When using Google Apps Script to connect to a PostgreSQL (PSQL) database, you need to provide IP address ranges so that Apps Script's servers can connect to your database. This ensures secure and reliable communication between your script and the database.

Before running your script, complete the following steps:

1. Copy the URL that was assigned to your database. It should have the form of `jdbc:google:mysql://subname`, where `subname` is the MySQL Instance connection name.

2. Allow-list certain IP ranges for access to your database. This is a crucial step in setting up secure connections.

To connect to Cloud SQL SQL Server, see 'Jdbc.getConnection(url)'(https://cloud.google.com/sql/docs/mysql/connect-connect-to-instance#connecting-using-jdbc). Listed on the Cloud SQL instance Overview page in the Google Cloud Console, you'll find the database URL with the form `jdbc:google:mysql://subname`, where `subname` is the MySQL Instance connection name.

There are two ways of establishing a connection with a Google Cloud SQL database using Apps Script's JDBC service:

1. Connecting using Jdbc.getConnection(url): This method requires you to allow-list a set of IP ranges for access to your database.

2. Recommended: Connecting using Jdbc.getCloudSqlConnection(url): This method also requires you to allow-list certain IP ranges, but it is recommended as it provides better security and reliability.

To create a Google Cloud SQL instance, follow the steps listed in the Cloud SQL Quickstart. Google Cloud SQL lets you create relational databases that live on the cloud, so you can focus on building your application without worrying about database management.

When updating an external database with JDBC, your script must open a connection to the database and then make changes by sending SQL statements. The JDBC service supports Google Cloud SQL MySQL, PostgreSQL, Microsoft SQL Server, and other popular databases.

To establish connections, use TLS 1.2 or higher. Note that versions 1.0 and 1.1 of the TLS security protocol are disabled for security reasons.

In summary, connecting to a PSQL database using Google Apps Script requires providing IP address ranges and allowing-listing certain IP addresses. By following these steps, you can establish secure connections to your database and build powerful applications with ease.

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