OCP

【推荐】2019 Java 开发者跳槽指南.pdf(吐血整理) >>> Choose two Examine this SQL statement: DELETE FROM employees e WHERE EXISTS (SELECT 'dummy' FROM emp_history WHERE employee_id = e.employee_id) Which two are true? A) The subquery is executed for every row in the EMPLOYEES table. B) The subquery is not a correlated subquery. C) The subquery is executed before the DELETE statement is executed. D) All existing rows in the EMPLOYEEE table are deleted. E) The DELETE statement executes successfully even if the subquery selects multiple rows. Answer：：AE (解析：这又是一个关联子查询的考题，出现过多次，A 答案大家要注意。) 关联子查询： 1、 先执行主查询

【推荐】2019 Java 开发者跳槽指南.pdf(吐血整理) >>> choose three The ORDERS table has a primary key constraint on the ORDER_ID column. The ORDER_ITEMS table has a foreign key constraint on the ORDER_ID column,referencing the primary key of the ORDERS table. The constraint is defined with on DELETE CASCADE. There are rows in the ORDERS table with an ORDER_TOTAL less than 1000. Which three DELETE statements execute successfully? A) DELETE FROM orders WHERE order_total<1000; B) DELETE * FROM orders WHERE order_total<1000; C) DELETE orders WHERE order_total<1000; D) DELETE FROM orders; E) DELETE order_id FROM

【推荐】2019 Java 开发者跳槽指南.pdf(吐血整理) >>> Choose two. Which two statements are true about single row functions? A) CONCAT : can be used to combine any number of values B) MOD : returns the quotient of a division operation C) CEIL : can be used for positive and negative numbers D) FLOOR : returns the smallest integer greater than or equal to a specified number E) TRUNC : can be used with NUMBER and DATE values Answer：：CE (解析：concat 函数只能连接两个字符串或者两个列的值。 ceil 函数向上取整数。 floor 函数向下取整。) SQL> select ceil(-500.1) from dual; CEIL(-500.1) ------------ -500 SQL> select ceil(-500.99999) from dual; CEIL(-500.99999

Choose two. Which two statements are true about single row functions? A) CONCAT : can be used to combine any number of values B) MOD : returns the quotient of a division operation C) CEIL : can be used for positive and negative numbers D) FLOOR : returns the smallest integer greater than or equal to a specified number E) TRUNC : can be used with NUMBER and DATE values Answer：：CE (解析：concat 函数只能连接两个字符串或者两个列的值。 ceil 函数向上取整数。 floor 函数向下取整。) SQL> select ceil(-500.1) from dual; CEIL(-500.1) -500 SQL> select ceil(-500.99999) from dual; CEIL(-500.99999) -500 SQL> select floor(-500.1) from dual; FLOOR

【推荐】2019 Java 开发者跳槽指南.pdf(吐血整理) >>> Choose two Exanine the desatption of the BOOKS_TRANSACTIONS table Name Null? Type ---------------------------------------------------------------------------------------------- TRANSACTION_ID NOT NULL VARCHAR2(6) TRANSACTION_TYPE VARCHAR2(3) BORROWED_DATE DATE BOOK_ID ARCHAR2(6) MEMBER_ID VARCHAR2(6) Examine this partial SQL statement: SELECT * FROM books_transctions; Which two WHERE condtions give the same resut? A) WHERE borrowed_date = SYSDATE AND (transaction_type= 'RM' OR member_id IN ('A101','A102' ) ); B) WHERE borrowed_date = SYSDATE AND transaction

choose two. You need to calculate the number of days from 1st January 2019 until today. Dates are stored in the default format of DD-MON-RR. Which two queries give the required output? A) SELECT SYSDATE - TO_DATE (' 01-JANUARY-2019' ) FROM DUAL; B) SELECT TO_DATE (SYSDATE, ' DD/MONTH/YYYY' ) - '01/JANUARY/2019' FROM DUAL; C) SELECT ROUND (SYSDATE - TO_DATE(' 01/JANUARY/2019' ) ) FROM DUAL; D) SELECT TO_CHAR (SYSDATE, ' DD-MON-YYYY') - '01-JAN-2019' FROM DUAL; E) SELECT ROUND (SYSDATE- '01-JAN-2019') FROM DUAL: Answer：AC (解析：在进行日期计算的时候需要用转换函数把字符型的转换成日期型，oracle 不会隐式转换。) 来源： 51CTO 作者： cto_5359 链接

