SELECT查询语句算数表达式
算数表达式:+加、-减、*乘、/除 (四则运算)
优先运算等级:遵循四则运算规则,先乘除后加减、同一优先级运算从左向右执行、括号内运算优先。
SQL@itkaifang> select * from emp; EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO ---------- ---------- --------- ---------- ---------- ---------- ---------- ---------- 7369 SMITH CLERK 7902 1980-12-17 800 20 7499 ALLEN SALESMAN 7698 1981-02-20 1600 300 30 7521 WARD SALESMAN 7698 1981-02-22 1250 500 30 7566 JONES MANAGER 7839 1981-04-02 2975 20 7654 MARTIN SALESMAN 7698 1981-09-28 1250 1400 30 7698 BLAKE MANAGER 7839 1981-05-01 2850 30 7782 CLARK MANAGER 7839 1981-06-09 2450 10 7788 SCOTT ANALYST 7566 1987-04-19 3000 20 7839 KING PRESIDENT 1981-11-17 5000 10 7844 TURNER SALESMAN 7698 1981-09-08 1500 0 30 7876 ADAMS CLERK 7788 1987-05-23 1100 20 7900 JAMES CLERK 7698 1981-12-03 950 30 7902 FORD ANALYST 7566 1981-12-03 3000 20 7934 MILLER CLERK 7782 1982-01-23 1300 10 14 rows selected. SQL@itkaifang> SELECT empno,ename,sal,sal*12+500 AS salary FROM emp; EMPNO ENAME SAL SALARY ---------- ---------- ---------- ---------- 7369 SMITH 800 10100 7499 ALLEN 1600 19700 7521 WARD 1250 15500 7566 JONES 2975 36200 7654 MARTIN 1250 15500 7698 BLAKE 2850 34700 7782 CLARK 2450 29900 7788 SCOTT 3000 36500 7839 KING 5000 60500 7844 TURNER 1500 18500 7876 ADAMS 1100 13700 7900 JAMES 950 11900 7902 FORD 3000 36500 7934 MILLER 1300 16100 14 rows selected. SQL@itkaifang> SELECT empno,sal,(sal+500)*12 AS salary FROM emp; EMPNO SAL SALARY ---------- ---------- ---------- 7369 800 15600 7499 1600 25200 7521 1250 21000 7566 2975 41700 7654 1250 21000 7698 2850 40200 7782 2450 35400 7788 3000 42000 7839 5000 66000 7844 1500 24000 7876 1100 19200 7900 950 17400 7902 3000 42000 7934 1300 21600 14 rows selected. SQL@itkaifang>