比如
，where col_a = 'a' and col_b = 'b' and col_c = 'c' or col_d = 'd' and col_e = 'e' or col_f = 'f'……
如果改变他们之间的顺序会怎样？
可以通过括号来设置判断的先后次序么？
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当然有变化

col_a = 'a' and col_b = 'b' and col_c = 'c' or col_d = 'd' and col_e = 'e' or col_f = 'f'……

（col_a = 'a' and col_b = 'b' and col_c = 'c'） or （col_d = 'd' and col_e = 'e'） or （col_f = 'f'……）

col_a = 'a' and col_b = 'b' or col_d = 'd' and col_c = 'c' and col_e = 'e' or col_f = 'f'…… ---d，c换了

（col_a = 'a' and col_b = 'b' ） or （col_d = 'd' and col_c = 'c' and col_e = 'e'） or （col_f = 'f'……）

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判断的顺序not and or 。
可以使用括号来执行先后的顺序。
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有OR的话最好用括号……