isNull
from employees
| where gender is null
| sort first_name
| keep first_name, gender
| limit 3;

first_name:keyword|gender:keyword
Berni             |null
Cristinel         |null
Duangkaew         |null
;

notIsNull
from employees
| where gender is not null
| sort first_name
| keep first_name, gender
| limit 3;

first_name:keyword|gender:keyword
Alejandro         |F
Amabile           |M
Anneke            |F
;

isNullForDocs
// tag::is-null[]
FROM employees
| WHERE birth_date IS NULL
// end::is-null[]
| KEEP first_name, last_name
| SORT first_name
| LIMIT 3
;

// tag::is-null-result[]
first_name:keyword|last_name:keyword   
Basil             |Tramer         
Florian           |Syrotiuk       
Lucien            |Rosenbaum
// end::is-null-result[]
;

isNotNullForDocs
// tag::is-not-null[]
FROM employees
| WHERE is_rehired IS NOT NULL
| STATS COUNT(emp_no)
// end::is-not-null[]
;

// tag::is-not-null-result[]
COUNT(emp_no):long 
84
// end::is-not-null-result[]
;

coalesceSimple#[skip:-8.12.99,reason:expression spaces are maintained since 8.13]
// tag::coalesce[]
ROW a=null, b="b"
| EVAL COALESCE(a, b)
// end::coalesce[]
;

// tag::coalesce-result[]
a:null | b:keyword | COALESCE(a, b):keyword
  null |         b | b
// end::coalesce-result[]
;

coalesce
FROM employees
| EVAL first_name = COALESCE(first_name, "X")
| SORT first_name DESC, emp_no ASC
| KEEP emp_no, first_name
| limit 10;

emp_no:integer | first_name:keyword
         10047 | Zvonko
         10081 | Zhongwei
         10026 | Yongqiao
         10043 | Yishay
         10050 | Yinghua
         10087 | Xinglin
         10030 | X
         10031 | X
         10032 | X
         10033 | X
;

coalesceOnce
ROW a=1 | EVAL a = COALESCE(a);

a:integer
        1
;

coalesceBackwards
FROM employees
| EVAL first_name = COALESCE("X", first_name)
| SORT first_name DESC, emp_no ASC
| KEEP emp_no, first_name
| limit 10;

emp_no:integer | first_name:keyword
         10001 | X
         10002 | X
         10003 | X
         10004 | X
         10005 | X
         10006 | X
         10007 | X
         10008 | X
         10009 | X
         10010 | X
;

coalesceEndsInNull
# ending in null is sill because it'll noop but it shouldn't break things.
FROM employees
| EVAL first_name = COALESCE(first_name, last_name, null)
| SORT first_name DESC, emp_no ASC
| KEEP emp_no, first_name
| limit 3;

emp_no:integer | first_name:keyword
         10047 | Zvonko
         10081 | Zhongwei
         10026 | Yongqiao
;

coalesceFolding
FROM employees
| EVAL foo=COALESCE(true, false, null)
| SORT emp_no ASC
| KEEP emp_no, first_name, foo
| limit 3;

emp_no:integer | first_name:keyword | foo:boolean
         10001 | Georgi             | true
         10002 | Bezalel            | true
         10003 | Parto              | true
;

coalesceMixedNumeric
required_capability: mixed_numeric_types_in_coalesce
FROM employees
| WHERE emp_no <= 10021 and emp_no >= 10018
| EVAL x = coalesce(languages.long, 0), y = coalesce(height, 0), z = coalesce(languages::double, 0)
| SORT emp_no ASC
| KEEP emp_no, languages, x, height, y, z
;

emp_no:integer | languages:integer | x:long | height:double | y:double | z:double
         10018 | 2                 | 2      | 1.97          | 1.97     | 2.0
         10019 | 1                 | 1      | 2.06          | 2.06     | 1.0
         10020 | null              | 0      | 1.41          | 1.41     | 0.0
         10021 | null              | 0      | 1.47          | 1.47     | 0.0
;

coalesceMixedNumericWithNull
required_capability: mixed_numeric_types_in_coalesce
FROM employees
| WHERE emp_no <= 10021 and emp_no >= 10018
| EVAL x = coalesce(languages.long, null, 0), y = coalesce(null, height, 0),  z = coalesce(languages::double, null, 0)
| SORT emp_no ASC
| KEEP emp_no, languages.long, x, height, y, z
;

emp_no:integer | languages.long:long | x:long | height:double | y:double | z:double
         10018 | 2                   | 2      | 1.97          | 1.97     | 2.0
         10019 | 1                   | 1      | 2.06          | 2.06     | 1.0
         10020 | null                | 0      | 1.41          | 1.41     | 0.0
         10021 | null                | 0      | 1.47          | 1.47     | 0.0
;

coalesceMixedNumericFields
required_capability: mixed_numeric_types_in_coalesce
FROM employees
| WHERE emp_no <= 10021 and emp_no >= 10018
| EVAL x = coalesce(height, languages.long, 0), y = coalesce(height, null, languages, 0),
z = coalesce(languages::double, null, salary, height, 0)
| SORT emp_no ASC
| KEEP emp_no, languages, height, x, y, z, salary
;

emp_no:integer | languages:integer | height:double | x:double | y:double | z:double | salary:integer
         10018 | 2                 | 1.97          | 1.97     | 1.97     | 2.0      | 56760
         10019 | 1                 | 2.06          | 2.06     | 2.06     | 1.0      | 73717
         10020 | null              | 1.41          | 1.41     | 1.41     | 40031.0  | 40031
         10021 | null              | 1.47          | 1.47     | 1.47     | 60408.0  | 60408
;

whereNull
FROM employees
| WHERE NULL and emp_no <= 10021
| SORT first_name, last_name
| EVAL fullname = CONCAT(first_name, " ", last_name)
| KEEP fullname, job_positions, salary, salary_change
| limit 5
;

fullname:keyword | job_positions:keyword | salary:integer | salary_change:double
;

inConvertedNull
required_capability: filter_in_converted_null
FROM employees
| WHERE emp_no in (10021, 10022, null::int)
| KEEP emp_no, first_name, last_name
| SORT emp_no
;

emp_no:integer | first_name:keyword | last_name:keyword   
10021          | Ramzi              | Erde
10022          | Shahaf             | Famili
;