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SQL: Implement IIF(<cond>, <result1>, <result2>) (#41420)
Implement a more trivial case of the CASE expression which is expressed as a traditional function with 2 or 3 arguments. e.g.: IIF(a = 1, 'one', 'many') IIF(a > 0, 'positive') Closes: #40917
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‎docs/reference/sql/functions/conditional.asciidoc‎

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@@ -223,6 +223,52 @@ include-tagged::{sql-specs}/docs/docs.csv-spec[ifNullReturnFirst]
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include-tagged::{sql-specs}/docs/docs.csv-spec[ifNullReturnSecond]
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----
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[[sql-functions-conditional-iif]]
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==== `IFF`
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.Synopsis:
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[source, sql]
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----
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IIF(expression<1>, expression<2>, [expression<3>])
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----
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*Input*:
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<1> boolean condition to check
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<2> return value if the boolean condition evaluates to `true`
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<3> return value if the boolean condition evaluates `false`; optional
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*Output*: 2nd expression if 1st expression (condition) evaluates to `true`. If it evaluates to `false`
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return 3rd expression. If 3rd expression is not provided return `null`.
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.Description
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Conditional function that implements the standard _IF <condition> THEN <result1> ELSE <result2>_
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logic of programming languages. If the 3rd expression is not provided and the condition evaluates to `false`,
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`null` is returned.
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["source","sql",subs="attributes,callouts,macros"]
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----
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include-tagged::{sql-specs}/docs/docs.csv-spec[iifWithDefaultValue]
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----
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["source","sql",subs="attributes,callouts,macros"]
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----
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include-tagged::{sql-specs}/docs/docs.csv-spec[iifWithoutDefaultValue]
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----
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[TIP]
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=================
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*IIF* functions can be combined to implement more complex logic simulating the <<sql-functions-conditional-case>>
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expression. E.g.:
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[source, sql]
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IIF(a = 1, 'one', IIF(a = 2, 'two', IIF(a = 3, 'three', 'many')))
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=================
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[[sql-functions-conditional-isnull]]
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==== `ISNULL`

‎docs/reference/sql/functions/index.asciidoc‎

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@@ -131,6 +131,7 @@
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** <<sql-functions-conditional-coalesce>>
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** <<sql-functions-conditional-greatest>>
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** <<sql-functions-conditional-ifnull>>
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** <<sql-functions-conditional-iif>>
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** <<sql-functions-conditional-isnull>>
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** <<sql-functions-conditional-least>>
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** <<sql-functions-conditional-nullif>>

‎x-pack/plugin/sql/qa/src/main/resources/command.csv-spec‎

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@@ -29,6 +29,7 @@ CASE |CONDITIONAL
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COALESCE |CONDITIONAL
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GREATEST |CONDITIONAL
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IFNULL |CONDITIONAL
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IIF |CONDITIONAL
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ISNULL |CONDITIONAL
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LEAST |CONDITIONAL
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NULLIF |CONDITIONAL

