179289f0bf
### What changes were proposed in this pull request? This PR intends to clean up the SQL documents in `doc/sql-ref*`. Main changes are as follows; - Fixes wrong syntaxes and capitalize sub-titles - Adds some DDL queries in `Examples` so that users can run examples there - Makes query output in `Examples` follows the `Dataset.showString` (right-aligned) format - Adds/Removes spaces, Indents, or blank lines to follow the format below; ``` --- license... --- ### Description Writes what's the syntax is. ### Syntax {% highlight sql %} SELECT... WHERE... // 4 indents after the second line ... {% endhighlight %} ### Parameters <dl> <dt><code><em>Param Name</em></code></dt> <dd> Param Description </dd> ... </dl> ### Examples {% highlight sql %} -- It is better that users are able to execute example queries here. -- So, we prepare test data in the first section if possible. CREATE TABLE t (key STRING, value DOUBLE); INSERT INTO t VALUES ('a', 1.0), ('a', 2.0), ('b', 3.0), ('c', 4.0); -- query output has 2 indents and it follows the `Dataset.showString` -- format (right-aligned). SELECT * FROM t; +---+-----+ |key|value| +---+-----+ | a| 1.0| | a| 2.0| | b| 3.0| | c| 4.0| +---+-----+ -- Query statements after the second line have 4 indents. SELECT key, SUM(value) FROM t GROUP BY key; +---+----------+ |key|sum(value)| +---+----------+ | c| 4.0| | b| 3.0| | a| 3.0| +---+----------+ ... {% endhighlight %} ### Related Statements * [XXX](xxx.html) * ... ``` ### Why are the changes needed? The most changes of this PR are pretty minor, but I think the consistent formats/rules to write documents are important for long-term maintenance in our community ### Does this PR introduce any user-facing change? Yes. ### How was this patch tested? Manually checked. Closes #28151 from maropu/MakeRightAligned. Authored-by: Takeshi Yamamuro <yamamuro@apache.org> Signed-off-by: Sean Owen <srowen@gmail.com>
112 lines
3.7 KiB
Markdown
112 lines
3.7 KiB
Markdown
---
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layout: global
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title: SHOW TABLES
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displayTitle: SHOW TABLES
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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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The `SHOW TABLES` statement returns all the tables for an optionally specified database.
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Additionally, the output of this statement may be filtered by an optional matching
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pattern. If no database is specified then the tables are returned from the
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current database.
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### Syntax
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{% highlight sql %}
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SHOW TABLES [ { FROM | IN } database_name ] [ LIKE 'regex_pattern' ]
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{% endhighlight %}
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### Parameters
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<dl>
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<dt><code><em>{ FROM | IN } database_name</em></code></dt>
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<dd>
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Specifies the database name from which tables are listed.
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</dd>
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<dt><code><em>LIKE regex_pattern</em></code></dt>
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<dd>
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Specifies the regular expression pattern that is used to filter out unwanted tables.
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<ul>
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<li> Except for `*` and `|` character, the pattern works like a regex.</li>
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<li> `*` alone matches 0 or more characters and `|` is used to separate multiple different regexes,
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any of which can match. </li>
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<li> The leading and trailing blanks are trimmed in the input pattern before processing.</li>
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</ul>
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</dd>
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</dl>
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### Example
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{% highlight sql %}
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-- List all tables in default database
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SHOW TABLES;
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+--------+---------+-----------+
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|database|tableName|isTemporary|
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+--------+---------+-----------+
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| default| sam| false|
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| default| sam1| false|
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| default| suj| false|
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+--------+---------+-----------+
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-- List all tables from userdb database
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SHOW TABLES FROM userdb;
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+--------+---------+-----------+
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|database|tableName|isTemporary|
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+--------+---------+-----------+
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| userdb| user1| false|
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| userdb| user2| false|
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+--------+---------+-----------+
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-- List all tables in userdb database
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SHOW TABLES IN userdb;
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+--------+---------+-----------+
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|database|tableName|isTemporary|
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+--------+---------+-----------+
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| userdb| user1| false|
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| userdb| user2| false|
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+--------+---------+-----------+
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-- List all tables from default database matching the pattern `sam*`
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SHOW TABLES FROM default LIKE 'sam*';
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+--------+---------+-----------+
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|database|tableName|isTemporary|
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+--------+---------+-----------+
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| default| sam| false|
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| default| sam1| false|
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+--------+---------+-----------+
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-- List all tables matching the pattern `sam*|suj`
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SHOW TABLES LIKE 'sam*|suj';
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+--------+---------+-----------+
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|database|tableName|isTemporary|
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+--------+---------+-----------+
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| default| sam| false|
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| default| sam1| false|
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| default| suj| false|
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+--------+---------+-----------+
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{% endhighlight %}
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### Related Statements
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* [CREATE TABLE](sql-ref-syntax-ddl-create-table.html)
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* [DROP TABLE](sql-ref-syntax-ddl-drop-table.html)
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* [CREATE DATABASE](sql-ref-syntax-ddl-create-database.html)
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* [DROP DATABASE](sql-ref-syntax-ddl-drop-database.html)
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