--- a/python/storage.py	Wed Jul 22 14:18:06 2015 -0400
+++ b/python/storage.py	Sat Jul 25 22:36:39 2015 -0400
@@ -34,6 +34,50 @@
     except sqlite3.OperationalError as error:
         printDBError(error)
 
+def createIndex(connection, tableName, columnName, unique = False):
+    '''Creates an index for the column in the table
+    I will make querying with a condition on this column faster'''
+    try:
+        #connection = sqlite3.connect(filename)
+        cursor = connection.cursor()
+        s = "CREATE "
+        if unique:
+            s += "UNIQUE "
+        cursor.execute(s+"INDEX IF NOT EXISTS "+tableName+"_"+columnName+"_index ON "+tableName+"("+columnName+")")
+        connection.commit()
+        #connection.close()
+    except sqlite3.OperationalError as error:
+        printDBError(error)
+
+def getNumberRowsTable(connection, tableName, columnName = None):
+    '''Returns the number of rows for the table
+    If columnName is not None, means we want the number of distinct values for that column
+    (otherwise, we can just count(*))'''
+    try:
+        cursor = connection.cursor()
+        if columnName is None:
+            cursor.execute("SELECT COUNT(*) from "+tableName)
+        else:
+            cursor.execute("SELECT COUNT(DISTINCT "+columnName+") from "+tableName)
+        return cursor.fetchone()[0]
+    except sqlite3.OperationalError as error:
+        printDBError(error)
+
+def getMinMax(connection, tableName, columnName, minmax):
+    '''Returns max/min or both for given column in table
+    minmax must be string max, min or minmax'''
+    try:
+        cursor = connection.cursor()
+        if minmax == 'min' or minmax == 'max':
+            cursor.execute("SELECT "+minmax+"("+columnName+") from "+tableName)
+        elif minmax == 'minmax':
+            cursor.execute("SELECT MIN("+columnName+"), MAX("+columnName+") from "+tableName)
+        else:
+            print("Argument minmax unknown: {}".format(minmax))
+        return cursor.fetchone()[0]
+    except sqlite3.OperationalError as error:
+        printDBError(error)
+
 # TODO: add test if database connection is open
 # IO to sqlite
 def writeTrajectoriesToSqlite(objects, outputFilename, trajectoryType, objectNumbers = -1):
@@ -322,7 +366,7 @@
             queryStatement = 'SELECT OF.object_id, P.frame_number, avg(P.x_coordinate), avg(P.y_coordinate) from '+tableName+' P, objects_features OF where P.trajectory_id = OF.trajectory_id'
             if objectNumbers is not None:
                 queryStatement += ' and OF.object_id '+objectCriteria
-            queryStatement += ' group by OF.object_id, P.frame_number ORDER BY OF.object_id, P.frame_number'
+            queryStatement += ' GROUP BY OF.object_id, P.frame_number ORDER BY OF.object_id, P.frame_number'
             cursor.execute(queryStatement)
             logging.debug(queryStatement)
         elif trajectoryType in ['bbtop', 'bbbottom']:
@@ -332,7 +376,7 @@
                 corner = 'bottom_right'
             queryStatement = 'SELECT object_id, frame_number, x_'+corner+', y_'+corner+' FROM '+tableName
             if objectNumbers is not None:
-                queryStatement += ' where object_id '+objectCriteria
+                queryStatement += ' WHERE object_id '+objectCriteria
             queryStatement += ' ORDER BY object_id, frame_number'
             cursor.execute(queryStatement)
             logging.debug(queryStatement)