<stránka
	xmlns="https://trac.frantovo.cz/xml-web-generator/wiki/xmlns/strana"
	xmlns:m="https://trac.frantovo.cz/xml-web-generator/wiki/xmlns/makro">
	
	<nadpis>Hello Wordl!</nadpis>
	<perex>generating relational data from CLI arguments</perex>
	<m:pořadí-příkladu>00100</m:pořadí-příkladu>

	<text xmlns="http://www.w3.org/1999/xhtml">
		
		<p>
			Let's start with an obligatory Hello World example.
		</p>
		
		<m:pre jazyk="bash"><![CDATA[relpipe-in-cli generate "relation_from_cli" 3 \
	"a" "integer" \
	"b" "string" \
	"c" "boolean" \
	"1" "Hello" "true" \
	"2" "World!" "false"]]></m:pre>
	
		<p>
			This command generates relational data.
			In order to see them, we need to convert them to some other format.
			For now, we will use the "tabular" format and pipe relational data to the <code>relpipe-out-tabular</code>.
		</p>
		
		<m:pre jazyk="bash"><![CDATA[relpipe-in-cli generate "relation_from_cli" 3 \
		"a" "integer" \
		"b" "string" \
		"c" "boolean" \
		"1" "Hello" "true" \
		"2" "World!" "false" \
	| relpipe-out-tabular]]></m:pre>
	
		<p>Output:</p>

		<pre><![CDATA[relation_from_cli:
 ╭─────────────┬────────────┬─────────────╮
 │ a (integer) │ b (string) │ c (boolean) │
 ├─────────────┼────────────┼─────────────┤
 │           1 │ Hello      │        true │
 │           2 │ World!     │       false │
 ╰─────────────┴────────────┴─────────────╯
Record count: 2
]]></pre>

		<p>
			The syntax is simple as we see above. We specify the name of the relation, number of attributes,
			and then their definitions (names and types),
			followed by the data.
		</p>

		<p>
			A single stream may contain multiple relations:
		</p>		
		
		<m:pre jazyk="bash"><![CDATA[(relpipe-in-cli generate a 1 x string hello; \
 relpipe-in-cli generate b 1 y string world) \
	| relpipe-out-tabular]]></m:pre>
			
		<p>
			Thus we can combine various commands or files and pass the result to a single relational output filter (<code>relpipe-out-tabular</code> in this case) and get:
		</p>
		
		<pre><![CDATA[a:
 ╭────────────╮
 │ x (string) │
 ├────────────┤
 │ hello      │
 ╰────────────╯
Record count: 1
b:
 ╭────────────╮
 │ y (string) │
 ├────────────┤
 │ world      │
 ╰────────────╯
Record count: 1]]></pre>
		
	</text>

</stránka>