Feature/ddl migration (#1111)

* REFACTOR: use functions from ddl-help

* NEW: Default values are written to DDL

* fix testcase for sqlserver as default constraints will get names in future

* Reading DbMigration

* ADD: DbmIgrationGenerateTest

* Tables must be created first

* Sanity checks and some getters

* DdlMigration gets applied now

* ADD: Testcase and reference migration scripts

* no effective code changes: add comments

src/test/resources/dbmigration/migrationtest/postgres/1.3.sql

@@ -0,0 +1,30 @@
+-- apply changes
+create table migtest_e_ref (
+  id                            serial not null,
+  constraint pk_migtest_e_ref primary key (id)
+);
+
+alter table migtest_e_basic drop constraint ck_migtest_e_basic_status;
+alter table migtest_e_basic alter column status drop default;
+alter table migtest_e_basic alter column status drop not null;
+alter table migtest_e_basic add constraint ck_migtest_e_basic_status check ( status in ('N','A','I'));
+alter table migtest_e_basic drop constraint uq_migtest_e_basic_description;
+alter table migtest_e_basic alter column some_date drop default;
+alter table migtest_e_basic alter column some_date drop not null;
+
+update migtest_e_basic set user_id = 23 where user_id is null;
+alter table if exists migtest_e_basic drop constraint if exists fk_migtest_e_basic_user_id;
+alter table migtest_e_basic alter column user_id set default 23;
+alter table migtest_e_basic alter column user_id set not null;
+alter table migtest_e_basic add column old_boolean boolean not null default false;
+alter table migtest_e_basic add column old_boolean2 boolean;
+alter table migtest_e_basic add column eref_id integer;
+
+comment on column migtest_e_history.test_string is 'DROP COMMENT';
+create index ix_migtest_e_basic_indextest1 on migtest_e_basic (indextest1);
+create index ix_migtest_e_basic_indextest5 on migtest_e_basic (indextest5);
+drop index if exists ix_migtest_e_basic_indextest3;
+drop index if exists ix_migtest_e_basic_indextest6;
+alter table migtest_e_basic add constraint fk_migtest_e_basic_eref_id foreign key (eref_id) references migtest_e_ref (id) on delete restrict on update restrict;
+create index ix_migtest_e_basic_eref_id on migtest_e_basic (eref_id);
+