文件名称：操作符顺序-SQL语言基础
文件大小：5.26MB
文件格式：PPT
更新时间：2024-05-15 13:24:47
SQL 基础
操作符顺序 * SQL> SELECT ename, sal, 12*sal+100 2 FROM emp; ENAME SAL 12*SAL+100 ---------- --------- ---------- KING 5000 60100 BLAKE 2850 34300 CLARK 2450 29500 JONES 2975 35800 MARTIN 1250 15100 ALLEN 1600 19300 ... 14 rows selected. * Operator Precedence (continued) The example on the slide displays the name, salary, and annual compensation of employees. It calculates the annual compensation as 12 multiplied by the monthly salary, plus a one-time bonus of $100. Notice that multiplication is performed before addition. Note: Use parentheses to reinforce the standard order of precedence and to improve clarity. For example, the expression above can be written as (12*sal)+100 with no change in the result. Instructor Note Demo: l1prec1.sql, l1prec2.sql Purpose: To illustrate viewing a query containing no parentheses and executing a query with parentheses to override rules of precedence.