75da05038b
### What changes were proposed in this pull request? Remove two leading spaces from sql tables. ### Why are the changes needed? Follow the format of other references such as https://docs.snowflake.com/en/sql-reference/constructs/join.html, https://docs.oracle.com/cd/B19306_01/server.102/b14200/statements_10002.htm, https://www.postgresql.org/docs/10/sql-select.html. ### Does this PR introduce any user-facing change? before ``` SELECT * FROM test; +-+ ... +-+ ``` after ``` SELECT * FROM test; +-+ ... +-+ ``` ### How was this patch tested? Manually build and check Closes #28348 from huaxingao/sql-format. Authored-by: Huaxin Gao <huaxing@us.ibm.com> Signed-off-by: gatorsmile <gatorsmile@gmail.com>
197 lines
3.7 KiB
Markdown
197 lines
3.7 KiB
Markdown
---
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layout: global
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title: Set Operators
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displayTitle: Set Operators
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license: |
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Licensed to the Apache Software Foundation (ASF) under one or more
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contributor license agreements. See the NOTICE file distributed with
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this work for additional information regarding copyright ownership.
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The ASF licenses this file to You under the Apache License, Version 2.0
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(the "License"); you may not use this file except in compliance with
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the License. You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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---
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### Description
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Set operators are used to combine two input relations into a single one. Spark SQL supports three types of set operators:
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- `EXCEPT` or `MINUS`
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- `INTERSECT`
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- `UNION`
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Note that input relations must have the same number of columns and compatible data types for the respective columns.
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### EXCEPT
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`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`.
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#### Syntax
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{% highlight sql %}
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[ ( ] relation [ ) ] EXCEPT | MINUS [ ALL | DISTINCT ] [ ( ] relation [ ) ]
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{% endhighlight %}
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#### Examples
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{% highlight sql %}
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-- Use number1 and number2 tables to demonstrate set operators in this page.
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SELECT * FROM number1;
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+---+
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+---+
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+---+
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SELECT * FROM number2;
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+---+
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+---+
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+---+
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SELECT c FROM number1 EXCEPT SELECT c FROM number2;
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+---+
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+---+
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+---+
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SELECT c FROM number1 MINUS SELECT c FROM number2;
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+---+
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+---+
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+---+
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SELECT c FROM number1 EXCEPT ALL (SELECT c FROM number2);
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+---+
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+---+
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+---+
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SELECT c FROM number1 MINUS ALL (SELECT c FROM number2);
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+---+
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| c|
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+---+
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+---+
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{% endhighlight %}
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### INTERSECT
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`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.
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#### Syntax
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{% highlight sql %}
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[ ( ] relation [ ) ] INTERSECT [ ALL | DISTINCT ] [ ( ] relation [ ) ]
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{% endhighlight %}
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#### Examples
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{% highlight sql %}
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(SELECT c FROM number1) INTERSECT (SELECT c FROM number2);
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+---+
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+---+
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+---+
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(SELECT c FROM number1) INTERSECT DISTINCT (SELECT c FROM number2);
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+---+
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+---+
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+---+
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(SELECT c FROM number1) INTERSECT ALL (SELECT c FROM number2);
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+---+
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+---+
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+---+
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{% endhighlight %}
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### UNION
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`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.
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#### Syntax
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{% highlight sql %}
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[ ( ] relation [ ) ] UNION [ ALL | DISTINCT ] [ ( ] relation [ ) ]
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{% endhighlight %}
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### Examples
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{% highlight sql %}
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(SELECT c FROM number1) UNION (SELECT c FROM number2);
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+---+
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+---+
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+---+
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(SELECT c FROM number1) UNION DISTINCT (SELECT c FROM number2);
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+---+
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+---+
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+---+
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SELECT c FROM number1 UNION ALL (SELECT c FROM number2);
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+---+
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+---+
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+---+
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{% endhighlight %}
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### Related Statements
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* [SELECT Statement](sql-ref-syntax-qry-select.html)
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