check the result is not nil

core/hack/version.go

@@ -1,6 +1,6 @@
 package hack
 
 const (
-	Version = "2017-03-05 11:28:16 +0800 @9e216ed"
-	Compile = "2017-04-02 07:55:14 +0800 by go version go1.8 darwin/amd64"
+	Version = "2017-04-25 19:26:47 +0800 @8b29b42"
+	Compile = "2017-05-03 19:55:36 +0800 by go version go1.8 darwin/amd64"
 )

proxy/server/conn_select.go

@@ -710,12 +710,14 @@ func (c *ClientConn) calFuncExprValue(funcName string,
 			return nil, nil
 		}
 		for _, r := range rs {
-			for k := range r.Values {
-				result, err := r.GetInt(k, index)
-				if err != nil {
-					return nil, err
+			if r != nil {
+				for k := range r.Values {
+					result, err := r.GetInt(k, index)
+					if err != nil {
+						return nil, err
+					}
+					num += result
 				}
-				num += result
 			}
 		}
 		return num, nil