fb1053d14a
### What changes were proposed in this pull request? Document SHOW DATABASES statement in SQL Reference Guide. ### Why are the changes needed? Currently Spark lacks documentation on the supported SQL constructs causing confusion among users who sometimes have to look at the code to understand the usage. This is aimed at addressing this issue. ### Does this PR introduce any user-facing change? Yes. **Before:** There was no documentation for this. **After.** <img width="1234" alt="Screen Shot 2019-08-28 at 11 43 36 PM" src="https://user-images.githubusercontent.com/14225158/63916727-dd600380-c9ed-11e9-8372-789110c9d2dc.png"> <img width="1234" alt="Screen Shot 2019-08-28 at 11 43 57 PM" src="https://user-images.githubusercontent.com/14225158/63916734-e0f38a80-c9ed-11e9-8ad4-d854febeaab8.png"> <img width="1234" alt="Screen Shot 2019-08-28 at 11 44 13 PM" src="https://user-images.githubusercontent.com/14225158/63916740-e4871180-c9ed-11e9-9cfc-199cd8a64852.png"> ### How was this patch tested? Tested using jykyll build --serve Closes #25526 from dilipbiswal/ref-doc-show-db. Authored-by: Dilip Biswal <dbiswal@us.ibm.com> Signed-off-by: Xiao Li <gatorsmile@gmail.com>
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| layout | title | displayTitle | license |
|---|---|---|---|
| global | SHOW DATABASES | SHOW DATABASES | 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
Lists the databases that match an optionally supplied string pattern. If no
pattern is supplied then the command lists all the databases in the system.
Please note that the usage of SCHEMAS and DATABASES are interchangable
and mean the same thing.
Syntax
{% highlight sql %} SHOW {DATABASES|SCHEMAS} [LIKE string_pattern] {% endhighlight %}
Parameters
LIKE string_pattern-
Specifies a string pattern that is used to match the databases in the system. In
the specified string pattern
'*'matches any number of characters.
Examples
{% highlight sql %}
-- Create database. Assumes a database named default already exists in
-- the system.
CREATE DATABASE payroll_db;
CREATE DATABASE payments_db;
-- Lists all the databases.
SHOW DATABASES;
+------------+
|databaseName|
+------------+
| default|
| payments_db|
| payroll_db|
+------------+
-- Lists databases with name starting with string pattern pay
SHOW DATABASES LIKE 'pay*';
+------------+
|databaseName|
+------------+
| payments_db|
| payroll_db|
+------------+
-- Lists all databases. Keywords SCHEMAS and DATABASES are interchangeable.
SHOW SCHEMAS;
+------------+
|databaseName|
+------------+
| default|
| payments_db|
| payroll_db|
+------------+
{% endhighlight %}