PromptHub
Back to Errors
Laravel Intermediate 27 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

27

Related Errors

Database

PDOException (Database Connection)

PHP failed to connect to or communicate with the database server.
403 Laravel

AuthorizationException (403)

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

Laravel Schedule Task Failure

A scheduled task failed to execute or completed with errors.
Database

Duplicate Entry

The code tries to insert a record with a value that already exists in a unique column.