Introduction

The table comparison strategy consist of the following steps:

Step 1 - Check column headers
The column headers of both old and new tables are checked for matches (commonalities). New column headers seen in the newer table are considered as 'columns added'. Column headers seen in the older table only are considered as 'columns removed'. In addition, the columns are checked if they have been shifted or been rearranged.

Step 2 - Check orientation identifier columns
Orientation columns can be supplied to declare specific columns as orientation or identifiers (such as names, serial numbers, etc.). See table compare(), 4th function parameter for details. Here, the algorithm checks that the orientation columns are existing in both tables to be compared.

Step 3 - Match rows with unique orientation identifier headers (Appicable if orientation headers are provided)
The function will match all rows in the new table with their corresponding rows in the old table which have the same contents under the orientation headers. In case multiple rows are identified (non-unique orientation identifier contents), then the best fitting corresponding line in the old table will be identified.

Step 4 - Match the remaining rows
In case no orientation headers are supplied, or non-unique rows with same orientation identifier values are still existing, then these rows will be matched by comparing the remaining columns (or all columns if no orientation identifier has been provided).
1st round: Zero tolerance is applied. All identical rows are matched. If matches exist, mate them and consider them as done.
2nd round: Check for rows where all entries except one are equal. If matches exist, mate them.
3rd round: Check for rows where all entries except two are equal. If matches exist, mate them.
4th round: Continue like above, opening up the comparison tolerance.
Finally: If all contents in a row are different, then the row in the old table is considered 'removed' and the new row considered 'added'.

Step 5 - Generate the report according to the chosen reporting option

Step 6 - Add statistical summary
The statistical summary will be added to the right hand side of the report. In this case, two additionals columns called Statistics Parameters and Statistics Values are introduced.

See also

Table Comparison Reports