Address error in SQL query

[dgomes]

Breaking change

Proposed change

Type of change

• Dependency upgrade
• Bugfix (non-breaking change which fixes an issue)
• New integration (thank you!)
• New feature (which adds functionality to an existing integration)
• Breaking change (fix/feature causing existing functionality to break)
• Code quality improvements to existing code or addition of tests

Example entry for configuration.yaml:

# Example configuration.yaml
sensor:
  - platform: sql
    scan_interval: 10
    queries:
      - name: sensor_for_unknown_switch
        query: "SELECT last_changed FROM states WHERE entity_id='switch.unknown_name' AND state='on' ORDER BY last_changed DESC LIMIT 1;"
        column: 'last_changed'
        value_template: "{{ as_timestamp(value + 'Z') | timestamp_custom('%a %b %-d %H:%M') }}"

Additional information

• This PR fixes or closes issue: fixes sql: Error on device update! #36707
• This PR is related to issue:
• Link to documentation pull request:

Checklist

• The code change is tested and works locally.
• Local tests pass. Your PR cannot be merged unless tests pass
• There is no commented out code in this PR.
• I have followed the development checklist
• The code has been formatted using Black (black --fast homeassistant tests)
• Tests have been added to verify that the new code works.

If user exposed functionality or configuration variables are added/changed:

• Documentation added/updated for www.home-assistant.io

If the code communicates with devices, web services, or third-party tools:

• The manifest file has all fields filled out correctly.
  Updated and included derived files by running: python3 -m script.hassfest.
• New or updated dependencies have been added to requirements_all.txt.
  Updated by running python3 -m script.gen_requirements_all.
• Untested files have been added to .coveragerc.

The integration reached or maintains the following Integration Quality Scale:

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To help with the load of incoming pull requests:

• I have reviewed two other open pull requests in this repository.

[MartinHjelmare]

I'd default data to None and add a guard if data is None with error log before finishing the update.

[MartinHjelmare]

Or maybe try to rewrite so data is not unbound and raise an error if it's None?

[MartinHjelmare]

Maybe return early if result is empty?

[dgomes]

rowcount can't be trusted https://docs.sqlalchemy.org/en/13/core/connections.html?highlight=returns_rows#sqlalchemy.engine.ResultProxy.rowcount

I'm going with the initialisation of data

[MartinHjelmare]

Looks good!

[springstan]

Can we merge this and should we tag it for beta?