Here we are focusing on Save the WFFM Data to the Sql server.
After installing the WFFM package in sitecore,Create the database,adding connection string name "wffm",
1) update the formsDataProvider setting to sqlFormsProvider in the sitecore.wffm.Dependencies.config under the AppConfig folder.
2) Make sure your connection string name matches the above connection string name connectionstrings.config
3) Make sure the connection string name is same as above name "wffm" in sitecore.forms.config
4) make sure the check box "Save Form data to storage" checked on the form.
5) Submit the form you will see the data in the sql server db mentioned in connection string.
you will see the data in the Two tables:1) FormData, 2)FieldData.