FMResultSet, if the column is empty

transfer

[rs objectForColumnName:@"xxx"];

If column xxx has no value, the above code returns NSNull, but directly judges

if(NSNull){  
}

will be evaluated as true, thus executing the code in the curly braces. So the following code is wrong:

if([rs objectForColumnName:@"xxx"]){  
    // logic when column xxx has a value  
}

Even if column xxx has no value, it will go to the curly braces. The correct spelling should be:

NSNumber *defInt1 = [rs objectForColumnName:@"def_int1"];  
      
if(![defInt1 isEqual:[NSNull null]]){  
    // logic when def_int1 has a value  
}