...

if(x.resultSet[0].contactemailaddr) 
     vendorEmail.value = x.resultSet[0].contactemailaddr;
else
     vendorEmail.value = null;

Conditional NULL in MySQL Insert Statement

If you are using the MySQL database, there is a special syntax to insert a conditional null in an insert statement. For Example, let's say your form/flow has an optional date field in a form that is designed to insert a row into the database. The insert will fail because the database connector inserts an empty string where MySQL expects NULL.

...

In this example, {optional_date} refers to a column of type date and is optional. When its empty in your form, NULL is inserted fulfilling the MySQL requirement otherwise the value in the field will be inserted.

Empty resultsets

If the results of a query are empty, the Database Connector returns an empty HTTP response. This is because the attribute emptyStringForEmptyResultSet="true" is configured by default. You may notice the error message below in the debug console when testing your forms if no rows are returned by a query.

...