Create a data extension in Salesforce Marketing Cloud
To open the list of data extensions, navigate to Subscribers > Data Extensions.
Click Create. The "Create Data Extension" dialog box will open. You can specify how you will build your data extension:
Standard Data Extension: Creates a brand new data extension with custom fields
Filtered Data Extension: Uses a source data extension and filters data for use in a new data extension
Random Data Extension: Lets you randomly select subscribers from a source data extension
Name the data extension and add a description if desired. Do not enter an external key; Marketing Cloud will generate one upon creation.
Select where you want to save your data extension. Check Sendable and Testable as applicable.
For "Retention Setting", select Off or On as desired:
Off: Data extension data will be kept indefinitely, but will be deleted in six (6) months if the extension has not been used
On: Lets you choose when the data will be deleted
Under "Fields", add fields to the data extension. Complete the information for each field you need:
Name: The name of the column
Data Type: The data type of the contents of the field. Values are the following:
Text: Letters, numbers, and spaces (this is the simplest option)
Number: An integer, no decimals
Date: A date value
Boolean: A 0 or 1 value
Email Address: An email address; a field of this type must exist before you can send email to a data extension
Phone: A phone number; this data type accepts any string with 10 or 11 digits and strips out non-digit characters
Decimal: A number with a decimal point
Length: Maximum number of characters (including spaces) you can import into this column
Primary Key: If selected, the system requires that the value in this field be unique so it can use this field to uniquely identify a row. In most cases this is the subscriber key, which is always unique.
Nullable: Determines whether this column can be empty. If you do not select this and you try to import a NULL value for this column, the system will respond as you specify in the "Skip Rows with Bad Data" field on the import definition.
Complete the "Send Relationship" field. This determines the field in the data extension that relates to the "Subscriber" table, typically the subscriber key.
If you marked your data extension to be Sendable, which means you are planning to send an email to this data extension, then each contact must also be in a list with the same subscriber key. If not, the system will not send to those contacts in your data extension.