What's the process of altering a Snowflake table to add a new column? Provide the SQL syntax.
To alter a Snowflake table and add a new column, you can use the **`ALTER TABLE`** statement with the **`ADD COLUMN`** clause. Here's the process along with the SQL syntax:
1. **Connect to Snowflake:** Ensure you're connected to your Snowflake account using a SQL client or Snowflake web interface.
2. **Identify the Table:** Determine the name of the table you want to alter and add a new column to.
3. **Write the SQL Statement:** Use the **`ALTER TABLE`** statement with the **`ADD COLUMN`** clause to add the new column. Here's the syntax:
```sql
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ALTER TABLE table_name
ADD COLUMN new_column_name data_type [DEFAULT default_value] [NULL | NOT NULL] [COMMENT 'column_comment'];
```
- **`table_name`**: Replace this with the name of the table you want to alter.
- **`new_column_name`**: Replace this with the name you want to give to the new column.
- **`data_type`**: Specify the data type of the new column (e.g., INT, VARCHAR(255), DATE, etc.).
- **`DEFAULT default_value`**: Optional. Set a default value for the new column.
- **`NULL`** or **`NOT NULL`**: Specify whether the new column can have NULL values or not.
- **`COMMENT 'column_comment'`**: Optional. Add a comment describing the purpose of the new column.
1. **Execute the Statement:** Run the SQL statement in your Snowflake SQL client or web interface.
Here's an example SQL statement that adds a new column named **`Email`** of data type **`VARCHAR(255)`** to a table named **`Customers`**:
```sql
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ALTER TABLE Customers
ADD COLUMN Email VARCHAR(255) NULL COMMENT 'Email address of the customer';
```
In this example, we're adding a new column called **`Email`** with a **`VARCHAR`** data type that can hold up to 255 characters. The column is allowed to have NULL values, and we've provided a comment to describe the column's purpose.
Remember to replace **`Customers`** with the actual name of your table and adjust the column name, data type, and other attributes as needed for your use case.
