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SQL: Implement ISNULL(expr1, expr2) #35793

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Merged
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Nov 21, 2018
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SQL: Implement ISNULL(expr1, expr2) #35793

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37 changes: 37 additions & 0 deletions docs/reference/sql/functions/conditional.asciidoc
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Original file line number Diff line number Diff line change
Expand Up @@ -81,3 +81,40 @@ include-tagged::{sql-specs}/docs.csv-spec[ifNullReturnFirst]
----
include-tagged::{sql-specs}/docs.csv-spec[ifNullReturnSecond]
----


[[sql-functions-conditional-isnull]]
==== `ISNULL`

.Synopsis
[source, sql]
----
ISNULL ( expression<1>, expression<2> )
----

*Input*:

<1> 1st expression

<2> 2nd expression


*Output*: 2nd expression if 1st expression is null, otherwise 1st expression.

.Description

Variant of <<sql-functions-conditional-coalesce>> with only two arguments.
Returns the first of its arguments that is not null.
If all arguments are null, then it returns `null`.



["source","sql",subs="attributes,callouts,macros"]
----
include-tagged::{sql-specs}/docs.csv-spec[isNullReturnFirst]
----

["source","sql",subs="attributes,callouts,macros"]
----
include-tagged::{sql-specs}/docs.csv-spec[isNullReturnSecond]
----
3 changes: 2 additions & 1 deletion x-pack/plugin/sql/qa/src/main/resources/command.csv-spec
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Expand Up @@ -21,7 +21,8 @@ SUM_OF_SQUARES |AGGREGATE
VAR_POP |AGGREGATE
COALESCE |CONDITIONAL
IFNULL |CONDITIONAL
DAY |SCALAR
ISNULL |CONDITIONAL
DAY |SCALAR
DAYNAME |SCALAR
DAYOFMONTH |SCALAR
DAYOFWEEK |SCALAR
Expand Down
25 changes: 24 additions & 1 deletion x-pack/plugin/sql/qa/src/main/resources/docs.csv-spec
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Expand Up @@ -198,7 +198,8 @@ SUM_OF_SQUARES |AGGREGATE
VAR_POP |AGGREGATE
COALESCE |CONDITIONAL
IFNULL |CONDITIONAL
DAY |SCALAR
ISNULL |CONDITIONAL
DAY |SCALAR
DAYNAME |SCALAR
DAYOFMONTH |SCALAR
DAYOFWEEK |SCALAR
Expand Down Expand Up @@ -1553,3 +1554,25 @@ SELECT IFNULL(null, 'search') AS "ifnull";
search
// end::ifNullReturnSecond
;


isNullReturnFirst
// tag::isNullReturnFirst
SELECT ISNULL('elastic', null) AS "isnull";

isnull
---------------
elastic
// end::isNullReturnFirst
;


isNullReturnSecond
// tag::isNullReturnSecond
SELECT ISNULL(null, 'search') AS "isnull";

isnull
---------------
search
// end::isNullReturnSecond
;
2 changes: 1 addition & 1 deletion ...n/sql/src/main/java/org/elasticsearch/xpack/sql/expression/function/FunctionRegistry.java
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Expand Up @@ -146,7 +146,7 @@ private void defineDefaultFunctions() {
// Scalar functions
// conditional
addToMap(def(Coalesce.class, Coalesce::new));
addToMap(def(IFNull.class, IFNull::new));
addToMap(def(IFNull.class, IFNull::new, "ISNULL"));
// Date
addToMap(def(DayName.class, DayName::new, "DAYNAME"),
def(DayOfMonth.class, DayOfMonth::new, "DAYOFMONTH", "DAY", "DOM"),
Expand Down