add createTask(), getNextId()

DataStore.py

@@ -59,10 +59,36 @@ FROM projects
 SELECT id, name
 FROM tasks
 WHERE projectid = ?
-''' % (projectid,))
+''', (projectid,))
         tasks = {}
         for row in c:
             tasks[row[0]] = row[1]
         c.close()
         self.conn.commit()
         return tasks
+
+    def createTask(self, projectid, taskname):
+        c = self.conn.cursor()
+        tasks = self.getTasks(projectid)
+        if taskname in tasks.values():
+            return False
+        nextid = self.getNextId('tasks')
+        c.execute('''
+INSERT INTO tasks (id, projectid, name)
+VALUES (?, ?)
+''', (nextid, projectid, taskname))
+        c.close()
+        self.conn.commit()
+        return True
+
+    def getNextId(self, table):
+        c = self.conn.cursor()
+        nextid = 1
+        c.execute('''
+SELECT MAX(id)
+FROM %s
+''' % table)
+        for row in c:
+            nextid = row[0] + 1
+        c.close()
+        return nextid