04 Try it yourself Interactive

Break the register, then split it

The same six submissions and the same three operations, run twice. One table keeps the 1NF register from section 02 and performs the insert, the update and the delete on it. Two tables builds the 2NF decomposition row by row, checks the join gives the register back, then runs those same three operations again. Watch the bottom-right stat: it climbs three times in the first run and never leaves zero in the second. Nothing plays on its own, so use Next, Back and Reset, or the arrow keys.

One table
LAB_RECORD · 6 rows
Grey cells are key columns. Amber marks a copy of a fact already stored elsewhere in the table. Rose marks a row the database rejected, a row being removed, or a value that now disagrees with another. Emerald marks a correct outcome: a row newly written, a row an operation left untouched, or a join that reproduces the register.
Press Next to begin. Each press advances the run by one step.


      

        
Rows stored–

        
Repeated cells–

        
Students on record–

        
Anomalies hit0

      


      

      

        
        
        
        step 0 / 0