increment
.increment vs += 1
The source of increment is below, which initializes attribute to zero if nil and adds the value passed as by (default is 1), it does not do save, so .save is still necessary. def increment(attribute, by = 1) self[attribute] ||= 0 self[attribute] += by self end
How to increment value in PostgreSQL?
UPDATE totals SET total = total + 1 WHERE name=”bill”; If you want to make sure the current value is indeed 203 (and not accidently increase it again) you can also add another condition: UPDATE totals SET total = total + 1 WHERE name=”bill” AND total = 203;
i = i++ doesn’t increment i. Why? [duplicate]
The behavior is well defined in C# and the evaluation order is: Left side i is evaluated to the variable i Right side is evaluated to 0, and i is incremented (now i==1) The assignment is executed, it sets i to 0. (now i==0) The end result is i==0. In general you first create an …
Python dictionary increment
An alternative is: my_dict[key] = my_dict.get(key, 0) + num
post increment vs pre increment – Javascript Optimization
This is what I read and could answer your question: “preincrement (++i) adds one to the value of i, then returns i; in contrast, i++ returns i then adds one to it, which in theory results in the creation of a temporary variable storing the value of i before the increment operation was applied”.
Is incrementing a field in MySQL atomic?
The write is atomic but an increment also requires a read. So the question is: Are you sure the read is safe, in other words, are you sure another thread doing the increment will not end up with the same value to be incremented? I have doubts. The 100% correct way of doing this would …
SQL atomic increment and locking strategies – is this safe?
UPDATE query places an update lock on the pages or records it reads. When a decision is made whether to update the record, the lock is either lifted or promoted to the exclusive lock. This means that in this scenario: s1: read counter for image_id=15, get 0, store in temp1 s2: read counter for image_id=15, …