Hello
I have to create an Unique index only when in composite index there is a column(a4) assumes a value determined (S in my sample) otherwise with any other value, the row can be inserted
| create unique index abc_indx1 on abc_table((a1,a2,a3, |
| | if a4 = 's' error duplicate key |
| | otherwise(other values it's ok |
Is there someone who can help me
Thanks in advance