问题
I'm looking to get basic metadata about the data within a database. Specifically, the number of line
elements which are surrouned by the root text
element.
Analogous to what I'd expect COUNT
to return in SQL
-- a single integer.
the database:
thufir@dur:~/flwor/group$
thufir@dur:~/flwor/group$ basex
BaseX 9.0.1 [Standalone]
Try 'help' to get more information.
>
> open people
Database 'people' was opened in 225.24 ms.
>
> xquery /
<text>
<line>people</line>
<line>joe</line>
<line>phone1</line>
<line>phone2</line>
<line>phone3</line>
<line>sue</line>
<line>cell4</line>
<line>home5</line>
<line>alice</line>
<line>atrib6</line>
<line>x7</line>
<line>y9</line>
<line>z10</line>
</text>
Query executed in 215.13 ms.
>
> exit
See you.
thufir@dur:~/flwor/group$
Counting the lines:
thufir@dur:~/flwor/group$
thufir@dur:~/flwor/group$ basex each.xq
1
2
3
4
5
6
7
8
9
10
11
12
13thufir@dur:~/flwor/group$
code:
xquery version "3.0";
for $line in db:open("people")
for $index at $count in $line/text/line
return $count
回答1:
I suppose you simply want to use count(/text/line)
.
回答2:
From Martin's answer I see it's easy from within basex itself:
thufir@dur:~/flwor/group$
thufir@dur:~/flwor/group$ basex
BaseX 9.0.1 [Standalone]
Try 'help' to get more information.
>
> open people
Database 'people' was opened in 208.33 ms.
>
> xquery /
<text>
<line>people</line>
<line>joe</line>
<line>phone1</line>
<line>phone2</line>
<line>phone3</line>
<line>sue</line>
<line>cell4</line>
<line>home5</line>
<line>alice</line>
<line>atrib6</line>
<line>x7</line>
<line>y9</line>
<line>z10</line>
</text>
Query executed in 237.69 ms.
>
> xquery count(/text/line)
13
Query executed in 20.55 ms.
>
> exit
See you.
thufir@dur:~/flwor/group$
but I was also looking to run it from an xq
file:
xquery version "3.0";
count(
for $line in db:open("people")
return $line/text/line)
来源:https://stackoverflow.com/questions/60259916/how-to-count-the-number-of-elements-in-xml