Use a duplicate check rule to check if the data doesn't already exist in the table.

Before you can set up a duplicate check rule, set up the duplicate check to be applied. A duplicate check defines which combination of table fields is checked on duplicate values. So, the combination of field values must be unique in the table.

Standard procedure

1.	Click Data quality management.
2.	On the Data quality policies tab, in the list, click the link of the desired data quality policy.
3.	Click the Duplicate check rules tab.
	Note: If you want to edit another data quality policy version than the currently shown version, first select the desired version. To do so, on the Action Pane, on the Version tab, click Versions. On the dialog, select the desired version and click OK.
4.	Click Add.
5.	In the Duplicate check field, enter or select a duplicate check.
6.	Define what is done if a duplicate value exists: - Warning: A warning message is shown. The record or the field value is saved. - Error: An error message is shown. The record or the field value is not saved.
	In the Warning/Error field, select an option.
7.	Close the page.