PromptHub
Back to Errors
Laravel Intermediate 318 views

QueryException (SQL Errors)

A database query failed due to invalid SQL, constraint violations, or connection issues.

Explanation

QueryException is thrown by Laravel's database layer when a SQL query fails. This can happen for many reasons including syntax errors in raw queries, foreign key constraint violations, unique constraint violations, or database connection issues. The exception message includes the raw SQL query that failed, making it easier to debug. Common scenarios include inserting duplicate values into unique columns, referencing non-existent foreign keys, or using database-specific syntax that your database driver doesn't support.

Common Causes

  • Unique constraint violation
  • Foreign key constraint failure
  • Invalid SQL syntax
  • Database connection lost
  • Column type mismatch

Solution

Read the QueryException message carefully to identify which SQL query failed and why. Use DB::enableQueryLog() and dd(DB::getQueryLog()) to inspect queries during development. For constraint violations, ensure referenced records exist before inserting or updating. Use database transactions for operations that involve multiple related queries. Add proper database indexes for frequently queried columns. Test raw SQL queries directly in your database client to verify they work.

Code Example 

// This can throw QueryException if email already exists
User::create(['email' => 'existing@example.com', 'name' => 'John']);

// Fix: Use findOrCreate for idempotent operations
$user = User::firstOrCreate(
    ['email' => 'existing@example.com'],
    ['name' => 'John']
);

// For raw queries with error handling
try {
    DB::insert('INSERT INTO users (email, name) VALUES (?, ?)',
        ['test@example.com', 'Test']);
} catch (QueryException $e) {
    if ($e->errorInfo[1] == 1062) {
        // Duplicate entry
        return response()->json(['error' => 'Email already exists'], 422);
    }
    throw $e;
}

Error Information

Language

php

Framework

laravel

Difficulty

Intermediate

Views

318

Related Errors

403 Laravel

AuthorizationException (403)

The authenticated user lacks permission to perform the requested action.
Database

Lock Wait Timeout Exceeded

A database query waited too long for a lock held by another transaction.
PHP

Type Error: Return Type Must Be Compatible

A method override has a return type that conflicts with the parent class or interface.
401 Laravel

AuthenticationException (401)

The user is not authenticated and cannot access the requested resource.
All tools