github.com/mithrandie/csvq@v1.18.1/docs/_posts/2006-01-02-set-operators.md (about)

     1  ---
     2  layout: default
     3  title: Set Operators - Reference Manual - csvq
     4  category: reference
     5  ---
     6  
     7  # Set Operators
     8  
     9  | operator | description |
    10  | :- | :- |
    11  | [UNION](#union) | Return the union of result sets |
    12  | [EXCEPT](#except)   | Return the relative complement of result sets  |
    13  | [INTERSECT](#intersect) | Return the intersection of result sets |
    14  
    15  A set operation combines result sets retrieved by select queries into a single result set.
    16  If the ALL keyword is not specified, the result is distinguished.
    17  
    18  ## UNION
    19  {: #union}
    20  
    21  ```sql
    22  select_query UNION [ALL] select_query
    23  ```
    24  
    25  _select_query_
    26  : [select_set_entity]({{ '/reference/select-query.html' | relative_url }})
    27  
    28  Return all records of both result sets.
    29  
    30  ## EXCEPT
    31  {: #except}
    32  
    33  ```sql
    34  select_query EXCEPT [ALL] select_query
    35  ```
    36  
    37  _select_query_
    38  : [select_set_entity]({{ '/reference/select-query.html' | relative_url }})
    39  
    40  Return records of the result set of the left-hand side query that do not appear in the result set of the right-hand side query.
    41  
    42  ## INTERSECT
    43  {: #intersect}
    44  
    45  ```sql
    46  select_query INTERSECT [ALL] select_query
    47  ```
    48  
    49  _select_query_
    50  : [select_set_entity]({{ '/reference/select-query.html' | relative_url }})
    51  
    52  Return only records that appear in both result sets.