Choose two Exanine the desatption of the BOOKS_TRANSACTIONS table Name Null? Type TRANSACTION_ID NOT NULL VARCHAR2(6) TRANSACTION_TYPE VARCHAR2(3) BORROWED_DATE DATE BOOK_ID ARCHAR2(6) MEMBER_ID VARCHAR2(6) Examine this partial SQL statement: SELECT * FROM books_transctions; Which two WHERE condtions give the same resut? A) WHERE borrowed_date = SYSDATE AND (transaction_type= 'RM' OR member_id IN ('A101','A102' ) ); B) WHERE borrowed_date = SYSDATE AND transaction_type= 'RM' OR member_id IN ('A101','A102' ) ; C) WHERE borrowed_date = SYSDATE AND (transaction_type= 'RM' AND member_id='A101' OR

Choose two Exanine the desatption of the BOOKS_TRANSACTIONS table Name Null? Type ---------------------------------------------------------------------------------------------- TRANSACTION_ID NOT NULL VARCHAR2(6) TRANSACTION_TYPE VARCHAR2(3) BORROWED_DATE DATE BOOK_ID ARCHAR2(6) MEMBER_ID VARCHAR2(6) Examine this partial SQL statement: SELECT * FROM books_transctions; Which two WHERE condtions give the same resut? A) WHERE borrowed_date = SYSDATE AND (transaction_type= 'RM' OR member_id IN ('A101','A102' ) ); B) WHERE borrowed_date = SYSDATE AND transaction_type= 'RM' OR member_id IN ('A101',

choose the best answer The CUSTOMERS table has a CUST_LAST_NAME column of data type VARCHAR2. The table has two rows whose COST_LAST_MANE values are Anderson and Ausson. Which query produces output for CUST_LAST_SAME containing Order for the first row and Aus for the second? A) SELECT REPLACE (REPLACE(cust_last_name,'son',''),'An','O') FROM customers; B) SELECT REPLACE (TRIM(TRALING 'son' FROM cust_last_name), 'An','O') FROM customers; C) SELECT INITCAP (REPLACE(TRIM('son' FROM cust_last_name),'An','O')) FROM customers; D) SELECT REPLACE (SUBSTR(cust_last_name,-3), 'An', 'O') FROM customers;

　　好程序员Java教程分享几个流行的Java框架 一.springmvc框架 简介：SpringWebMVC是一种基于Java的实现了WebMVC设计模式的请求驱动类型的轻量级Web框架，即使用了MVC架构模式的思想，将web层进行职责解耦，基于请求驱动指的就是使用请求-响应模型，框架的目的就是帮助我们简化开发，SpringWebMVC也是要简化我们日常Web开发的。 优点： 1.调理清晰，控制器(controller)、验证器(validator)、命令对象(commandobect)、表单对象(formobject)、模型对象(modelobject)、Servlet分发器(DispatcherServlet)、处理器映射(handlermapping)、试图解析器(viewresoler)等等，让你学习时能层次分明。 2、分工明确，而且扩展点相当灵活，可以很容易扩展，虽然几乎不需要； 3、由于命令对象就是一个POJO，无需继承框架特定API，可以使用命令对象直接作为业务对象； 4、和Spring其他框架无缝集成，是其它Web框架所不具备的； 5、可适配，通过HandlerAdapter可以支持任意的类作为处理器； 6、可定制性，HandlerMapping、ViewResolver等能够非常简单的定制； 7、功能强大的数据验证、格式化、绑定机制； 8