Allow setting a default for a column that already has a default on Mi…

…crosoft SQL Server

Microsoft SQL Server complains because it treates defaults as
constraints and requires you to drop a constraint before adding
one.

We already had code to drop the constraint, but it was only used
for drop_column, not for set_column default previously.

CHANGELOG

@@ -1,5 +1,7 @@
 === master
 
+* Allow setting a default for a column that already has a default on Microsoft SQL Server (jeremyevans)
+
 * Fix keyword argument separation warnings on Ruby master branch in csv_serializer plugin (jeremyevans)
 
 * Add association_multi_add_remove plugin for adding/removing multiple associated objects in a single method call (AlexWayfer, jeremyevans) (#1641)

lib/sequel/adapters/shared/mssql.rb

@@ -290,7 +290,9 @@ def alter_table_sql(table, op)
  end
  "ALTER TABLE #{quote_schema_table(table)} ALTER COLUMN #{quote_identifier(op[:name])} #{type_literal(:type=>type)} #{'NOT ' unless op[:null]}NULL"
  when :set_column_default
- "ALTER TABLE #{quote_schema_table(table)} ADD CONSTRAINT #{quote_identifier("sequel_#{table}_#{op[:name]}_def")} DEFAULT #{literal(op[:default])} FOR #{quote_identifier(op[:name])}"
+ sqls = []
+ add_drop_default_constraint_sql(sqls, table, op[:name])
+ sqls << "ALTER TABLE #{quote_schema_table(table)} ADD CONSTRAINT #{quote_identifier("sequel_#{table}_#{op[:name]}_def")} DEFAULT #{literal(op[:default])} FOR #{quote_identifier(op[:name])}"
  else
  super(table, op)
  end

spec/integration/schema_test.rb

@@ -634,6 +634,15 @@
  @ds.all.must_equal [{:id=>10}, {:id=>20}]
  end
 
+ it "should set column defaults correctly if column has existing default" do
+ @db.create_table!(:items){Integer :id, :default=>10}
+ @ds.insert
+ @ds.all.must_equal [{:id=>10}]
+ @db.alter_table(:items){set_column_default :id, 20}
+ @ds.insert
+ @ds.all.must_equal [{:id=>10}, {:id=>20}]
+ end
+
  it "should set column defaults to nil correctly" do
  @db.create_table!(:items){Integer :id}
  @ds.insert(:id=>10)