Is this code PHP MySQL redundant?

The sentence of red box , Is it redundant ？

Only for lock id = 1 For this record .

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Other answers 1：

It should be redundant , Because the transaction itself will trigger table lock or row lock .
However, for the logic in the diagram, it is usually better to consider a more accurate way , For example, the original data is id=1,num=1, So direct execution update table set num=2 where id = 1 and num = 1, In this way, double writing can be avoided without locking .