Using Clickhouse Commands

This section describes common ClickHouse commands. After installing the ClickHouse client and loading environment variables, run the following commands to perform operations:

1. Connect to the ClickHouse cluster.
   Use the following command to connect to a normal cluster.

   ./clickhouse client --host Private IP address of the cluster   --port Port --user admin --password Password

   For details about the security cluster connection command. For details, see Connecting to a Security Cluster.

   ./clickhouse client --host Private IP address of the cluster --port port --user admin --password Password --secure --config-file /root/config.xml

2. Create a database.

   create database demo;

3. Use the database.

   use demo;

4. Check the database in use.

   select currentDatabase();

5. Create a table.

   create table demo_t(uid Int32,name String,age UInt32,gender String)engine = TinyLog;

6. View the table structure.

   desc demo_t;

7. Insert data.

   insert into demo_t values(1,'Candy','23','M'),(2,'cici','33','F');

8. View the table.

   select * from demo_t;

9. View the database and table.
   • Viewing the database

     show databases;

   • Viewing the table

     show tables;

10. Delete the database and table.
    • Deleting the table

      drop table demo_t;

      

      • Before deleting a data table, check whether the data table is in use to avoid unnecessary troubles.
      • After a data table is deleted, it can be restored within 24 hours. The restoration command is as follows:

        set allow_experimental_undrop_table_query = 1;

        UNDROP TABLE Data table name;

    • Deleting the database

      drop database demo;