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Conditional Functions

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Conditional Functions

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Functions that return one of their arguments by evaluating in an if-else manner.

`COALESCE`

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Synopsis:

COALESCE(
    expression, 
    expression, 
    ...)

Input:

	1st expression
	2nd expression

…

Nth expression

COALESCE can take an arbitrary number of arguments.

Output: one of the expressions or null

DescriptionReturns the first of its arguments that is not null. If all arguments are null, then it returns null.

SELECT COALESCE(null, 'elastic', 'search') AS "coalesce";

    coalesce
---------------
elastic

SELECT COALESCE(null, null, null, null) AS "coalesce";

    coalesce
---------------
null

`GREATEST`

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Synopsis:

GREATEST(
    expression, 
    expression, 
    ...)

Input:

	1st expression
	2nd expression

…

Nth 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

DescriptionReturns the argument that has the largest value which is not null. If all arguments are null, then it returns null.

SELECT GREATEST(null, 1, 2) AS "greatest";

    greatest
---------------
2

SELECT GREATEST(null, null, null, null) AS "greatest";

    greatest
---------------
null

`IFNULL`

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Synopsis:

IFNULL(
    expression, 
    expression)

Input:

	1st expression
	2nd expression

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

DescriptionVariant of COALESCE with only two arguments. Returns the first of its arguments that is not null. If all arguments are null, then it returns null.

SELECT IFNULL('elastic', null) AS "ifnull";

    ifnull
---------------
elastic

SELECT IFNULL(null, 'search') AS "ifnull";

    ifnull
---------------
search

`ISNULL`

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Synopsis:

ISNULL(
    expression, 
    expression)

Input:

	1st expression
	2nd expression

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

DescriptionVariant of COALESCE with only two arguments. Returns the first of its arguments that is not null. If all arguments are null, then it returns null.

SELECT ISNULL('elastic', null) AS "isnull";

    isnull
---------------
elastic

SELECT ISNULL(null, 'search') AS "isnull";

    isnull
---------------
search

`LEAST`

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Synopsis:

LEAST(
    expression, 
    expression, 
    ...)

Input:

	1st expression
	2nd expression

…

Nth 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

DescriptionReturns the argument that has the smallest value which is not null. If all arguments are null, then it returns null.

SELECT LEAST(null, 2, 1) AS "least";

    least
---------------
1

SELECT LEAST(null, null, null, null) AS "least";

    least
---------------
null

`NULLIF`

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Synopsis:

NULLIF(
    expression, 
    expression)

Input:

	1st expression
	2nd expression

Output: null if the 2 expressions are equal, otherwise the 1st expression.

DescriptionReturns null when the two input expressions are equal and if not, it returns the 1st expression.

SELECT NULLIF('elastic', 'search') AS "nullif";
    nullif
---------------
elastic

SELECT NULLIF('elastic', 'elastic') AS "nullif";

    nullif:s
---------------
null

`NVL`

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Synopsis:

NVL(
    expression, 
    expression)

Input:

	1st expression
	2nd expression

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

DescriptionVariant of COALESCE with only two arguments. Returns the first of its arguments that is not null. If all arguments are null, then it returns null.

SELECT NVL('elastic', null) AS "nvl";

    nvl
---------------
elastic

SELECT NVL(null, 'search') AS "nvl";

    nvl
---------------
search

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