Data quality assessments (DQA) reveal quality problems in electronic medical records (EHR) data. Generally, DQA methods describe quality rules in programming languages through hard-coding, which limits the implementation of DQA between heterogeneous systems and the interoperability of quality rules. To cover this gap, we conducted a case study applying Guideline Definition Language (GDL) in DQA to assess the quality of patient admission data in an EHR system of a hospital in China.