[DMDB] SQL intro (DML, DDL)

semester4/dmdb/code/sql/ddl/alter.sql

@@ -0,0 +1,3 @@
+ALTER TABLE TableName ADD COLUMN (col integer);
+ALTER TABLE TableName ADD COLUMN (AnotherColumn integer default "");
+ALTER TABLE TableName DROP COLUMN AnotherColumn;

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

@@ -1,6 +1,6 @@
 CREATE TABLE TableName (
     Attribute integer,
     OtherAttribute varchar (30),
-    NextAttribute character (2) default "AP",
-    PRIMARY KEY (Attribute)
+    NextAttribute character (2) default "AP", -- default value, if unset on insert
+    PRIMARY KEY (Attribute) -- primary key, as in RA
 );

semester4/dmdb/code/sql/ddl/delete.sql

@@ -0,0 +1 @@
+DROP TABLE TableName;