ToolJet/docs/versioned_docs/version-3.0.0-LTS/data-sources/clickhouse.md

id	title
clickhouse	ClickHouse

ToolJet can connect to the ClickHouse to read and write data.

:::info ToolJet uses this NodeJS client for ClickHouse. :::

Connection

To establish a connection with the Clickhouse data source, you can either click on the + Add new data source button located on the query panel or navigate to the Data Sources page through the ToolJet dashboard.

ToolJet requires the following to connect to your ClickHouse Database:

• Username
• Password
• Host
• Port
• Database Name
• Protocol
• Use Post
• Trim Query
• Use Gzip
• Debug
• Raw

Querying ClickHouse

1. Click on + Add button of the query manager at the bottom panel of the editor.
2. Select the ClickHouse datasource added in previous step.
3. Select the operation you want to perform and enter the query.
4. Click on the Preview button to preview the output or Click on the Run button to create and trigger the query.

:::info For more details on clickhouse visit Clickhouse Docs. :::

Supported Operations

• SQL Query
• Insert array of objects

SQL Query

Use this to operation to enter ClickHouse SQL Statements. These statements represent various kinds of action you can perform using SQL queries.

Example SQL queries

SELECT:

SELECT * from test array;

<img className="screenshot-full" src="/img/datasource-reference/clickhouse/select-v2.png" alt="ClickHouse SQL Statement operation" style={{marginBottom:'15px'}}/>

CREATE:

CREATE TABLE test array3 (
	date Date,
	str String,
	arr Array(String),
	arr2 Array (Date)
	arr3 Array(UInt32) ,
	id1 UUID
)ENGINE=MergeTree () ORDER BY(str)

<img className="screenshot-full" src="/img/datasource-reference/clickhouse/create-v2.png" alt="ClickHouse SQL Statement operation" style={{marginBottom:'15px'}}/>

ALTER TABLE (add column)

ALTER TABLE test array1 ADD COLUMN Added2 UInt32;

<img className="screenshot-full" src="/img/datasource-reference/clickhouse/alter-v2.png" alt="ClickHouse SQL Statement operation" style={{marginBottom:'15px'}} />

SELECT WITH WHERE CLAUSE

SELECT * FROM test array1 WHERE str='Somethingl...'

<img className="screenshot-full" src="/img/datasource-reference/clickhouse/selectwithwhere-v2.png" alt="ClickHouse SQL Statement operation" style={{marginBottom:'15px'}} />

UPDATE

ALTER TABLE test_array1 UPDATE arr = (12] WHERE str='Somethingl...'

<img className="screenshot-full" src="/img/datasource-reference/clickhouse/update-v2.png" alt="ClickHouse SQL Statement operation" style={{marginBottom:'15px'}} />

DELETE

ALTER TABLE test_array1 DELETE WHERE str= 'Somethingl...'

<img className="screenshot-full" src="/img/datasource-reference/clickhouse/delete-v2.png" alt="ClickHouse SQL Statement operation" style={{marginBottom:'15px'}} />

NORMAL INSERT

Step 1 - Creating Table

CREATE TABLE test array4 (
	name String,
	date Date
)ENGINE=MergeTree () ORDER BY (name)

Step 2 - Insert

INSERT INTO test_array4 (*) VALUES ('juvane', '1996-01-13')

:::info Giving Primary Key

CREATE TABLE db.table_name
(
	name1 type1, name2 type2, ...,
	PRIMARY KEY(expr1[, expr2,...])]
)
ENGINE = engine;

OR 
	
CREATE TABLE db.table_name
(
	name1 type1, name2 type2, ...
)
ENGINE = engine
PRIMARY KEY(expr1[, expr2,...]);

:::

Insert Array of Objects

Use this operation for inserting array of objects.

Required Parameters:

• Body
• Table name
• Fields

Example Body value:

[
  { "id": 1, "name": "Alice", "age": 25 },
  { "id": 2, "name": "Bob", "age": 30 },
  { "id": 3, "name": "Charlie", "age": 28 }
]