for stand-alone service, the primary key ID is a long integer, which needs to be non-continuous. For example, self-increment cannot be implemented because it is continuous.
I thought of using System.nanoTime () to do ID, because I haven"t practiced it. I wonder if there will be ID repetition?
the question is: 1 is this possible?
2 No. NanoTime uses an uncertain start time and is likely to overlap after a restart.
you can use UUID.
Murphy's Law whenever it is possible to make a mistake, it is bound to go wrong, no matter how small the probability is.
cannot appear continuously, stand-alone service. For example, suppose you use self-increment ID to add System.nanoTime () to form a long type number ( is a string concatenation, not an addition ). This ID will not be repeated, because self-adding ID will not be repeated.
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problem description: a blog system is being developed that needs to achieve the top of an article, and then the foreground will display the article (or more than one) at the top. What I want is to add a new field to determine whether it is a top article...
try { connection.setAutoCommit(false); bankDao.transferMoney(+2000, 1, connection); 1 2000 if(true){ throw new RuntimeException(); } bankDao.transferMoney(-2000, 2, connection); 2 2000 ...