单项选择题
Which constraint can be defined only at the column level?（）
A. UNIQUE
B. NOT NULL
C. CHECK
D. PRIMARY KEY
E. FOREIGN KEY
相关考题
-
多项选择题
In which two cases would you use an outer join?（）
A. The tables being joined have NOT NULL columns.
B. The tables being joined have only matched data.
C. The columns being joined have NULL values.
D. The tables being joined have only unmatched data.
E. The tables being joined have both matched and unmatched data.
F. Only when the tables have a primary key/foreign key relationship. -
单项选择题
The PRODUCTS table has these columns: PRODUCT_ID NUMBER(4) PRODUCT_NAME VARCHAR2(45) PRICE NUMBER(8,2) Evaluate this SQL statement: SELECT * FROM PRODUCTS ORDER BY price, product _ name; What is true about the SQL statement?（）
A. The results are not sorted.
B. The results are sorted numerically.
C. The results are sorted alphabetically.
D. The results are sorted numerically and then alphabetically. -
单项选择题
Examine the structure of the EMPLOYEES, DEPARTMENTS, and TAX tables. For which situation would you use a nonequijoin query?（）
A. To find the tax percentage for each of the employees.
B. To list the name, job id, and manager name for all the employees.
C. To find the name, salary, and department name of employees who are not working with Smith.
D. To find the number of employees working for the Administrative department and earning less then 4000.
E. To display name, salary, manager ID, and department name of all the employees, even if the employees do not have a department ID assigned.