‎x-pack/plugin/sql/qa/src/main/resources/conditionals.csv-spec‎

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@@ -179,3 +179,142 @@ count | gender | languages
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11 | M | 3
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11 | M | 4
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;
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iifField
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SELECT emp_no, IIF(emp_no - 10000 < 10, 'First 10', 'Second 10') as "iif_result" FROM test_emp WHERE emp_no >= 10005
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ORDER BY emp_no LIMIT 10;
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emp_no | iif_result
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--------+-----------
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10005 | First 10
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10006 | First 10
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10007 | First 10
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10008 | First 10
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10009 | First 10
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10010 | Second 10
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10011 | Second 10
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10012 | Second 10
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10013 | Second 10
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10014 | Second 10
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;
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iifFieldWithoutAlias
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SELECT emp_no, IIF(emp_no - 10000 < 10, emp_no, emp_no % 10) FROM test_emp WHERE emp_no >= 10005
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ORDER BY emp_no LIMIT 10;
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emp_no | IIF(emp_no - 10000 < 10, emp_no, emp_no % 10)
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--------+----------------------------------------------
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10005 | 10005
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10006 | 10006
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10007 | 10007
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10008 | 10008
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10009 | 10009
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10010 | 0
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10011 | 1
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10012 | 2
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10013 | 3
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10014 | 4
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;
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iifFieldNoElse
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SELECT emp_no, IIF(emp_no - 10000 < 10, 'First 10') as "iif_result" FROM test_emp WHERE emp_no >= 10005
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ORDER BY emp_no LIMIT 10;
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emp_no | iif_result
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--------+----------
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10005 | First 10
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10006 | First 10
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10007 | First 10
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10008 | First 10
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10009 | First 10
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10010 | null
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10011 | null
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10012 | null
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10013 | null
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10014 | null
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;
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iifWhere
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SELECT last_name FROM test_emp WHERE IIF(LENGTH(last_name) < 7, 'ShortName') IS NOT NULL ORDER BY emp_no LIMIT 10;
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last_name
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-----------
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Simmel
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Peac
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Sluis
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Terkki
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Genin
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Peha
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Erde
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Famili
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Pettey
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Heyers
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;
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iifOrderBy
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SELECT last_name FROM test_emp ORDER BY IIF(languages >= 3, 'first', 'second'), emp_no LIMIT 10;
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last_name
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-----------
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Simmel
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Bamford
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Koblick
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Preusig
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Zielinski
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Piveteau
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Sluis
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Bridgland
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Genin
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Nooteboom
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;
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iifGroupBy
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schema::count:l|lang_skills:s
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SELECT count(*) AS count, IIF(NVL(languages, 0) <= 1 , 'zero-to-one', 'multilingual') as lang_skills FROM test_emp
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GROUP BY lang_skills ORDER BY 2;
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count | lang_skills
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---------------+---------------
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75 |multilingual
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25 |zero-to-one
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;
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iifGroupByComplexNested
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schema::count:l|lang_skills:s
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SELECT count(*) AS count,
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IIF(NVL(languages, 0) = 0, 'zero',
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IIF(languages = 1, 'one',
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IIF(languages = 2, 'bilingual',
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IIF(languages = 3, 'trilingual', 'multilingual')))) as lang_skills FROM test_emp GROUP BY lang_skills ORDER BY 2;
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count | lang_skills
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---------------+---------------
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19 |bilingual
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39 |multilingual
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15 |one
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17 |trilingual
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10 |zero
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;
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iifGroupByAndHaving
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schema::count:l|gender:s|languages:byte
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SELECT count(*) AS count, gender, languages FROM test_emp
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GROUP BY 2, 3 HAVING IIF(count(*) > 10, 'many', 'a few') = 'many'
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ORDER BY 2, 3;
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count | gender | languages
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---------------+---------------+---------------
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11 |M |2
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11 |M |3
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11 |M |4
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;
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iifWithConvertAndGroupBy
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SELECT CONVERT(IIF(languages > 1, IIF(languages = 3, '3')), SQL_BIGINT) AS cond FROM test_emp GROUP BY cond ORDER BY cond DESC;
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cond:l
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-------
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3
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null
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;

‎x-pack/plugin/sql/qa/src/main/resources/docs/docs.csv-spec‎

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@@ -206,6 +206,7 @@ CASE |CONDITIONAL
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COALESCE |CONDITIONAL
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GREATEST |CONDITIONAL
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IFNULL |CONDITIONAL
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IIF |CONDITIONAL
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ISNULL |CONDITIONAL
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LEAST |CONDITIONAL
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NULLIF |CONDITIONAL
@@ -2095,6 +2096,29 @@ elastic
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;
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iifWithDefaultValue
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schema::result1:s|result2:s
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// tag::iifWithDefaultValue
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SELECT IIF(1 < 2, 'TRUE', 'FALSE') AS result1, IIF(1 > 2, 'TRUE', 'FALSE') AS result2;
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result1 | result2
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---------------+---------------
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TRUE |FALSE
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// end::iifWithDefaultValue
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;
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iifWithoutDefaultValue
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schema::result1:s|result2:s
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// tag::iifWithoutDefaultValue
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SELECT IIF(1 < 2, 'TRUE') AS result1, IIF(1 > 2 , 'TRUE') AS result2;
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result1 | result2
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---------------+---------------
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TRUE |null
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// end::iifWithoutDefaultValue
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;
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ifNullReturnSecond
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// tag::ifNullReturnSecond
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SELECT IFNULL(null, 'search') AS "ifnull";

‎x-pack/plugin/sql/src/main/java/org/elasticsearch/xpack/sql/expression/function/FunctionRegistry.java‎

