46、(10-4) choose two:
Examine the data in the CUST_NAME column of the CUSTOMERS table.
CUST_NAME
----------------------
Lex De Haan
Renske Ladwig
Jose Manuel Urman
Jason Mallin
You want to extract only those customer names that have three names and display the * symbol in
place of the first name as follows:
CUST_NAME
-----------------------
*** De Haan
**** Manuel Urman
Which two queries give the required output?
A) SELECT LPAD(SUBSTR(cust_name,INSTR(cust_name,' ')),LENGTH(cust_name),'*') "CUST NAME" FROM customers
WHERE INSTR(cust_name, ' ',1,2)<>0;
B) SELECT LPAD(SUBSTR(cust_name,INSTR(cust_name,' ')),LENGTH(cust_name)- INSTR(cust_name,' '),'*') "CUST NAME"
FROM customers
WHERE INSTR(cust_name, ' ',1,2)<>0 ;
C) SELECT LPAD(SUBSTR(cust_name,INSTR(cust_name,' ')),LENGTH(cust_name),'*') "CUST NAME"
FROM customers
WHERE INSTR(cust_name, ' ',-1,2)<>0;
D) SELECT LPAD(SUBSTR(cust_name,INSTR(cust_name,' ')),LENGTH(cust_name)- INSTR(cust_name,' '),'*') "CUST NAME"
FROM customers
WHERE INSTR(cust_name, ' ',-1,-2)<>0;
Answer：AC
(解析：题意是：您希望只提取具有三个名称的那些客户名称，并显示*符号来代替名称如下注意条件的用法 INSTR(cust_name, ' ',1,2)<>00，意思是从名字中找空格，从第一个开始，查看第二个空格的位置，如果有，说明名字里面就有三个名称，否则只有两个名称。同时INSTR(cust_name, ' ',-1,-2)，从倒数第一个空格开始，不能再用-2 了，要用正数)