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OCP考试WORD文档(一小部分)
OCP考试WORD文档(一小部分)
OCP EXAM
Number: 1Z0-051
Passing Score: 800
Time Limit: 60 min
File Version: 9.02
Exam A
Exhibit
QUESTION 1
View the Exhibit and examine the structure of the SALES, CUSTOMERS, PRODUCTS, and TIMES tables.
The PROD_ID column is the foreign key in the SALES table, which references the PRODUCTS table. Similarly, the CUST_ID and TIME_ID columns are also foreign keys in the SALES table referencing the CUSTOMERS and TIMES tables, respectively.
Evaluate the following CREATE TABLE command:
CREATE TABLE new_sales(prod_id, cust_id, order_date DEFAULT SYSDATE)
AS
SELECT prod_id, cust_id, time_id FROM sales;
Which statement is true regarding the above command?
2018-01-22
Oracle_SQL_PL/SQL书写规范性能优化技巧.doc
PL/SQL书写规范
1、 语句中出现的所有表名、字段名全部小写,系统保留字、内置函数名、Sql保留字大写。
2、 连接符or、in、and、以及=、<=、>=等前后加上一个空格。
3、 对较为复杂的sql语句加上注释,说明算法、功能。
......
二、 书写优化性能建议
1、避免嵌套连接。例如:A = B and B = C and C = D
2、where条件中尽量减少使用常量比较,改用主机变量
2018-01-16
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