Using Clickhouse Commands

Updated on 2024-04-29 GMT+08:00

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

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

Create a database.
```
create database demo;
```
Use the database.
```
use demo;
```
Check the database in use.
```
select currentDatabase();
```

Create a table.

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

View the table structure.
```
desc demo_t;
```

Insert data.

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

View the table.
```
select * from demo_t;
```
View the database and table.
- Viewing the database
```
show databases;
```
- Viewing the table
```
show tables;
```
Delete the database and table.
- Deleting the table
```
drop table demo_t;
```
  NOTE:
  - 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;
```

Parent topic: Using ClickHouse

Previous topic: Using a Client to Access a ClickHouse Cluster

Next topic: Migrating ClickHouse Data

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