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Oracle's logical operator is also an essential factor in SQL statements. There are three

Logical operator

Meaning

And

Double-valued operator, if both the left and right conditions are true, the resulting value is true

Or

Double-valued operator, as long as one of the left and right conditions is true, the resulting value is true

Not

One-finger operator, if the original condition is true, then get true, if the meta-condition is false, on the contrary, if the original condition is false, then the result is true

The logical operator of Oracle is also used in SQL to make some examples:

Select * from emp where sal > 2000 and job = 'SALESMAN'

Look for employees whose salary is higher than 2000 and whose position is sales.

Select * from emp where job = 'CLERK' or deptno = 20

Look for a list of employees who work as CLERK or whose department is labeled 20

Select * from emp where not (sal > 3000 or sal

< 1500); 寻找那些工资既不大于3000也不小于1500，也即在1500到3000范围的员工，相当于：select * from emp where sal between 1500 and 3000; 结合到前面所列出的各类运算符，在这里汇总一下oracle中所有运算符的优先级句中必不可少的因素，一共有三个 运算符 级别 算术运算符(即'+','-'，'*','/') 1 连接运算符（即'||'） 2 比较运算符（即'>

',' > =','

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