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Concept explainers
Aggregate Functions:
SQL has some built-in functions and they are called as aggregate functions. SQL contains five built-in functions. They are:
- SUM – This function is used to add values from the particular column.
- Syntax: SELECT SUM(column_Name) FROM table_Name;
- COUNT – This is used to count the number of rows for the particular column.
- Syntax: SELECT COUNT(column_Name) FROM table_Name;
- MAX – This function is used to get the maximum value from the column.
- Syntax: SELECT MAX(column_Name) FROM table_Name;
- MIN – This function is used to get the minimum value from the column.
- Syntax: SELECT MIN(column_Name) FROM table_Name;
- AVG – This function is used to get the average of all the values from the column.
- Syntax: SELECT AVG(column_Name) FROM table_Name;
Grouping Rows:
SQL contains “GROUP BY” clause in order to group rows by common data. Though it is very powerful feature, it is hard to understand.
Syntax:
SELECT column_Name1 FROM table_Name GROUP BY column_Name2;
Example: Consider a table “student” contains two columns “student_Name” and “Department”. “GROUP BY” clause is used when there is a need to get the number of students from each department. The query for this scenario is given as follows.
SELECT department, COUNT (department) FROM student GROUP BY department;
When the above query is executed, number of students from each department will be displayed.
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Chapter 7 Solutions
Database Systems: Design, Implementation, & Management
- solve this questions for me .arrow_forwarda) first player is the minimizing player. What move should be chosen?b) What nodes would not need to be examined using the alpha-beta pruning procedure?arrow_forwardConsider the problem of finding a path in the grid shown below from the position S to theposition G. The agent can move on the grid horizontally and vertically, one square at atime (each step has a cost of one). No step may be made into a forbidden crossed area. Inthe case of ties, break it using up, left, right, and down.(a) Draw the search tree in a greedy search. Manhattan distance should be used as theheuristic function. That is, h(n) for any node n is the Manhattan distance from nto G. The Manhattan distance between two points is the distance in the x-directionplus the distance in the y-direction. It corresponds to the distance traveled along citystreets arranged in a grid. For example, the Manhattan distance between G and S is4. What is the path that is found by the greedy search?(b) Draw the search tree in an A∗search. Manhattan distance should be used as thearrow_forward
- whats for dinner? pleasearrow_forwardConsider the follow program that prints a page number on the left or right side of a page. Define and use a new function, isEven, that returns a Boolean to make the condition in the if statement easier to understand. ef main() : page = int(input("Enter page number: ")) if page % 2 == 0 : print(page) else : print("%60d" % page) main()arrow_forwardWhat is the correct python code for the function def countWords(string) that will return a count of all the words in the string string of workds that are separated by spaces.arrow_forward
- Consider the following program that counts the number of spaces in a user-supplied string. Modify the program to define and use a function, countSpaces, instead. def main() : userInput = input("Enter a string: ") spaces = 0 for char in userInput : if char == " " : spaces = spaces + 1 print(spaces) main()arrow_forwardWhat is the python code for the function def readFloat(prompt) that displays the prompt string, followed by a space, reads a floating-point number in, and returns it. Here is a typical usage: salary = readFloat("Please enter your salary:") percentageRaise = readFloat("What percentage raise would you like?")arrow_forwardassume python does not define count method that can be applied to a string to determine the number of occurances of a character within a string. Implement the function numChars that takes a string and a character as arguments and determined and returns how many occurances of the given character occur withing the given stringarrow_forward
- Consider the ER diagram of online sales system above. Based on the diagram answer the questions below, a) Based on the ER Diagram, determine the Foreign Key in the Product Table. Just mention the name of the attribute that could be the Foreign Key. b) Mention the relationship between the Order and Customer Entities. You can use the following: 1:1, 1:M, M:1, 0:1, 1:0, M:0, 0:M c) Is there a direct relationship that exists between Store and Customer entities? Answer Yes/No? d) Which of the 4 Entities mention in the diagram can have a recursive relationship? e) If a new entity Order_Details is introduced, will it be a strong entity or weak entity? If it is a weak entity, then mention its type?arrow_forwardNo aiarrow_forwardGiven the dependency diagram of attributes {C1,C2,C3,C4,C5) in a table shown in the following figure, (the primary key attributes are underlined)arrow_forward
- Database Systems: Design, Implementation, & Manag...Computer ScienceISBN:9781305627482Author:Carlos Coronel, Steven MorrisPublisher:Cengage LearningA Guide to SQLComputer ScienceISBN:9781111527273Author:Philip J. PrattPublisher:Course Technology Ptr
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