OpenSearch/docs/reference/sql/functions/conditional.asciidoc
Costin Leau 61f49af497 SQL: Spec tests now use classpath discovery (#40388)
To avoid having to specify each spec by hand (which can miss specs to be
added), the test infrastructure now performs classpath discovery so that
each spec added, is automatically considered.

Relates #40358

(cherry picked from commit d0f60b4425c731509aa8ca765d55f563f866ef90)
2019-03-25 15:22:52 +02:00

277 lines
5.0 KiB
Plaintext

[role="xpack"]
[testenv="basic"]
[[sql-functions-conditional]]
=== Conditional Functions
Functions that return one of their arguments by evaluating in an if-else manner.
[[sql-functions-conditional-coalesce]]
==== `COALESCE`
.Synopsis:
[source, sql]
----
COALESCE(expression<1>, expression<2>, ...)
----
*Input*:
<1> 1st expression
<2> 2nd expression
...
**N**th expression
COALESCE can take an arbitrary number of arguments.
*Output*: one of the expressions or `null`
.Description
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/docs.csv-spec[coalesceReturnNonNull]
----
["source","sql",subs="attributes,callouts,macros"]
----
include-tagged::{sql-specs}/docs/docs.csv-spec[coalesceReturnNull]
----
[[sql-functions-conditional-ifnull]]
==== `IFNULL`
.Synopsis:
[source, sql]
----
IFNULL(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/docs.csv-spec[ifNullReturnFirst]
----
["source","sql",subs="attributes,callouts,macros"]
----
include-tagged::{sql-specs}/docs/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/docs.csv-spec[isNullReturnFirst]
----
["source","sql",subs="attributes,callouts,macros"]
----
include-tagged::{sql-specs}/docs/docs.csv-spec[isNullReturnSecond]
----
[[sql-functions-conditional-nvl]]
==== `NVL`
.Synopsis:
[source, sql]
----
NVL(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/docs.csv-spec[nvlReturnFirst]
----
["source","sql",subs="attributes,callouts,macros"]
----
include-tagged::{sql-specs}/docs/docs.csv-spec[nvlReturnSecond]
----
[[sql-functions-conditional-nullif]]
==== `NULLIF`
.Synopsis:
[source, sql]
----
NULLIF(expression<1>, expression<2>)
----
*Input*:
<1> 1st expression
<2> 2nd expression
*Output*: `null` if the 2 expressions are equal, otherwise the 1st expression.
.Description
Returns `null` when the two input expressions are equal and
if not, it returns the 1st expression.
["source","sql",subs="attributes,callouts,macros"]
----
include-tagged::{sql-specs}/docs/docs.csv-spec[nullIfReturnFirst]
----
["source","sql",subs="attributes,callouts,macros"]
----
include-tagged::{sql-specs}/docs/docs.csv-spec[nullIfReturnNull]
----
[[sql-functions-conditional-greatest]]
==== `GREATEST`
.Synopsis:
[source, sql]
----
GREATEST(expression<1>, expression<2>, ...)
----
*Input*:
<1> 1st expression
<2> 2nd expression
...
**N**th expression
GREATEST can take an arbitrary number of arguments and
all of them must be of the same data type.
*Output*: one of the expressions or `null`
.Description
Returns the argument that has the largest value which is not null.
If all arguments are null, then it returns `null`.
["source","sql",subs="attributes,callouts,macros"]
----
include-tagged::{sql-specs}/docs/docs.csv-spec[greatestReturnNonNull]
----
["source","sql",subs="attributes,callouts,macros"]
----
include-tagged::{sql-specs}/docs/docs.csv-spec[greatestReturnNull]
----
[[sql-functions-conditional-least]]
==== `LEAST`
.Synopsis:
[source, sql]
----
LEAST(expression<1>, expression<2>, ...)
----
*Input*:
<1> 1st expression
<2> 2nd expression
...
**N**th expression
LEAST can take an arbitrary number of arguments and
all of them must be of the same data type.
*Output*: one of the expressions or `null`
.Description
Returns the argument that has the smallest value which is not null.
If all arguments are null, then it returns `null`.
["source","sql",subs="attributes,callouts,macros"]
----
include-tagged::{sql-specs}/docs/docs.csv-spec[leastReturnNonNull]
----
["source","sql",subs="attributes,callouts,macros"]
----
include-tagged::{sql-specs}/docs/docs.csv-spec[leastReturnNull]
----