For those source datatypes that are captured or copied as strings, a Connect CDC Kernel component formats the values for delivery to the target DBMS. The string data, if reformatted, is processed by the Expression Handler component. The format of the data in the input string to the Expression Handler and the format of the data in the output string varies with the source and target DBMS datatypes respectively. The information in the table in Formats for source and target data is particularly useful if you are defining your own expression method.
When writing your own expression methods, you must ensure that your method returns character data in the format that can be inserted successfully into the target columns. Potentially your methods could change the format of the captured data. You must take into consideration the general rules discussed in Data handling, and you must follow the string formatting rules that are described in Formats for source and target data .