UNPIVOT operation is a reverse process of PIVOT operation, but UNPIVOT is not the exact reverse of PIVOT. If PIVOT performs an aggregation and merges multiple rows into a single row in the output, then UNPIVOT can’t reproduce the original table-valued expression result because rows have been merged. So conclusion is that if PIVOT operation merges multiple row in a single row, then UNPIVOT operation can’t retrieve original table from the output of PIVOT operation. But if PIVOT operation doesn’t merge multiple row in a single row, then UNPIVOT operation can retrieve original table from the output of PIVOT operation.

For Example, the table Given below is stored in the database as pvt, and you want to rotate the column Emp1, Emp2, Emp3, Emp4, and Emp5 into row values that correspond to a particular vendor.

We need to identify two additional columns. The column that will contain the column values that we're rotating (Emp1, Emp2,....) will be called Employee, and the column that will hold the values that currently exist under the columns being rotated will be called Orders.

The output is as follows: