Transformations

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Sequence output fields

The Sequence transformation has two output fields, NEXTVAL and CURRVAL. In SQL ELT mode, the transformation has one output field, NEXTVAL. You can't edit or delete these fields.

You can connect a Sequence transformation to any transformation. If the mapping contains both fields, you don't need to map both of the output fields. If you don't map one of the output fields, the

mapping

task ignores the unmapped field.

In mappings in SQL ELT mode, you can only connect a Sequence transformation directly to a downstream Expression transformation or target.

NEXTVAL field

Use the NEXTVAL field to generate a sequence of numbers based on the Initial Value and Increment By properties.

Map the NEXTVAL field to an input field in a Target transformation or other downstream transformation to generate a sequence of numbers. If you don't configure the Sequence transformation to cycle through the sequence, the NEXTVAL field generates sequence numbers up to the configured End Value.

If you map the NEXTVAL field to multiple transformations, the

mapping

task generates the same sequence or a unique sequence of numbers for each downstream transformation based on the mapping type and whether incoming fields are disabled.

The following table lists the situations where the Sequence transformation generates the same sequence or a unique sequence of numbers:

Mapping type	Incoming fields are...	Same sequence or unique sequence?
Mapping	Not disabled	Same sequence
Mapping	Disabled	Unique sequence*
Mapping (SQL ELT mode)	-	Same sequence
* To generate the same sequence of numbers when incoming fields are disabled, you can place an Expression transformation between the Sequence transformation and its downstream transformations to stage the sequence of numbers.

CURRVAL field

The CURRVAL field value is the NEXTVAL value plus the Increment By value. For example, if the Initial Value is 1 and Increment By is 1, the

mapping

task generates the following values for NEXTVAL and CURRVAL:

NEXTVAL	CURRVAL
1	2
2	3
3	4
4	5
5	6

Typically, you map the CURRVAL field when the NEXTVAL field is already mapped to a downstream transformation in the map. If you map the CURRVAL field without mapping the NEXTVAL field, the

mapping

task generates the same number for each row.

Sequence transformation

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