Updating a table in bigquery using DBT - google-bigquery

Question

I am trying to update a table in bigquery using DBT. The below command executes in bigquery;
Update {{ ref('my_table') }}
SET variable = 'value'
WHERE lower(variable) LIKE '%XX%' or lower(variable) like '%YY%'
However when I run it in DBT I get the following error
Server error: Database Error in rpc request (from remote system)
Syntax error: Expected end of input but got keyword LIMIT at [4:1]
Does anyone know why this is happening and how to resolve?

Answer 1

It's a little unintuitive at first I know but with dbt, every model is a select statement.
You should instead think of doing something like:
with cte as (
select * from {{ ref('my_table') }}
where <criteria>
)
select col1,
col2,
'value' as col3
from cte
Or possibly even simpler:
SELECT
'value' as variable
FROM {{ ref('my_table') }}
WHERE lower(variable) LIKE '%XX%' or lower(variable) like '%YY%'
Simply because during the dbt run cycle, the new values will be materialized into the new model.
However, if you are looking for ways to clean underlying tables in a DRY way, I'd highly recommend this thread Modeling SQL Update Statements from the dbt discourse for some patterns on managing statements which handle specific value cleaning. Example from Kyle Ries:
{% set mappings = {'something': 'boo', 'something-else': 'boo-else'} %}
with source as (
select * from {{ ref(‘stg_foobar’) }}
),
final as (
select
case
{% for old, new in mappings %}
when other_column like ‘{{old}}’ then ‘{{new}}’
{% endfor %}
end as column_name
from
source
)
select * from final