What does Column names in each table must be unique. mean?
SQL requires that all columns within a table contain a unique name. This error usually occurs when a user inadvertantly tries to create a table with duplicate column names. For example, views ‘Photoobj’ and ‘Galaxy’ both contain an ‘objid’ column, so if one tried a select * from both of these into a single table this error would occur. The fix is to explicity name the conflicting column as something else, so instead of doing ‘select ra from photoobj’ you could do ‘select ra as ra2 from photoobj’.
