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set serveroutput on declare a int:=100; b int:=200; c number; begin c:=(a+b)/(a-b); dbms_output.put_line(c); exception when zero_divide then dbms_outp 阅读全文
摘要:
select empno,ename,sal from scott.emp; SELECT empno,ename,sal FROM scott.emp; selECT empno,ename,sal frOM scott.emp; select empno,ename,sal from scott 阅读全文
摘要:
set pause on set pause '按<enter>键继续' select user_id,username,account_status from dba_users; show newpage set newpage 1 select user_id,username,account 阅读全文
摘要:
#绘制步调函数图像 import matplotlib.pyplot as plt x = [1,2,3,4] y = [0, 1, 2, 3] plt.step(x, y) plt.show() import numpy as np import pylab as plt from matplot 阅读全文