Have you been wondering whether UNPIVOT is the best way for converting columns into rows? If so, then you’re not alone. So many people do not seem to understand the best route to take when looking forward to converting columns into rows. Before going any further, you need to understand the difference that exists between PIVOT and UNPIVOT operators in SQL server.
To cut the long story short, the PIVOT and UNPIVOT relational operators are relied upon when changing a table-valued expression into another table. It basically involves data rotation. PIVOT SQL is mostly applicable when there’s need to convert table rows into columns.
If this is not enough, it allows users to perform aggregations whenever necessary especially for column values expected in the final output. Things tend to be different when you want to convert data from column-level back to row-level and get the original table. When this is the case, it would be better for you to use the UNPIVOT SQL operator.
You should, however, keep in mind that UNPIVOT is not a complete opposite of PIVOT function. In fact, it is only possible if the pivoted table does not have aggregated data. Furthermore, UNPIVOT function does not reproduce the initial table-valued expression result. This is possible since the rows have already been merged.
PIVOT aggregates data on the other hand are capable of merging a bunch of rows into a single row. In case the input of UNPIVOT SQWL disappears in the output, then it might be a clear sign that there might be null values in the input just before the PIVOT operation.
The Bottom Line
There you have it, some of the things you need to know before you can finally rely on the UNPIVOT function to convert columns into rows. If you’re still finding it hard, simply seek the help of your friends or colleagues who have a clear understanding of the UNPIVOT SQL function. Alternatively, you can contact experts in the field and you’re good to go. It is then that you will have an easy time when converting columns into rows.