head

Return a set number of rows from the top of the data extract.

Introduction

Use the head instruction to return a set number of rows from the top of the data extract. All other rows are removed from the data extract. This is the opposite of the tail transformation.

Creating a custom script transformation using the head instruction

To create and configure a custom script using the head instruction, follow these steps:

1. Create a custom script transformation.

2. In the Instructions step, select the head instruction.

3. To configure the custom script instruction, fill in the following fields. Required fields are marked with an asterisk (*).

N*

Enter the number of rows to be returned from the top of the data extract.

Subtable

Enter the name for a subtable that you want to use within this custom script.

A subtable is a temporary table that only exists for this custom script. You can apply additional instructions within the same custom script to the subtable. However, the subtable cannot be used in any other custom scripts.

If a subtable does not exist for the current custom script, the transformation is applied to the data extract, and the enriched data is output into the subtable. If the subtable already exists for the custom script, the subtable is used as the input for the transformation and optionally as the output.

Example

Transformation configuration

N*

3

Data table before transformation

Row Number	Campaign	Account IDs
1	Aerified	377303400
2	Kanlam	634282082
3	Y-find	439889356
4	Stringtough	515023082
5	Rank	796714697
6	Tampflex	698305305
7	Holdlamis	604447800

Data table after transformation

Row Number	Campaign	Account IDs
1	Aerified	377303400
2	Kanlam	634282082
3	Y-find	439889356