combines them with AND in the generated SQL query.

📝 Syntax

intermediate

Which option correctly uses a closure in a where clause?

You want to select users who are either active or have a role of 'admin'. Which Laravel query builder code is correct?

A DB::table('users')->where('active', 1)->orWhere(function($query) { $query->where('role', 'admin'); })->get();

B DB::table('users')->where(function($query) { $query->where('active', 1)->orWhere('role', 'admin'); })->get();

C DB::table('users')->where('active', 1)->orWhere('role', 'admin')->get();

D DB::table('users')->where(function($query) { $query->where('active', 1)->where('role', 'admin'); })->get();

💡 Hint

Use a closure to group conditions inside a where clause.

Using a closure inside where() groups the conditions inside parentheses in SQL, so the orWhere applies inside the group.

🔧 Debug

advanced

Why does this Laravel query throw an error?

Given this code:

DB::table('users')->where('age', '>', 18, '=', 'AND')->get();

Why does it cause an error?

A The get() method must be called before where(), causing an error.

B The operator '>' is invalid in where clauses and causes an error.

C The table 'users' does not exist, causing a runtime error.

D The where method only accepts four parameters; the fifth 'AND' is invalid and causes an error.

💡 Hint

Check the number of parameters the where method accepts.

The where method accepts only four parameters: column, operator, value, and boolean. Adding a fifth parameter causes a syntax error.

❓ state_output

advanced

What is the value of $count after this Laravel query?

Consider this code:

$count = DB::table('users')->where('status', '!=', 'inactive')->count();

What does $count represent?

A The number of users whose status is not 'inactive'.

B The number of users with a null status.

C The total number of users in the table regardless of status.

D The number of users whose status is exactly 'inactive'.

💡 Hint

The where clause filters rows where status is not 'inactive'.

The count() method returns the number of rows matching the where condition, so it counts users not marked 'inactive'.

🧠 Conceptual

expert

Which option best explains how Laravel handles multiple where clauses internally?

When chaining multiple where() calls in Laravel's query builder, how are these combined in the generated SQL?

A Each where() call adds a condition combined with AND, unless grouped with closures for OR or nested logic.

B Each where() call overwrites the previous condition, so only the last where applies.

C All where() calls are combined with OR by default, unless explicitly changed.

D Laravel converts all where() calls into separate queries and merges results in PHP.

💡 Hint

Think about how SQL combines multiple conditions by default.

Laravel chains where() calls by combining conditions with AND in SQL. To use OR or complex logic, closures or orWhere() are needed.