### What changes were proposed in this pull request? Remove the unneeded embedded inline HTML markup by using the basic markdown syntax. Please see #28414 ### Why are the changes needed? Make the doc cleaner and easily editable by MD editors. ### Does this PR introduce _any_ user-facing change? No ### How was this patch tested? Manually build and check Closes #28451 from huaxingao/html_cleanup. Authored-by: Huaxin Gao <huaxing@us.ibm.com> Signed-off-by: Sean Owen <srowen@gmail.com>
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layout | title | displayTitle | license |
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global | Set Operators | Set Operators | Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements. See the NOTICE file distributed with this work for additional information regarding copyright ownership. The ASF licenses this file to You under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0 Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License. |
Description
Set operators are used to combine two input relations into a single one. Spark SQL supports three types of set operators:
EXCEPT
orMINUS
INTERSECT
UNION
Note that input relations must have the same number of columns and compatible data types for the respective columns.
EXCEPT
EXCEPT
and EXCEPT ALL
return the rows that are found in one relation but not the other. EXCEPT
(alternatively, EXCEPT DISTINCT
) takes only distinct rows while EXCEPT ALL
does not remove duplicates from the result rows. Note that MINUS
is an alias for EXCEPT
.
Syntax
[ ( ] relation [ ) ] EXCEPT | MINUS [ ALL | DISTINCT ] [ ( ] relation [ ) ]
Examples
-- Use number1 and number2 tables to demonstrate set operators in this page.
SELECT * FROM number1;
+---+
| c|
+---+
| 3|
| 1|
| 2|
| 2|
| 3|
| 4|
+---+
SELECT * FROM number2;
+---+
| c|
+---+
| 5|
| 1|
| 2|
| 2|
+---+
SELECT c FROM number1 EXCEPT SELECT c FROM number2;
+---+
| c|
+---+
| 3|
| 4|
+---+
SELECT c FROM number1 MINUS SELECT c FROM number2;
+---+
| c|
+---+
| 3|
| 4|
+---+
SELECT c FROM number1 EXCEPT ALL (SELECT c FROM number2);
+---+
| c|
+---+
| 3|
| 3|
| 4|
+---+
SELECT c FROM number1 MINUS ALL (SELECT c FROM number2);
+---+
| c|
+---+
| 3|
| 3|
| 4|
+---+
INTERSECT
INTERSECT
and INTERSECT ALL
return the rows that are found in both relations. INTERSECT
(alternatively, INTERSECT DISTINCT
) takes only distinct rows while INTERSECT ALL
does not remove duplicates from the result rows.
Syntax
[ ( ] relation [ ) ] INTERSECT [ ALL | DISTINCT ] [ ( ] relation [ ) ]
Examples
(SELECT c FROM number1) INTERSECT (SELECT c FROM number2);
+---+
| c|
+---+
| 1|
| 2|
+---+
(SELECT c FROM number1) INTERSECT DISTINCT (SELECT c FROM number2);
+---+
| c|
+---+
| 1|
| 2|
+---+
(SELECT c FROM number1) INTERSECT ALL (SELECT c FROM number2);
+---+
| c|
+---+
| 1|
| 2|
| 2|
+---+
UNION
UNION
and UNION ALL
return the rows that are found in either relation. UNION
(alternatively, UNION DISTINCT
) takes only distinct rows while UNION ALL
does not remove duplicates from the result rows.
Syntax
[ ( ] relation [ ) ] UNION [ ALL | DISTINCT ] [ ( ] relation [ ) ]
Examples
(SELECT c FROM number1) UNION (SELECT c FROM number2);
+---+
| c|
+---+
| 1|
| 3|
| 5|
| 4|
| 2|
+---+
(SELECT c FROM number1) UNION DISTINCT (SELECT c FROM number2);
+---+
| c|
+---+
| 1|
| 3|
| 5|
| 4|
| 2|
+---+
SELECT c FROM number1 UNION ALL (SELECT c FROM number2);
+---+
| c|
+---+
| 3|
| 1|
| 2|
| 2|
| 3|
| 4|
| 5|
| 1|
| 2|
| 2|
+---+