Clickhouse learning (IV) SQL operation

increase

INSERT INTO  Database name . Table name  [(c1, c2, c3)] VALUES (v11, v12, v13), (v21, v22, v23), ...

insert into t_order_mt values
(101,'sku_001',1000.00,'2021-08-01 12:00:00'),
(101,'sku_002',2000.00,'2021-08-01 12:00:00');

Delete

although clickhouse It provides the function of deletion and modification, but its principle still needs to be consistent with alter Syntax combined and transaction not supported .

Delete an element in the table

ALTER TABLE [ Database name .] Table name  delete where  Field  = ' Property value ';

alter table t_order_smt delete where sku_id ='sku_001';

Delete a column in the table

ALTER TABLE  Table name  DROP COLUMN [IF EXISTS]  Field name 

alter table t_order_mt drop column total_amount;

Delete table

DROP TABLE  Table name 

drop table t_order_mt;

Change

Add a row

ALTER TABLE  Table name  ADD COLUMN  Name   Field type  AFTER  Existing columns 

alter table t_order_rmt add column test String after sku_id;

Add notes

ALTER TABLE  Table name  COMMENT  Field name  'xxxxxxxxxx'

alter table t_order_rmt comment column test ' Test add comments ';

Change the type of column

ALTER TABLE  Table name  MODIFY COLUNM  Field name   Field type 

alter table t_order_rmt modify column test int;

check

and mysql If it's basically the same, don't write , The specific official website is very detailed
https://clickhouse.tech/docs/zh/sql-reference/statements/select/
Be careful :

• It supports all kinds of join, however join The operation cannot use the cache , So even if it's the same twice join sentence ,clickhouse It will also be regarded as two new sql
• Custom functions are not supported
• The window function is also being tested

Data import

data

csv form

 cat test.csv | clickhouse-client --query="insert into im_test format CSV";

Custom splitters

cat test.csv | clickhouse-client --format_csv_delimiter="|" --query="INSERT INTO im_test FORMAT CSV";

Export data

 clickhouse-client --query "select * from im_test where age=23" --format CSVWithNames> /root/test2.csv