FirstChild (MDX)

Returns the first child of the member.

It is equivalent to children(0).

Query

[Time].[Calendar].[2010].FirstChild

Result

{ 
  [Time].[Calendar].[Quarter].[Q1 2010]
}

Assertion : MDX Equals

[Time].[Calendar].[2010].children(0)

Assertion : MDX Equals

Head([Time].[Calendar].[2010].Children)

Returns NULL if applied to a leaf member (i.e., member without children).

Query

[Geography].[Geo].[Paris].FirstChild

Result

NULL

Returns NULL if applied to a NULL entity.

Query

NULL.FirstChild

Result

NULL

Using invalid parameter type causes an error.

Query

([Geography].[Geo].[Spain],[Product].[Licence].[Personal]).FirstChild

Result

Error Code    : OLAP_FUNCTION_ARGUMENT_TYPE_MISMATCH
Error Message : FirstChild() : argument (0) type mismatch: expected:'member', got:'tuple'

Using invalid parameter type causes an error.

Query

[Geography].[Geo].[Continent].FirstChild

Result

Error Code    : OLAP_FUNCTION_ARGUMENT_TYPE_MISMATCH
Error Message : FirstChild() : argument (0) type mismatch: expected:'member', got:'level'

Using invalid parameter type causes an error.

Query

{[Geography].[Geo].[United States],[Geography].[Geo].[Switzerland],[Geography].[Geo].[Spain]}.FirstChild

Result

Error Code    : OLAP_FUNCTION_ARGUMENT_TYPE_MISMATCH
Error Message : FirstChild() : argument (0) type mismatch: expected:'member', got:'set'

Using invalid parameter type causes an error.

Query

{([Geography].[Geo].[United States],[Product].[Licence].[Personal]),([Geography].[Geo].[Spain],[Product].[Licence].[Personal])}.FirstChild

Result

Error Code    : OLAP_FUNCTION_ARGUMENT_TYPE_MISMATCH
Error Message : FirstChild() : argument (0) type mismatch: expected:'member', got:'set'

Using invalid parameter type causes an error.

Query

"hello".FirstChild

Result

Error Code    : OLAP_FUNCTION_ARGUMENT_TYPE_MISMATCH
Error Message : FirstChild() : argument (0) type mismatch: expected:'member', got:'string'