This is a working script, assuming that the query is correct and will return values, there is no reason this code should not work.
Something to look out for, if the database which contains the table of interest is not the default database of the project then you must supply the database connection in the call to runQuery or runPrepQuery.
#filter the property change so that code is only executed when the date property changes
if event.propertyName == date:
#specify the query to run representing parameter values with the '?' character
query = 'Select t_stamp,Coordinator FROM SQDCME.dbo.SQDCME where t_stamp = ?'
#use the newValue of the date as the value to substitute into the query
args = [event.newValue]
#run the query
results = system.db.runPrepQuery(query,args)
#set the table's dataset equal to the results of the query. NOTE: system.db.runPrepQuery
#returns a pyDataSet and the table.data property is a Dataset type so use
#system.dataset.toDataSet to convert the results from a pyDataSet to a DataSet type
event.source.parent.getComponent('CoordinatorTable').data = system.dataset.toDataSet(results)
Also note that if this is the only function your wanting to perform in the propertyChange event, probably the easier (some would argue better) way to accomplish this is to use an SQL Query binding on the data property of the table and reference the popup calendar component’s date property there.