【ClickHouse】2：clickhouse基本语法

背景介绍：

有三台CentOS7服务器安装了ClickHouse

HostName	IP	安装程序	程序端口
centf8118.sharding1.db	192.168.81.18	clickhouse-server，clickhouse-client	9000
centf8119.sharding2.db	192.168.81.19	clickhouse-server，clickhouse-client	9000
centf8120.sharding3.db	192.168.81.20	clickhouse-server，clickhouse-client	9000

一：登录数据库

本地登录：clickhouse-client

[root@centf8118 format_schemas]# clickhouse-client
ClickHouse client version 20.6.4.44 (official build).
Connecting to localhost:9000 as user default.
Connected to ClickHouse server version 20.6.4 revision 54436.

centf8118.sharding1.db :) show databases;

SHOW DATABASES

┌─name───────────────────────────┐
│ _temporary_and_external_tables │
│ default                        │
│ system                         │
│ testdb                         │
└────────────────────────────────┘

4 rows in set. Elapsed: 0.003 sec. 

centf8118.sharding1.db :) select now();

SELECT now()

┌───────────────now()─┐
│ 2020-08-26 15:11:22 │
└─────────────────────┘

1 rows in set. Elapsed: 0.010 sec. 

centf8118.sharding1.db :)

　　

远程登录：(用本机clickhouse-client连接远程clickhouse-server服务器)

clickhouse-client --host 192.168.81.20 --port 9000 --database default --user default --password ""

如果登录不上，telnet一下端口，看通不通。

telnet ping 192.168.81.20 9000

[root@centf8118 ~]# telnet 192.168.81.20 9000
Trying 192.168.81.20 ...
telnet: connect to address 192.168.81.20: Connection refused

如果telent不同，查看iptables有没有添加端口。（三台机器都添加，我这里是添加的都是IP和端口区间，按实际需求配置。）

-A INPUT -p tcp -m iprange --src-range 192.168.81.18-192.168.81.20 -m tcp --dport 9000:9200 -j ACCEPT

如果iptables都配置了9000端口还是不通。查看监听端口：

[root@centf8118 ~]# netstat -anltp|grep :9000
tcp        0      0 127.0.0.1:9000          0.0.0.0:*               LISTEN      22710/clickhouse-se 

如果是127.0.0.1:9000需要修改配置，放开远程访问。

vim /etc/clickhouse-server/config.xml

修改配置文件中的注释掉的<listen_host>0.0.0.0</listen_host>放出来。

修改配置后重启服务： server clickhouse-server restart

再次查看监听端口：

[root@centf8118 ~]# netstat -anltp|grep :9000
tcp        0      0 0.0.0.0:9000            0.0.0.0:*               LISTEN      6060/clickhouse-ser

　　

再尝试登录数据库：(安装后系统默认会创建一个登录账号default，密码为空字符串）

[root@centf8118 ~]# clickhouse-client --host 192.168.81.20 --port 9000 --database default --user default --password ""
ClickHouse client version 20.6.4.44 (official build).
Connecting to database default at 192.168.81.20:9000 as user default.
Connected to ClickHouse server version 20.6.4 revision 54436.

centf8120.sharding3.db :) show databases;

SHOW DATABASES

┌─name───────────────────────────┐
│ _temporary_and_external_tables │
│ default                        │
│ system                         │
│ testdb                         │
│ tutorial                       │
└────────────────────────────────┘

5 rows in set. Elapsed: 0.004 sec. 

centf8120.sharding3.db :)

　　

客户端登录，默认是一行一段完整的SQL，如果是多行的sql，就会一行行执行并报错。

clickhouse-client -m 可以支持多行SQL；

二：角色账号相关操作

官方文档：https://clickhouse.tech/docs/en/sql-reference/statements/create/role/

# 创建角色，账号

CREATE ROLE [IF NOT EXISTS | OR REPLACE] name
    [SETTINGS variable [= value] [MIN [=] min_value] [MAX [=] max_value] [READONLY|WRITABLE] | PROFILE 'profile_name'] [,...]

