You can set a constant to an output column in the Expression Builder, without mapping from the input columns. As shown below, the company column of type String is set to a fixed value, Talend.
The input data will be transformed to output data after being processed into the tMap component.
The data type of the value in the Expression Builder should be consistent with the data type
of the output column. Otherwise, it will throw a Java compilation error. For example, if a
constant 1 is set for company column in the Expression Builder, it will throw a compilation
error when the Job is executed:
Type mismatch: cannot convert from int to
String, because the data type of the company column is defined as type String, but
an Integer/int value is set for this column.