[6.x] Fix laravel migrations when migrating to sql server (dropColumn with default value)

[joelharkes]

Currently when running the following script would work in mysql (and mariadb) but would fail in sqlserver.

Schema::create('foo', function($table)
{
     $table->boolean('bar')->default(false);
});
Schema::table('foo', function($table)
{
    $table->dropColumn('bar'); // Don't works!
});

this would throw error: [Illuminate\Database\QueryException] SQLSTATE[42000]: [Microsoft][SQL Server Native Client 11.0][SQL Server]The object 'DF__foo__bar__322242A7' is dependent on column 'bar'. (SQL: alter table "foo" drop column "bar")

The problem: on dropColumn() your fluent code doesn't know if the column had a default constraint. This code added would retrieve wether a default constraint exists on dropped columns and remove them before dropping the column as well, and thus not triggering a is dependent on column constraint QueryException.

This solution

Creates a script before drop column is called to get the Default Constraints and drop these before the column is dropped.

In this case it would run script:

DECLARE @sql NVARCHAR(MAX) = '';
SELECT @sql += 'ALTER TABLE [dbo].[foo] DROP CONSTRAINT ' + OBJECT_NAME([default_object_id]) + ';' "
FROM SYS.COLUMNS
WHERE [object_id] = OBJECT_ID('[dbo].[foo') AND [name] in ('bar');
EXEC(@sql)

Which creates the following sql and executes it:

ALTER TABLE [dbo].[foo] DROP CONSTRAINT DF__foo__bar__322242A7;

Before running sql

alter table foo drop column bar

End result

migrating from mysql to sqlserver becomes almost seamless, no need to specify dropping default constraints manually like proposed in other issues like: #4402

Tests

I couldn't create e2e tests because this laravel travis setup has no sql server?
But locally this fix has worked great for me.

[yaroslavmo]

I faced the same issue today. Really hope they will merge your fix!

[cirolosapio]

I have the same problem.
With a table under the dbo schema the problem is solved, but with a table under a custom schema (example schema.table) the query fails

[joelharkes]

I'll see to find time to make laravel tests for SQL server (which are currently missing) using the SQL server Development Docker image.

to test these cases, sorry for the inconvenience guys.

[joelharkes]

@heartbeatLV i'm testing this now can you please provide a small piece reproducable piece of code so i can unit test this?

[cirolosapio]

@heartbeatLV i'm testing this now can you please provide a small piece reproducable piece of code so i can unit test this?

public function up() {
    // check schema exists
    // SELECT * FROM sys.schemas WHERE name = 'example'
    DB::statement('CREATE SCHEMA example');

    Schema::create('example.tests', function (Blueprint $table) {
        $table->id();
        $table->string('name');
        $table->timestamps();
    });

    Schema::table('example.tests', function (Blueprint $table) {
        $table->boolean('testBool')->default(false);
    });

    Schema::table('example.tests', function (Blueprint $table) {
        $table->dropColumn('testBool');
    });
}

public function down() {
    // this will not work because the "existing" check fails
    // Schema::dropIfExists('example.tests');
    // SQL: if exists (select * from INFORMATION_SCHEMA.TABLES where TABLE_NAME = 'example.tests') drop table "example"."tests"

    // workaround
    DB::statement('DROP TABLE IF EXISTS example.tests');

    DB::statement('DROP SCHEMA IF EXISTS example');
}

hope it helps

[joelharkes]

Thanks this is perfect, im testing now. hope to finalize a PR coming week into laravel :)

[joelharkes]

@heartbeatLV it will be fixed in next version of laravel once my PR gets merged: #32957