The present disclosure provides systems and methods for providing database query service to a user. The method may comprise: obtaining, a query request to query a database, wherein the database includes a plurality of data tables; determining one or more target data tables among the plurality of data tables based on the service request; generating a directed graph based on the plurality of data tables, wherein the directed graph includes one or more segment, each of which links two data tables; determining a reference data table among the one or more target data tables; for each of the one or more target data tables, traversing the directed graph to determine a target path with the shortest distance between the reference data table and a target data table; and, querying the database based on one or more target paths with the shortest paths.