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>
4.3 KiB
| layout | title | displayTitle | license |
|---|---|---|---|
| global | SHOW FUNCTIONS | SHOW FUNCTIONS | 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
Returns the list of functions after applying an optional regex pattern.
Given number of functions supported by Spark is quite large, this statement
in conjunction with describe function
may be used to quickly find the function and understand its usage. The LIKE
clause is optional and supported only for compatibility with other systems.
Syntax
{% highlight sql %} SHOW [ function_kind ] FUNCTIONS ( [ LIKE ] function_name | regex_pattern ) {% endhighlight %}
Parameters
function_kind-
Specifies the name space of the function to be searched upon. The valid name spaces are :
- USER - Looks up the function(s) among the user defined functions.
- SYSTEM - Looks up the function(s) among the system defined functions.
- ALL - Looks up the function(s) among both user and system defined functions.
function_name-
Specifies a name of an existing function in the system. The function name may be
optionally qualified with a database name. If `function_name` is qualified with
a database then the function is resolved from the user specified database, otherwise
it is resolved from the current database.
Syntax:[database_name.]function_name regex_pattern-
Specifies a regular expression pattern that is used to limit the results of the
statement.
- Only `*` and `|` are allowed as wildcard pattern.
- Excluding `*` and `|` the remaining pattern follows the regex semantics.
- The leading and trailing blanks are trimmed in the input pattern before processing.
Examples
{% highlight sql %}
-- List a system function trim by searching both user defined and system
-- defined functions.
SHOW FUNCTIONS trim;
+--------+
|function|
+--------+
| trim|
+--------+
-- List a system function concat by searching system defined functions.
SHOW SYSTEM FUNCTIONS concat;
+--------+
|function|
+--------+
| concat|
+--------+
-- List a qualified function max from database salesdb.
SHOW SYSTEM FUNCTIONS salesdb.max;
+--------+
|function|
+--------+
| max|
+--------+
-- List all functions starting with t
SHOW FUNCTIONS LIKE 't*';
+-----------------+
| function|
+-----------------+
| tan|
| tanh|
| timestamp|
| tinyint|
| to_csv|
| to_date|
| to_json|
| to_timestamp|
|to_unix_timestamp|
| to_utc_timestamp|
| transform|
| transform_keys|
| transform_values|
| translate|
| trim|
| trunc|
| typeof|
+-----------------+
-- List all functions starting with yea or windo
SHOW FUNCTIONS LIKE 'yea*|windo*';
+--------+
|function|
+--------+
| window|
| year|
+--------+
-- Use normal regex pattern to list function names that has 4 characters
-- with t as the starting character.
SHOW FUNCTIONS LIKE 't[a-z][a-z][a-z]';
+--------+
|function|
+--------+
| tanh|
| trim|
+--------+
{% endhighlight %}