[DMDB] Notes on query processing, better summary for those, some exam notes

semester4/dmdb/code/sql/ddl/create.sql

@@ -1,6 +1,7 @@
 CREATE TABLE TableName (
-    Attribute integer,
-    OtherAttribute varchar (30),
-    NextAttribute character (2) default "AP", -- default value, if unset on insert
-    PRIMARY KEY (Attribute) -- primary key, as in RA
+    Attribute integer UNIQUE,
+    OtherAttribute varchar(30) NOT NULL, -- Not null
+    NextAttribute character(2) default "AP", -- default value, if unset on insert
+    PRIMARY KEY (Attribute), -- primary key, as in RA
+    CHECK (Attribute > 1)
 );