Code MySQL:
SELECT t_request_detail.REQ_CO, t_request_detail.EU_NAME, m_model.MODEL_NA, t_request_detail.QTY_DEF, CONCAT(t_request_detail.SVC_Y, " years, ", t_request_detail.SVC_M, " months")
FROM t_request_detail 
 LEFT JOIN m_model ON t_request_detail.MODEL_CO = m_model.MODEL_CO
)

Can anyone explain why the use of CONCAT above causes an error?