Union thinks column numbers are different

[kferrone]

I am trying to make a union between two of the same table. I am following a tutorial on how to make tables incrementally load: Incrementally Load tables.

First I import the original tables the default PowerBI way which imports every column into a table. On those tables you can right click and view the source query which I copied and pasted into a new table where I simply add a where clause to the end to narrow in on the new data.

Then I go to modeling in the ribbon and create a new table with a union like so: tbl_union = UNION('tbl_old_data','tbl_new_data').

The issue is sometimes the tables will Union together just fine, then others will complain the number of columns don't match up.
The error message: "Each table argument of 'UNION' must have the same number of columns."

Each table I did this to, I followed the same exact process. It is really weird only some tables get this error and others don't. I have a feeling the problem is due to some kind of type mismatch with a column from each table. I'm pretty sure the default import is importing some columns as a different type than when the data came from a query.

Can anyone help clarify what is wrong here?

[Anonymous]

Hi @kferrone,

If you can't ensure these columns will be changed, you can try to use SELECTCOLUMNS function to choose specific columns.

Merged Table= 
UNION(
SELECTCOLUMNS('Table1',"COLUMN1",[Column1],"COLUMN2",[Column2],...),
SELECTCOLUMNS('Table2',"COLUMN1",[Column1],"COLUMN2",[Column2],...),
SELECTCOLUMNS('Table3',"COLUMN1",[Column1],"COLUMN2",[Column2],...)
)

You can also try use Table.InsertRows(Power query) to merge there tables.

In addition, if above not help, can you please share some sample data to test?

Regards,

Xiaoxin SHeng

[Anonymous]

I get this error even when using ADDCOLUMS to choose my colums from each table. Why does UNION think I don't have the same number of columns from each table? 

[amay15]

Thank you. This really helped:)