Oracle SQL更新语句以什么顺序更改列值? [英] In which order Oracle SQL update statement changes column values?

问题描述

我得到了这句话

UPDATE TABLE_A SET COL_A = COL_B, COL_B = 0

我对它执行的顺序感到好奇，因为我希望COL_A应该包含我的COL_B的值，而COL_B应该是0，但是无论如何目前两个字段都为0.

I am curious about the sequence it execute because I expect COL_A should contain the value of my COL_B and COL_B should be 0 BUT somehow currently both fields are 0.

推荐答案

CREATE TABLE test2(A NUMBER, B NUMBER);

INSERT INTO TEST2 VALUES(1,2);

UPDATE TEST2 SET A=B,B=0;

执行后A = 2，B = 0

A=2,B=0 after execute

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