Forum Discussion
Merge Function Throwing errors if there is a NULL value
The root source of the error was burried in the left side of the left outer join, below the 999 preview rows. The problem was that I had concatenated three columns together, which included null values. If I concatenate 3 columns together with one or all three values being null then I got the error message:
Expression.Error: We cannot conver the value null to type Logical.
Details:
Value=
Type=Type
This expression error does not cause the table to fail until it is executed as part of a join, making it very hard to identify the step that caused the error.
Your frustration at this made me laugh. I know the feeling all too well! Glad you found a fix.
For anyone else who's had this problem, I've also had this error, caused by null values being fed into a conditional column. I had appended two tables. For one of the columns, Table 1 had empty cells represented as "", Table 2 had them as null. In the appended table, this column was used as a condition for a conditional column (if value), but it didn't like the null values so threw up this error. I fixed by replacing the null values in Table 2 with "".
It's unfortunate these error messages are so vague. Took a bit of trial and error to figure this one out.