CREATE USER [IF NOT EXISTS | OR REPLACE] name [ON CLUSTER cluster_name]
    [IDENTIFIED [WITH {NO_PASSWORD|PLAINTEXT_PASSWORD|SHA256_PASSWORD|SHA256_HASH|DOUBLE_SHA1_PASSWORD|DOUBLE_SHA1_HASH}] BY {'password'|'hash'}]
    [HOST {LOCAL | NAME 'name' | REGEXP 'name_regexp' | IP 'address' | LIKE 'pattern'} [,...] | ANY | NONE]
    [DEFAULT ROLE role [,...]]
    [SETTINGS variable [= value] [MIN [=] min_value] [MAX [=] max_value] [READONLY|WRITABLE] | PROFILE 'profile_name'] [,...]

　　

Examples：

# 创建角色并赋予权限
CREATE ROLE accountant;
GRANT SELECT ON db.* TO accountant;

# 给用户添加角色
GRANT accountant TO mira;

# 修改角色
SET ROLE accountant;
SELECT * FROM db.*;

　　

CREATE USER mira HOST IP '127.0.0.1' IDENTIFIED WITH sha256_password BY 'qwerty'

CREATE USER john DEFAULT ROLE role1, role2

ALTER USER user DEFAULT ROLE ALL

ALTER USER john DEFAULT ROLE ALL EXCEPT role1, role2

　　

# 查询角色，账号

# 修改角色，账号

ALTER ROLE [IF EXISTS] name [ON CLUSTER cluster_name]
    [RENAME TO new_name]
    [SETTINGS variable [= value] [MIN [=] min_value] [MAX [=] max_value] [READONLY|WRITABLE] | PROFILE 'profile_name'] [,...]

　　

ALTER USER [IF EXISTS] name [ON CLUSTER cluster_name]
    [RENAME TO new_name]
    [IDENTIFIED [WITH {PLAINTEXT_PASSWORD|SHA256_PASSWORD|DOUBLE_SHA1_PASSWORD}] BY {'password'|'hash'}]
    [[ADD|DROP] HOST {LOCAL | NAME 'name' | REGEXP 'name_regexp' | IP 'address' | LIKE 'pattern'} [,...] | ANY | NONE]
    [DEFAULT ROLE role [,...] | ALL | ALL EXCEPT role [,...] ]
    [SETTINGS variable [= value] [MIN [=] min_value] [MAX [=] max_value] [READONLY|WRITABLE] | PROFILE 'profile_name'] [,...]

　　

# 删除角色，账号

DROP ROLE [IF EXISTS] name [,...] [ON CLUSTER cluster_name]

DROP USER [IF EXISTS] name [,...] [ON CLUSTER cluster_name]

　　

三：数据库相关操作

官方文档：https://clickhouse.tech/docs/en/sql-reference/statements/create/database/

# 创建数据库

CREATE DATABASE [IF NOT EXISTS] db_name [ON CLUSTER cluster] [ENGINE = engine(...)]

　

# 查询数据库

SHOW DATABASES [INTO OUTFILE filename] [FORMAT format]

　　

# 删除数据库

DROP DATABASE [IF EXISTS] db [ON CLUSTER cluster]

　　

四：表相关操作

# 创建表

# 新创建表
CREATE TABLE [IF NOT EXISTS] [db.]table_name [ON CLUSTER cluster]
(
    name1 [type1] [DEFAULT|MATERIALIZED|ALIAS expr1] [compression_codec] [TTL expr1],
    name2 [type2] [DEFAULT|MATERIALIZED|ALIAS expr2] [compression_codec] [TTL expr2],
    ...
) ENGINE = engine

　　

# 拷贝已存在的表结构
CREATE TABLE [IF NOT EXISTS] [db.]table_name AS [db2.]name2 [ENGINE = engine]

　　

# 查询表

SHOW [TEMPORARY] TABLES [{FROM | IN} <db>] [LIKE '<pattern>' | WHERE expr] [LIMIT <N>] [INTO OUTFILE <filename>] [FORMAT <format>]

　　

SELECT name FROM system.tables WHERE database = <db> [AND name LIKE <pattern>] [LIMIT <N>] [INTO OUTFILE <filename>] [FORMAT <format>]

　　

# 删除表

DROP [TEMPORARY] TABLE [IF EXISTS] [db.]name [ON CLUSTER cluster]