Source-Link: googleapis/synthtool@25083af
Post-Processor: gcr.io/cloud-devrel-public-resources/owlbot-python:latest@sha256:e6cbd61f1838d9ff6a31436dfc13717f372a7482a82fc1863ca954ec47bff8c8

Co-authored-by: Owl Bot <gcf-owl-bot[bot]@users.noreply.github.com>

This change adds support for DML returning clauses and includes a few prerequisite changes.

I would suggest reviewing commit-by-commit. The commit messages provide additional context and are reproduced below,

### feat: Support custom endpoint when running tests

By setting the `GOOGLE_CLOUD_TESTS_SPANNER_HOST` environment variable you can now run tests against an alternate Spanner API endpoint. This is particularly useful for running system tests against a pre-production deployment.

### refactor(dbapi): Remove most special handling of INSERTs

For historical reasons it seems the INSERT codepath and that for UPDATE/DELETE were separated, but today there appears to be no practical differences in how these DML statements are handled. This change removes most of the special handling for INSERTs and uses existing methods for UPDATEs/DELETEs instead. The one remaining exception is the automatic addition of a WHERE clause to UPDATE and DELETE statements lacking one, which does not apply to INSERT statements.

### feat(dbapi): Add full support for rowcount

Previously, rowcount was only available after executing an UPDATE or DELETE in autocommit mode. This change extends this support so that a rowcount is available for all DML statements, regardless of whether autocommit is enabled.

### feat: Add support for returning clause in DML

This change adds support and tests for a returning clause in DML statements. This is done by moving executing of all DML to use `execute_sql`, which is already used when not in autocommit mode.

Source-Link: googleapis/synthtool@6ed3a83
Post-Processor: gcr.io/cloud-devrel-public-resources/owlbot-python:latest@sha256:3abfa0f1886adaf0b83f07cb117b24a639ea1cb9cffe56d43280b977033563eb

Co-authored-by: Owl Bot <gcf-owl-bot[bot]@users.noreply.github.com>

Samples are provided for INSERT, DELETE, and UPDATE in both GoogleSQL and PostgreSQL dialects. To provide a more compelling example for the INSERT case, a generated column has been added in the "create_database" example so that the generated value can be returned in the INSERT examples.

Co-authored-by: release-please[bot] <55107282+release-please[bot]@users.noreply.github.com>