MySql - Update the values of a column for certain rows based on the values of another column
Well i have a situation, which i will explain with an example below

**Column 1    Column 2   Column 3**

       1       87       0
       6       89       0
       8       87       1
       9       87       0
      15       89       0
      18       90       1

so i have a case such that, the column3 value is unique for the same values of column2

so here lets consider column2 value as 87. So we have 3 such records, but i want a unique value for these three records in column3. So i mean there should be only one of these three records to have the value 1 in column3 and the rest should be having it as 0.

So lets say i want to update the value of column3 for these set of records to 1, where the column1 value is 9 and set the value of column3 to 0 when the column1 value is 8 and column2 value is 87. So i am unable to figure out how to do this. 

I tried by resetting all the column3 values to 0 if the column2 value is 87 and then update the particular required record. But that's not happening. Any other possible solution??
MySql - Update the values of a column for certain rows based on the values of another column
===

Well i have a situation, which i will explain with an example below

**Column 1    Column 2   Column 3**

       1       87       0
       6       89       0
       8       87       1
       9       87       0
      15       89       0
      18       90       1

so i have a case such that, the column3 value is unique for the same values of column2

so here lets consider column2 value as 87. So we have 3 such records, but i want a unique value for these three records in column3. So i mean there should be only one of these three records to have the value 1 in column3 and the rest should be having it as 0.

So lets say i want to update the value of column3 for these set of records to 1, where the column1 value is 9 and set the value of column3 to 0 when the column1 value is 8 and column2 value is 87. So i am unable to figure out how to do this. 

I tried by resetting all the column3 values to 0 if the column2 value is 87 and then update the particular required record. But that's not happening. Any other possible solution??