`generate_surrogate_key` fails on SQL Server with one field

[jlkravitz]

The culprit line is here: https://github.com/dbt-labs/dbt-utils/blob/6ba7b660b1d1b4e3b41cb0cf6c3c0e4a70ae54e4/macros/sql/generate_surrogate_key.sql#L27C35-L27C35

select a, b, c, d, {{ dbt_utils.generate_surrogate_key(["a"]) }}
from my_table

results in error

('42000', '[42000] [Microsoft][ODBC Driver 18 for SQL Server][SQL Server]The concat function requires 2 to 254 arguments. (189) (SQLMoreResults)')```

I would expect this not to error.

[vinit2107]

Hi @jlkravitz ,
The issue is because of this code.

{% macro sqlserver__concat(fields) -%}
    concat({{ fields|join(', ') }})
{%- endmacro %}

You will need to add length validations here and remove concat if the length = 1 or add an empty string to the list (I prefer this). Happy to contribute if you want me to work on it, or you can take it forward 🙂.

[jlkravitz]

Oh great! I'm happy to take a stab at it.

@vinit2107 Just out of curiosity as I learn this codebase, where can I find the code that dispatches this call to concat to its SQL-backend specific implementation (e.g., SQL Server)?

[vinit2107]

Hi @jlkravitz ,
Sorry for the delay. You can find the code in dbt-core here.

[bleiho-oc]

Hi all, same error for the Micosoft Fabric Adapter.

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