---
id: clickhouse
title: ClickHouse
---
# ClickHouse
ToolJet can connect to the ClickHouse to read and write data.
:::info
ToolJet uses this [NodeJS](https://github.com/TimonKK/clickhouse) 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](/docs/data-sources/overview)** 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
After setting up the ClickHouse data source, you can click on the `+` button of the query manager and select the ClickHouse data source that you added in the previous step to create a new query.
:::info
For more details on clickhouse visit [Clickhouse docs](https://clickhouse.com/docs/en/quick-start).
:::
## Supported Operations:
- [SQL Query](#sql-query)
- [Insert array of objects](#supported-operations)
### SQL Query
Use this to operation to enter **[ClickHouse SQL Statements](https://clickhouse.com/docs/en/sql-reference/statements/)**. These statements represent various kinds of action you can perform using SQL queries.
#### Example SQL queries
- **SELECT**:
```sql
SELECT * from test array;
```
- **CREATE**:
```sql
CREATE TABLE test array3 (
date Date,
str String,
arr Array(String),
arr2 Array (Date)
arr3 Array(UInt32) ,
id1 UUID
)ENGINE=MergeTree () ORDER BY(str)
```
- **ALTER TABLE**(add column)
```sql
ALTER TABLE test array1 ADD COLUMN Added2 UInt32;
```
- **SELECT WITH WHERE CLAUSE**
```sql
SELECT * FROM test array1 WHERE str='Somethingl...'
```
- **UPDATE**
```sql
ALTER TABLE test_array1 UPDATE arr = (12] WHERE str='Somethingl...'
```
- **DELETE**
```sql
ALTER TABLE test_array1 DELETE WHERE str= 'Somethingl...'
```
- **NORMAL INSERT**
1. Step 1 - Creating Table
```sql
CREATE TABLE test array4 (
name String,
date Date
)ENGINE=MergeTree () ORDER BY (name)
```
2. Step 2 - Insert
```sql
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**
- **Fields**
- **Table name**
**Example Body value:**
```javascript
[
{
date: "2018-01-01",
str: "Something1...",
arr: [],
arr2: ["1985-01-02", "1985-01-03"],
arr3: [1, 2, 3, 4, 5],
id1: "102a05cb-8aaf-4f11-a442-20c3558e4384",
},
{
date: "2018-02-01",
str: "Something2...",
arr: ["5670000000", "Something3..."],
arr2: ["1985-02-02"],
arr3: [],
id1: "c2103985-9a1e-4f4a-b288-b292b5209de1",
},
];
```
