> ## Documentation Index
> Fetch the complete documentation index at: https://mage-staging.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.
# SQL blocks
> Execute SQL commands directly in your database, data warehouse, etc.
## Credentials
Before starting, you need to add credentials so Mage can execute your SQL
commands.
Follow the steps for the database or data warehouse of your choice:
* [BigQuery](/integrations/databases/BigQuery#add-credentials)
* [Druid](/integrations/databases/Druid#add-credentials)
* [MySQL](/integrations/databases/MySQL#add-credentials)
* [PostgreSQL](/integrations/databases/PostgreSQL#add-credentials)
* [Redshift](/integrations/databases/Redshift#add-credentials)
* [Snowflake](/integrations/databases/Snowflake#add-credentials)
***
## Add SQL block to pipeline
1. Create a new pipeline or open an existing pipeline.
2. Add a data loader, transformer, or data exporter block.
3. Select `SQL`.
***
## Configure SQL block
There are 4 - 5 fields that must be configured for each SQL block:
| Field | Required | Description |
| -------------- | ------------------------ | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| Data provider | Yes | The database or data warehouse you want to execute your SQL commands in. |
| Profile | Yes | When you add your credentials to the `io_config.yaml` file, you added them under a key. That key is called the profile. Choose which set of credentials you want this SQL block to use. |
| Use raw SQL | No | You can write raw SQL and it’ll be executed as written in your data provider. |
| Database | Depends on data provider | Some data warehouses require that we explicitly state the name of the database we want to write to. If this is present, it’s required. The name of the table that is created follows this convention: `[database].[schema].[pipeline UUID]_[block UUID]`. |
| Schema to save | Yes | Every SQL block will save data to your data provider. The name of the table that is created follows this convention: `[schema].[pipeline UUID]_[block UUID]`. |
| Table | No | SQL blocks will automatically name your table for you using a naming convention (see the section `Automatic naming of tables` for more information). You can override this automatic naming convention by filling in a value in this field. |
| Write policy | Yes | How do you want to handle existing data with the same database, schema, and table name? See below for more information. |
#### Write policies
| Policy | Description |
| ------- | -------------------------------- |
| Append | Add rows to the existing table. |
| Replace | Delete the existing data. |
| Fail | Raise an error during execution. |
#### YAML configuration
You can also modify block configuration in pipeline's `metadata.yaml` file. Each block has a `configuration` field.
Example configuration
```yaml theme={null}
configuration:
data_provider: sqlserver
data_provider_profile: default
data_provider_schema: ''
export_write_policy: append
limit: 1000
limit_in_pipeline_run: 1
use_raw_sql: false
```
In addition to the fields mentioned in the table above. Here are some extra fields that can be included in the configuration:
| Field | Required | Description |
| ------------------------ | -------- | -------------------------------------------------------------------------------- |
| limit | No | The maximum number of rows to return in notebook. |
| limit\_in\_pipeline\_run | No | The maximum number of rows to return when running the block in the pipeline run. |
## Automatically created tables
Each SQL block will create a table in the data provider of your choice.
When you run a block, it’ll execute your SQL command, then store the results in
a table created in your database or data warehouse.
### Using raw SQL
If you toggle this setting, you’re responsible for writing the `CREATE TABLE` command and the
`INSERT` command.
For example, if a table already exists then you can write the `INSERT` statement:
```sql theme={null}
INSERT INTO mage.users
SELECT 1 AS id, 'Urza' AS username;
```
If the table doesn’t exist yet, you can write both the `CREATE TABLE` statement
and the `INSERT` statement:
```sql theme={null}
CREATE TABLE IF NOT EXISTS mage.users (
id BIGINT
, username VARCHAR(255)
);
WITH users AS (
SELECT
1 AS id
, 'Urza' AS username
)
INSERT INTO mage.users
SELECT
*
FROM users;
```
This SQL query will create a table named `mage.users` with 2 columns: `id` as a `BIGINT`
and `username` as a `VARCHAR(255)`.
Then, it’ll insert a single row into that table.
#### Required SQL statements
When writing raw SQL, you must at least 1 of the following statements:
* `SELECT`
```sql theme={null}
SELECT 1;
```
* `INSERT`
```sql theme={null}
INSERT INTO some_table
SELECT 1;
```
* `CREATE TABLE`
```sql theme={null}
CREATE TABLE some_table (id BIGINT);
```
* `DROP TABLE`
```sql theme={null}
DROP TABLE some_table;
```
* `UPDATE`
```sql theme={null}
UPDATE some_table
SET col1 = 'value1'
WHERE col2 = 'value2'
```
#### Multiple SQL statements
You can execute multiple SQL statements in a SQL block. Separate your SQL statements using a semi-colon (`;`).
### Automatic naming of tables
If you don’t choose the setting for using raw SQL,
the name of this automatically created table follows these conventions:
* If `Database` field is configured:
`[database].[schema].[pipeline UUID]_[block UUID]`
* If no `Database` field is configured: `[schema].[pipeline UUID]_[block UUID]`
Where pipeline UUID is the name of the current pipeline you’re editing.
Where block UUID is the name of the SQL block you are running.
### Upstream blocks
If your SQL block depends on upstream blocks that aren’t SQL blocks (e.g. Python
code blocks), then those blocks will also automatically create tables.
The name of those tables follows the same naming convention mentioned above.
***
## Variables
All SQL blocks have the following variables they can access in their query:
### `{{ execution_date }}`
The date and time the block is ran.
**Example**
```sql theme={null}
SELECT '{{ execution_date }}' AS today
```
**Result**
| `today` |
| :--------------------------- |
| `2022-09-24 23:01:08.376057` |
***
If a SQL block has 1 or more upstream blocks, then they have access to their
parent blocks’ output using the following variable:
### `{{ df_1 }}`
Depending on how many upstream blocks there are, the variable name changes. For
example, if there are 3 upstream blocks then there are 3 variables that can be
accessed:
* `{{ df_1 }}`
* `{{ df_2 }}`
* `{{ df_3 }}`
The SQL block UI will display which variable maps to which upstream block. By
convention, the 1st added upstream block will be `{{ df_1 }}`, and every
upstream block added after that will have an incrementing number in the variable
name after the prefix `df_`.
**Example**
```sql theme={null}
SELECT a.id , b.username FROM {{ df_1 }} AS a LEFT JOIN {{ df_2 }} AS b ON
a.id = b.user_id LIMIT 1
```
**Result**
| `id` | `username` |
| :--- | :----------------- |
| `1` | `Sorcerer supreme` |