question archive Question 1 Suppose you want to find the position and satisfaction_level of all employees who left (i
Question 1 Suppose you want to find the position and satisfaction_level of all employees who left (i
Subject:BusinessPrice: Bought3
Question 1
Suppose you want to find the position and satisfaction_level of all employees who left (i.e., where the left field has value 1). Which of the following queries is the right query for this?
Select position, satisfaction_level
from t1
where left = 1;
Select position and satisfaction_level
from t1
where left = 1;
Select position, satisfaction_level
where left = 1;
Select position and satisfaction_level
where left = 1;
Question 2
Modify the query from Q1 so that you only see the position and satisfaction_level of those who left and also had satisfaction_level at least 0.80. How many such records are there in the dataset? Modify the query from Q1 so that you only see the position and satisfaction_level of those who left and also had satisfaction_level at least 0.80.
How many such records are there in the dataset?
549
577
3571
7218
Question 3
Write a SQL query to compute the average of the number of projects (field: "number_project") for employees who left the company. In which of the following ranges does it lie?
Less than or equal to 2.000.
Between 2.001 and 3.000.
Between 3.001 and 4.000.
Greater than or equal to 4.001.
Question 4
Suppose you want to list all records where the position is either "marketing" or "management". Which of the following queries will not work?
Select *
from t1
where position like "ma%";
Select *
from t1
where position = "marketing" or "management";
Select *
from t1
where position = "marketing" or position = "management";
Select *
from t1
where position like "%ma%";
Question 5
Write a SQL query that computes the satisfaction_level for each value of salary. If the salary values are ordered (low, medium, high), which of the following sequences of numbers lists the respective average satisfaction_level values?
0.601, 0.622, 0.637
0.637, 0.601, 0.622
0.622, 0.601, 0.637
0.637, 0.622, 0.601
Question 6
Which of the following statements is true?
Every data table must have at least one primary key, and the primary key column cannot have a null value.
Every data table must have at least one primary key, but the primary key column may have null values.
A data table need not have any primary key, but it must have at least one field of type integer.
A data table need not have any primary key, and the fields may be of any types.
Question 7
Which of the following is the most useful purpose of an API?
Identifying primary keys in a database.
Joining two or more tables in a database.
Converting primary data into secondary data.
Obtaining data from a different organization.
unanswered
Question 8
Consider the following query, using the movies datasets used in the video lectures:
select movie_title, year, count(distinct category)
from t1, t2
where t1.movie_title = t2.Nominee
group by movie_title, year;
Which of the following best describes the output of this query?
For each movie and year, it lists the number of Oscar nominations.
For each movie, it lists all the years in which it got Oscar nominations.
For each movie and year, it lists all movies that got Oscar nominations in at least two distinct categories.
For each movie and year, it lists all categories in which the movie got Oscar nominations, with the list sorted by movie name and year.
Question 9
Why may it be a bad idea to simply delete all rows which have one or more values or fields where the data is missing?
A.. It is not a bad idea to delete such rows.
B.. Deletion could cause our dataset to be biased.
C.. The fact that the data is missing may itself be useful information and point to inadequacies in our data collection process.
Both (b) and (c).
