A database can show whether certain mathematical mistakes occur repeatedly.
For example, you may discover that you frequently call too wide against turn bets, defend certain draws too aggressively, or fail to continue with hands that have sufficient equity.
Analyzing your hands with database analysis can help identify patterns across hundreds or thousands of hands instead of relying on isolated examples.
A useful hand base analysis should therefore connect statistics with individual hands. Statistics can show that a particular situation may be problematic, while hand review can explain why the problem occurs.
This combination is much more informative than looking at a single percentage without understanding the decisions behind it.