Network measurement is critical in network management such as performance monitoring, diagnosis, and traffic engineering. However, conventional network measurement solutions are limited by simple and fixed functionalities as well as coarse-grained statistics which often fail to precisely illustrate network conditions. In this paper, we propose an event-driven declarative query language, EQuery, for programmable network management in order to design sophisticated measurement tasks and enable event mechanism to avoid human intervene. Furthermore, we design a compiler to support the query language on the EQuery Controller, which drives the chaining query workflow with nondeterministic finite automaton (NFA), and translates measurement jobs into low-level rules/states on the physical devices. Finally, we evaluate the effectiveness of our EQuery framework on a nation-wide operational network with real-time network statistics.