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Learn how to utilize the `CREATE EXTERNAL TABLE` DDL statement in BigQuery to define and query external data sources seamlessly.
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How to Use CREATE EXTERNAL TABLE DDL Statement in BigQuery

BigQuery is a powerful data warehouse that enables fast SQL queries using the processing infrastructure of Google. One of its key features is the ability to create and query external tables. Using the CREATE EXTERNAL TABLE Data Definition Language (DDL) statement, you can quickly integrate and analyze data from external sources without the need to import it directly into BigQuery storage.

What is CREATE EXTERNAL TABLE?

The CREATE EXTERNAL TABLE statement allows you to define a table in BigQuery that references data stored outside of BigQuery. This is particularly useful for data that resides in Google Cloud Storage, Google Drive, or other external sources. This approach not only saves storage costs but also simplifies the process of querying large datasets stored outside BigQuery.

Syntax Overview

Here's the general syntax for the CREATE EXTERNAL TABLE statement:

[[See Video to Reveal this Text or Code Snippet]]

Parameters Explained:

IF NOT EXISTS: Ensures the table is only created if it does not already exist.

project_name.dataset_name.table_name: Specifies the full name of the table you are creating.

OPTIONS: Lists the format of the data file and its location.

Example

Let's create an external table that references a CSV file stored in Google Cloud Storage:

[[See Video to Reveal this Text or Code Snippet]]

This statement creates an external table named my_external_table in the dataset my_dataset, sourcing data from the CSV file located at gs://my-bucket/my-data.csv.

Benefits of Using External Tables

Cost-Efficiency: By querying external tables, you avoid the costs associated with data storage in BigQuery.

Flexibility: You can query external data without needing to import it first, thereby maintaining a single source of truth.

Scalability: Handle large datasets efficiently by leveraging Google's infrastructure.

Use Cases

Data Integration: External tables are ideal for creating a unified view of data stored across different platforms.

Temporary Queries: When you need to run ad-hoc queries on datasets that don't require repeated access, external tables offer a seamless approach without additional storage overhead.

Data Pipeline Efficiency: When linking BigQuery with other systems, manipulating data directly in its original location saves ETL process time and complexity.

In conclusion, the CREATE EXTERNAL TABLE DDL statement in BigQuery is a versatile tool that enhances your ability to work with diverse data sources efficiently and effectively.

Conclusion

The CREATE EXTERNAL TABLE statement is indispensable for those looking to extend BigQuery’s analytical capabilities to external data. By understanding how to define and use these external tables, you can optimize both performance and cost, making your data operations smoother and more effective.

Happy querying!