Systems and methods for querying a database

A method implemented on a computing device for providing database query service to a user, the computing device including a memory and one or more processors, the method comprising:

• obtaining, by the one or more processors, a query request to query a database, wherein the database includes a plurality of data tables;
• determining, by the one or more processors, one or more target data tables among the plurality of data tables based on the query request;
• generating, by the one or more processors, 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, wherein:
• the plurality of data tables include a first data table and a second data table that have a common field and a segment with a direct in between the first data table and the second data table,
• if the first data table is a target data table, the segment between the first data table and the second data table has a direction from the first data table to the second data table and a first weight, and
• if the first data table is not a target data table, the segment between the first data table and the second data table has a direction from the first data table to the second data table and a second weight that is larger than the first weight;
• determining, by the one or more processors, a reference data table among the one or more target data tables;
• for each of the one or more target data tables,
• traversing, by the one or more processors, the directed graph to determine a target path with a shortest distance between the reference data table and a target data table;
• and
• querying, by the one or more processors, the database based on one or more target paths with the shortest distances.

A non-transitory computer readable medium embodying a computer program product, the computer program product comprising instructions configured to cause a computing device to:

• obtain a query request to query a database, wherein the database includes a plurality of data tables;
• determine one or more target data tables among the plurality of data tables based on the query request;
• generate 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, wherein:
• the plurality of data tables include a first data table and a second data table that have a common field and a segment with a direct in between the first data table and the second data table,
• if the first data table is a target data table, the segment between the first data table and the second data table has a direction from the first data table to the second data table and a first weight, and
• if the first data table is not a target data table, the segment between the first data table and the second data table has a direction from the first data table to the second data table and a second weight that is larger than the first weight;
• determine a reference data table among the one or more target data tables;
• for each of the one or more target data tables,
• traverse the directed graph to determine a target path with a shortest distance between the reference data table and a target data table;
• and,
• query the database based on one or more target paths with the shortest distances.