How to achieve database sharding and table partitioning in MySQL for efficient querying.

To perform queries on MySQL sharding and partitioning, the following steps need to be followed:

1. Determine the sharding strategy: Based on actual requirements, establish the rules for sharding, such as sharding by user ID for databases and by order ID for tables.
2. Create sharding: Create the corresponding databases and tables based on the sharding rules.
3. Perform a query operation: Construct the appropriate SQL query statement based on the data needed for the query.
4. Database and table sharding routing: According to the sharding rules, queries are routed to the corresponding database and table.
5. Perform a query: Execute an SQL query statement to retrieve the query results.

Here is a simple example:

Assume there are two databases, referred to as db1 and db2, each containing two tables, labeled table1 and table2. The databases are sharded based on user ID, and the tables are sharded based on order ID.

1. Create sharding tables and databases.
2. Create database db1 with tables table1 and table2.
3. Create a db2 database that includes table1 and table2.
4. Construct the query:
   Assuming you want to query the order information of user ID 100 and the product information of order ID 200, you can construct the following query statement:
5. Fetch all records from table1 in database db1 where the user_id equals 100, and all records from table2 in database db2 where the order_id equals 200.
6. Database and table sharding routing:
   Determine which database and table the query should be routed to based on the table name in the query statement.
7. Execute the query:
   Run the above query statement to retrieve the query results.

Please note that in actual implementation, it may be necessary to use sharding middleware or frameworks to simplify the management and querying operations of sharding. The above example is only for demonstrating the basic process of sharding.