修改了ER图和DDL语言

code/database/ddl.sql

@@ -51,18 +51,12 @@ create table T_Type(
     d_id        varchar(5),
     n_id        varchar(5),
     price       numeric(5,2),
+    producer    varchar(5),
     
-    primary key (d_id),
+    primary key (d_id,n_id),
     foreign key (d_id) references T_Drugs(ID),
-    foreign key (n_id) references T_Norms(ID));
-    
-create table T_Produce(
-    d_id    varchar(5),
-    v_id    varchar(5),
-    
-    primary key (d_id,v_id),
-    foreign key (d_id) references T_Drugs(ID),
-    foreign key (v_id) references T_Vendor(ID));
+    foreign key (n_id) references T_Norms(ID),
+    foreign key (producer) references T_Vendor(ID));
     
 create table T_Require(
     d_id    varchar(5),