Add primary and foreign keys separately

Primary key will serve as autoincremented rowid while foreign key to
link to a snapshot or snapshot_port. Also, add cascade delete so that
on deleting a snapshot, corresponding information is also removed.

src/cregistry/entry.c

@@ -1387,7 +1387,7 @@ int snapshot_store_ports(reg_registry* reg, reg_entry* entry, reg_error* errPtr)
             sqlite3_stmt* stmt = NULL;
             if(reg_entry_propget(entries[i], key1, &port_name, &error)
                 && reg_entry_propget(entries[i], key2, &requested, &error)){
-                char* query = "INSERT INTO registry.snapshot_ports (id, port_name, requested) "
+                char* query = "INSERT INTO registry.snapshot_ports (snapshots_id, port_name, requested) "
                     "VALUES (?, ?, ?)";
                 // entry->id is snapshot's id
                 if ((sqlite3_prepare_v2(reg->db, query, -1, &stmt, NULL) == SQLITE_OK)

src/cregistry/sql.c

@@ -207,20 +207,24 @@ int create_tables(sqlite3* db, reg_error* errPtr) {
         /* snapshot ports table */
         /* a complete copy of all the installed ports for a snapshot */
         "CREATE TABLE registry.snapshot_ports ("
-              "id INTEGER"
+              "id INTEGER PRIMARY KEY"
+            ", snapshots_id INTEGER"
             ", port_name TEXT COLLATE NOCASE"
             ", requested INTEGER"
-            ", FOREIGN KEY(id) REFERENCES snapshots(id))",
+            ", FOREIGN KEY(snapshots_id) REFERENCES snapshots(id))"
+            " ON DELETE CASCADE",
         "CREATE INDEX registry.snapshot_port ON snapshot_ports"
             "(id, port_name)",
 
         /* snapshot port variants table */
         /* all variants (+, -) of the ports in a snapshot */
         "CREATE TABLE registry.snapshot_port_variants ("
-              "id INTEGER"
+              "id INTEGER PRIMARY KEY"
+            ", snapshot_ports_id INTEGER"
             ", variant_name TEXT COLLATE NOCASE"
             ", variant_sign TEXT"
-            ", FOREIGN KEY(id) REFERENCES snapshot_ports(id))",
+            ", FOREIGN KEY(snapshot_ports_id) REFERENCES snapshot_ports(id))"
+            " ON DELETE CASCADE",
         "CREATE INDEX registry.snapshot_port_variant ON snapshot_port_variants(id)",
 
         "COMMIT",
@@ -745,26 +749,30 @@ int update_db(sqlite3* db, reg_error* errPtr) {
                 /* snapshots table */
                 "CREATE TABLE registry.snapshots ("
                       "id INTEGER PRIMARY KEY"
-                    ", created_at DATETIME"
+                    ", created_at DATETIME DEFAULT CURRENT_TIMESTAMP NOT NULL"
                     ", note TEXT"
                     ")",
 
                 /* snapshot ports table */
                 "CREATE TABLE registry.snapshot_ports ("
-                      "id INTEGER"
+                      "id INTEGER PRIMARY KEY"
+                    ", snapshots_id INTEGER"
                     ", port_name TEXT COLLATE NOCASE"
                     ", requested INTEGER"
-                    ", FOREIGN KEY(id) REFERENCES snapshots(id))",
+                    ", FOREIGN KEY(snapshots_id) REFERENCES snapshots(id))"
+                    " ON DELETE CASCADE",
 
                 "CREATE INDEX registry.snapshot_port ON snapshot_ports"
                     "(id, port_name)",
 
                 /* snapshot port variants table */
                 "CREATE TABLE registry.snapshot_port_variants ("
-                      "id INTEGER"
+                      "id INTEGER PRIMARY KEY"
+                    ", snapshot_ports_id INTEGER"
                     ", variant_name TEXT COLLATE NOCASE"
                     ", variant_sign TEXT"
-                    ", FOREIGN KEY(id) REFERENCES snapshot_ports(id))",
+                    ", FOREIGN KEY(snapshot_ports_id) REFERENCES snapshot_ports(id))"
+                    " ON DELETE CASCADE",
 
                 "CREATE INDEX registry.snapshot_port_variant ON snapshot_port_variants(id)",