BigQuery SQL - UNION ALL

BigQuery supports UNION ALL clause in standard SQL though it doesn't support UNION clause.

BigQuery UNION ALL

The following statement shows an example of UNION ALL clause in SELECT statement.

SELECT
  'A' AS Col1,
  1 AS Col2
UNION ALL
SELECT
  'A' AS Col1,
  1 AS Col2

Output (in JSON format):

[
  {
    "Col1": "A",
    "Col2": "1"
  },
  {
    "Col1": "A",
    "Col2": "1"
  }
]

UNION DISTINCT

UNION DISTINCT is similar as UNION (without ALL) in other databases:

SELECT
    'A' AS Col1,
    1 AS Col2
  UNION DISTINCT
  SELECT
    'A' AS Col1,
    1 AS Col2

Output (in JSON format):

[
  {
    "Col1": "A",
    "Col2": "1"
  }
]