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import org.elasticsearch.xpack.sql.expression.predicate.conditional.Case;
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import org.elasticsearch.xpack.sql.expression.predicate.conditional.Coalesce;
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import org.elasticsearch.xpack.sql.expression.predicate.conditional.Greatest;
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import org.elasticsearch.xpack.sql.expression.predicate.conditional.Iif;
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import org.elasticsearch.xpack.sql.expression.predicate.conditional.IfNull;
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import org.elasticsearch.xpack.sql.expression.predicate.conditional.Least;
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import org.elasticsearch.xpack.sql.expression.predicate.conditional.NullIf;
@@ -172,6 +173,7 @@ private void defineDefaultFunctions() {
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// Conditional
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addToMap(def(Case.class, Case::new, "CASE"),
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def(Coalesce.class, Coalesce::new, "COALESCE"),
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def(Iif.class, Iif::new, "IIF"),
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def(IfNull.class, IfNull::new, "IFNULL", "ISNULL", "NVL"),
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def(NullIf.class, NullIf::new, "NULLIF"),
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def(Greatest.class, Greatest::new, "GREATEST"),
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static <T extends Function> FunctionDefinition def(Class<T> function,
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ThreeParametersFunctionBuilder<T> ctorRef, String... names) {
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FunctionBuilder builder = (source, children, distinct, cfg) -> {
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boolean isLocateFunction = function.isAssignableFrom(Locate.class);
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if (isLocateFunction && (children.size() > 3 || children.size() < 2)) {
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boolean hasMinimumTwo = function.isAssignableFrom(Locate.class) || function.isAssignableFrom(Iif.class);
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if (hasMinimumTwo && (children.size() > 3 || children.size() < 2)) {
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throw new SqlIllegalArgumentException("expects two or three arguments");
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} else if (!isLocateFunction && children.size() != 3) {
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} else if (!hasMinimumTwo && children.size() != 3) {
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throw new SqlIllegalArgumentException("expects exactly three arguments");
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}
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if (distinct) {

‎x-pack/plugin/sql/src/main/java/org/elasticsearch/xpack/sql/expression/predicate/conditional/Case.java‎

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public class Case extends ConditionalFunction {
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private final List<IfConditional> conditions;
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private final Expression defaultElse;
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private final Expression elseResult;
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@SuppressWarnings("unchecked")
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public Case(Source source, List<Expression> expressions) {
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super(source, expressions);
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this.conditions = (List<IfConditional>) (List<?>) expressions.subList(0, expressions.size() - 1);
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this.defaultElse = expressions.get(expressions.size() - 1);
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this.elseResult = expressions.get(expressions.size() - 1);
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}
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public List<IfConditional> conditions() {
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return conditions;
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}
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public Expression defaultElse() {
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return defaultElse;
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public Expression elseResult() {
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return elseResult;
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}
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5050
@Override
5151
public DataType dataType() {
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if (dataType == null) {
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if (conditions.isEmpty()) {
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dataType = defaultElse().dataType();
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dataType = elseResult().dataType();
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} else {
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dataType = DataType.NULL;
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}
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}
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if (expectedResultDataType == null) {
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expectedResultDataType = defaultElse().dataType();
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expectedResultDataType = elseResult().dataType();
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}
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for (IfConditional conditional : conditions) {
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}
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}
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if (DataTypes.areTypesCompatible(expectedResultDataType, defaultElse.dataType()) == false) {
105+
if (DataTypes.areTypesCompatible(expectedResultDataType, elseResult.dataType()) == false) {
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return new TypeResolution(format(null, "ELSE clause of [{}] must be [{}], found value [{}] type [{}]",
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defaultElse.sourceText(),
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elseResult.sourceText(),
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expectedResultDataType.typeName,
109-
Expressions.name(defaultElse),
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defaultElse.dataType().typeName));
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Expressions.name(elseResult),
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elseResult.dataType().typeName));
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}
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return TypeResolution.TYPE_RESOLVED;
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119119
*/
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@Override
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public boolean foldable() {
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return (conditions.isEmpty() && defaultElse.foldable()) ||
122+
return (conditions.isEmpty() && elseResult.foldable()) ||
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(conditions.size() == 1 && conditions.get(0).condition().foldable() && conditions.get(0).result().foldable());
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}
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if (conditions.isEmpty() == false && conditions.get(0).condition().fold() == Boolean.TRUE) {
129129
return conditions.get(0).result().fold();
130130
}
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return defaultElse.fold();
131+
return elseResult.fold();
132132
}
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134134
@Override
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138138
pipes.add(Expressions.pipe(ifConditional.condition()));
139139
pipes.add(Expressions.pipe(ifConditional.result()));
140140
}
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pipes.add(Expressions.pipe(defaultElse));
141+
pipes.add(Expressions.pipe(elseResult));
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return new CasePipe(source(), this, pipes);
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}
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149149
templates.add(asScript(ifConditional.condition()));
150150
templates.add(asScript(ifConditional.result()));
151151
}
152-
templates.add(asScript(defaultElse));
152+
templates.add(asScript(elseResult));
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154154
StringJoiner template = new StringJoiner(",", "{sql}.caseFunction([", "])");
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ParamsBuilder params = paramsBuilder();

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