Database Reference
In-Depth Information
Table 16-5. Pig Latin expressions
Category
Expressions
Description
Examples
Constant
Literal
Constant value (see also the “Literal
example” column in
Table 16-6
)
1.0
,
'a'
Field (by posi-
tion)
Field in position
n
(zero-based)
$
n
$0
Field (by
name)
Field named
f
year
f
Field (disam-
biguate)
Field named
f
from relation
r
after
grouping or joining
r
::
f
A::year
Projection
c
.$
n
,
c
.
f
Field in container
c
(relation, bag, or
tuple) by position, by name
records.$0
,
records.year
Map lookup
Value associated with key
k
in map
m
m
#
k
items#'Coat'
Cast
Cast of field
f
to type
t
(
t
)
f
(int) year
Arithmetic
x
+
y
,
x
-
y
Addition, subtraction
$1 + $2
,
$1 - $2
x
*
y
,
x
/
y
Multiplication, division
$1 * $2
,
$1 / $2
Modulo, the remainder of
x
divided by
y
x
%
y
$1 % $2
+
x
,
-
x
Unary positive, negation
+1
,
-1
Conditional
Bincond/ternary;
y
if
x
evaluates to
true,
z
otherwise
x
?
y
:
z
quality == 0 ? 0 : 1
Multi-case conditional
CASE
CASE q WHEN 0 THEN
'good' ELSE 'bad' END
Comparison
x
==
y
,
x
!=
y
Equals, does not equal
quality == 0
,
temperat-
ure != 9999
x
>
y
,
x
<
y
Greater than, less than
quality > 0
,
quality <
10
x
>=
y
,
x
<=
y
Greater than or equal to, less than or
equal to
quality >= 1
,
quality <=
9
x
matches
y
Pattern matching with regular expres-
sion
quality matches
'[01459]'
Is
null
x
is null
temperature is null
Is not
null
x
is not
null
temperature is not
null
