Error to update table in Big Query using External Table and Subquery

Question

I need to UPDATE a boolean type column in a table ( table_bq ) in Big Query using an External Table ( external_table ). The problem is: the column I need to update will be updated only if another column from the table_bq matches with the column from the external_table , for that I need to use the LIKE statement.

I wrote this query below.

UPDATE table_bq                   
SET table_bq.column1 = True                                                               
WHERE table_bq.column2 = (SELECT
    table_bq.column2                                                                     
    FROM
      table_bq                               
    INNER JOIN
       external_table ON UPPER(table_bq.column2) LIKE CONCAT('%',UPPER(external_table.column),'%'));

But I'm getting the following error: Scalar subquery produced more than one element.

Does anybody know how I can fix the query?

Answer 1

I have looked at the documentation and it states that you cannot update an external table but it does not say that you cannot use an external table in a normal multi table update so I would try -

UPDATE table_bq
INNER JOIN external_table
    ON UPPER(table_bq.column2) LIKE CONCAT('%',UPPER(external_table.column),'%'))
SET table_bq.column1 = True

but if that is not allowed you will have to change = to IN for the subquery as it returns multiple rows -

WHERE table_bq.column2 IN (SELECT