[12.x] Add check constraints support for database schema

[ismayil-dev]

Add Database Check Constraints Support

Overview

This PR adds native support for database check constraints to Laravel's Schema Builder, bringing a long-requested feature that enhances data integrity at the database level.

Check constraints allow you to enforce business rules directly in the database, ensuring data consistency regardless of how data is inserted or updated. This is particularly valuable for multi-application environments or when data integrity is critical.

Usage

Schema::create('orders', function (Blueprint $table) {
    $table->id();
    $table->string('status');
    $table->decimal('amount', 10, 2);
    
    $table->checkConstraint('valid_status', function (CheckConstraintBuilder $constraint) {
        $constraint->whereIn('status', ['pending', 'shipped', 'delivered']);
    });
    
    $table->checkConstraint('positive_amount', function (CheckConstraintBuilder $constraint) {
        $constraint->rule('amount', '>', 0);
    });
    
    $table->checkConstraint('shipping_logic', function (CheckConstraintBuilder $constraint) {
        $constraint->where('status', '=', 'shipped', function ($q) {
            $q->rule('shipped_at', 'IS NOT NULL');
        })->orWhere('status', '!=', 'shipped', function ($q) {
            $q->rule('shipped_at', 'IS NULL');
        });
    });
});

// Add to existing tables
Schema::table('users', function (Blueprint $table) {
    $table->checkConstraint('valid_age', function (CheckConstraintBuilder $constraint) {
        $constraint->rule('age', '>=', 18);
    });
});

// Drop constraints
Schema::table('users', function (Blueprint $table) {
    $table->dropConstraint('valid_age');
});

Database Support

Database	Create	Add/Drop	Version
MySQL	✅	✅	>= 8.0.16
MariaDB	✅	✅	>= 10.2.1
PostgreSQL	✅	✅	All
SQL Server	✅	✅	All
SQLite	✅	❌*	All

*SQLite limitations handled with clear exceptions

Features

• Fluent API with where(), orWhere(), whereIn(), whereNotIn()
• Support for all comparison operators and NULL checks
• Complex nested conditions
• Full test coverage across all databases
• Zero breaking changes

Implementation Highlights

• Consistent API: Follows Laravel's established patterns for schema building
• Proper Grammar Abstraction: Each database driver handles constraints appropriately
• Comprehensive Testing: Full test coverage across all supported databases
• Version Awareness: Uses @RequiresDatabase attributes to ensure compatibility
• Error Handling: Clear exceptions for unsupported operations (e.g., SQLite limitations)

Testing Note

The current test suite covers the main functionality across all databases. If this feature direction is approved, I can add more comprehensive grammar-specific tests and additional edge case coverage as needed.

[github-actions]

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[taylorotwell]

Thanks for your pull request to Laravel!

Unfortunately, I'm going to delay merging this code for now. To preserve our ability to adequately maintain the framework, we need to be very careful regarding the amount of code we include.

If applicable, please consider releasing your code as a package so that the community can still take advantage of your contributions!

[hafezdivandari]

#56929