,store,store,store,store FROM bookinfo;//加减乘除取余 //余额大于200 //余额不等于200 SELECT * FROM readerinfo WHERE age IS NOT NULL//年龄不为空 //余额200到300 SELECT * FROM readerinfo WHERE NAME IN ('zhangfei','guanyu','liubei')//查询这几个读者的信息 SELECT * FROM readerinfo WHERE NA
Write a bash script to calculate the frequency of each word in a text file words.txt. For simplicity sake, you may assume: words.txt contains only lowercase characters and space ' ' characters. Each word must consist of lowercase characters only. Wor