Refine curve to add type

script/sql/create/0.base.sql

@@ -2,6 +2,8 @@ create type _node_type as enum ('junction', 'reservoir', 'tank');
 
 create type _link_type as enum ('pipe', 'pump', 'valve');
 
+create type _curve_type as enum ('PUMP', 'EFFICIENCY', 'VOLUME', 'HEADLOSS');
+
 create table _node
 (
   id varchar(32) primary key
@@ -17,6 +19,7 @@ create table _link
 create table _curve
 (
   id varchar(32) primary key
+, type _curve_type not null
 );
 
 create table _pattern

script/sql/drop/0.base.sql

@@ -6,6 +6,8 @@ drop table if exists _link;
 
 drop table if exists _node;
 
+drop type if exists _curve_type;
+
 drop type if exists _link_type;
 
 drop type if exists _node_type;