Postgres - > [22007]错误：类型时间戳的输入语法无效：“”

I have a table that stores a number of data types as a string. Sometimes this value is a string representing a timestamp. The following query is meant to join the RetsEntry and RetsProvider tables on a fieldname (specified in RetsProvider) then filter out the "systemid" column values where the timestamp of the entry is between two times.I have a table that stores a number of data typ