我可以在表名中使用查询参数吗？

Question

我想做一些事情：

SELECT some_things
FROM `myproject.mydataset.mytable_@suffix`

但这不起作用，因为参数未在表名内展开。

这确实有效，使用通配符表：

SELECT some_things
FROM `myproject.mydataset.mytable_*`
WHERE _TABLE_SUFFIX = @suffix

但是，它有一些问题：

• If I mistype the parameter, this query silently returns zero rows, rather than yelling at me loudly.

• Query caching stops working when querying with a wildcard.

• If other tables exist with the mytable_ prefix, they must have the same schema, even if they don't match the suffix. Otherwise, weird stuff happens. It seems like BigQuery either computes the union of all columns, or takes the schema of an arbitrary table; it's not documented and I didn't look at it in detail.

Is there a better way to query a single table whose name depends on a query parameter?

Answer 1

是的，你可以，这是一个有效的示例：

DECLARE tablename STRING;
DECLARE tableQuery STRING;

##get list of tables
CREATE TEMP TABLE tableNames as select table_name from nomo_nausea.INFORMATION_SCHEMA.TABLES where table_name not in ('_sdc_primary_keys', '_sdc_rejected', 'fba_all_order_report_data');

WHILE (select count(*) from tableNames) >= 1 DO
  SET tablename = (select table_name from tableNames LIMIT 1);
  ##build dataset + table name
  SET tableQuery = CONCAT('nomo_nausea.' , tablename);
  ##use concat to build string and execute
  EXECUTE IMMEDIATE CONCAT('SELECT * from `', tableQuery, '` where _sdc_deleted_at is not null');
  DELETE FROM tableNames where table_name = tablename;
END WHILE;