The Designer performs connection validation each time you connect ports in a mapping and each time you validate or save a mapping. When you connect ports, the Designer verifies that you make valid connections. When you save or validate a mapping, the Designer verifies that the connections are valid and that all required ports are connected. When you save or validate a mapping, the Designer makes the following connection validations:
At least one source and one target must be connected.
Source qualifiers must be mapped to a target.
Mapplets must be connected.
At least one mapplet input port and output port is connected to the mapping. If the mapplet includes a source qualifier that uses an SQL override, the Designer prompts you to connect all mapplet output ports to the mapping.
Datatypes between ports must be compatible.
If you change a port datatype to one that is incompatible with the port it is connected to, the Designer generates an error and invalidates the mapping. For example, you have two Date/Time ports connected, and you change one port to a Decimal. The Designer invalidates the mapping. You can however, change the datatype if it remains compatible with the connected ports, such as Char and Varchar.