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>
3.7 KiB
| layout | title | displayTitle | license |
|---|---|---|---|
| global | SHOW TABLES | SHOW TABLES | 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
The SHOW TABLES statement returns all the tables for an optionally specified database.
Additionally, the output of this statement may be filtered by an optional matching
pattern. If no database is specified then the tables are returned from the
current database.
Syntax
{% highlight sql %} SHOW TABLES [ { FROM | IN } database_name ] [ LIKE 'regex_pattern' ] {% endhighlight %}
Parameters
{ FROM | IN } database_name- Specifies the database name from which tables are listed.
LIKE regex_pattern-
Specifies the regular expression pattern that is used to filter out unwanted tables.
- Except for `*` and `|` character, the pattern works like a regex.
- `*` alone matches 0 or more characters and `|` is used to separate multiple different regexes, any of which can match.
- The leading and trailing blanks are trimmed in the input pattern before processing.
Example
{% highlight sql %} -- List all tables in default database SHOW TABLES; +--------+---------+-----------+ |database|tableName|isTemporary| +--------+---------+-----------+ | default| sam| false| | default| sam1| false| | default| suj| false| +--------+---------+-----------+
-- List all tables from userdb database SHOW TABLES FROM userdb; +--------+---------+-----------+ |database|tableName|isTemporary| +--------+---------+-----------+ | userdb| user1| false| | userdb| user2| false| +--------+---------+-----------+
-- List all tables in userdb database SHOW TABLES IN userdb; +--------+---------+-----------+ |database|tableName|isTemporary| +--------+---------+-----------+ | userdb| user1| false| | userdb| user2| false| +--------+---------+-----------+
-- List all tables from default database matching the pattern sam*
SHOW TABLES FROM default LIKE 'sam*';
+--------+---------+-----------+
|database|tableName|isTemporary|
+--------+---------+-----------+
| default| sam| false|
| default| sam1| false|
+--------+---------+-----------+
-- List all tables matching the pattern sam*|suj
SHOW TABLES LIKE 'sam*|suj';
+--------+---------+-----------+
|database|tableName|isTemporary|
+--------+---------+-----------+
| default| sam| false|
| default| sam1| false|
| default| suj| false|
+--------+---------+-----------+
{% endhighlight %}