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Rules and guidelines for lookups

Use the following rules and guidelines when creating a lookup:

If the lookup is on a flat file, the file must use a comma delimiter. You cannot use any other type of delimiter.

When you configure a lookup, you can configure a simple lookup expression as part of the lookup return value. Use the $OutputField variable to represent the expression. If you use a lookup expression that does not include $OutputField, you negate the action of the lookup.

Tasks with a flat file lookup that run by a Secure Agent on Windows 7 (64 bit) might not complete. To resolve the issue, configure a network login for the Secure Agent service.

On the

Field Mapping

page, you can perform a lookup or create an expression for each source field. You cannot do both.

Each task can contain one or more lookups. To avoid impacting performance, include less than six lookups in a task.

When performing the lookup, the task performs an outerjoin and does not sort the input rows. The lookup performs a string comparison that is not case-sensitive to determine matching rows.

The source field and lookup field in the lookup condition must have compatible data types. If the data types are not compatible, the following error appears:

Source field [<source field name> (<source field data type>)] and lookup field [<lookup field name> (<lookup field data type>)] have incompatible data types.

If you create multiple lookup conditions on a lookup field and the lookup source is a flat file, all source fields must have the same data type. The

synchronization

task uses the larger precision and scale of the source field data types as the precision and scale for the target field. If the source fields do not have the same data type, the following error appears:

Lookup field <field name> in <file name> has conflict data types inferenced: <data type 1> and <data type 2>.

You cannot include lookup fields of particular data types in a lookup condition. When the lookup field in a flat file has the Text or Ntext data type or the target field of a lookup has the Text or Ntext data type, the task fails.

If you run a task with a lookup and the source field, lookup field, or output field of the lookup no longer exist in the lookup object, an error appears.

Field mappings

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