The print_r(), var_export(), and var_dump()functions are used with ____ to display the index and value of each element.
A. variables
B. functions
C. arrays
Answer: C
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In CLIQUE, the threshold used to find cluster density remains constant, even as the number of dimensions increases. This is a potential problem since density drops as dimensionality increases; i.e., to find clusters in higher dimensions the threshold has to be set at a level that may well result in the merging of low-dimensional clusters. Comment on whether you feel this is truly a problem and, if so, how you might modify CLIQUE to address this problem.
What will be an ideal response?
All Office application programs offer an installed reference tool that can assist you in using a program, known as ________
A) GUI B) Help C) Dynamic D) Windows
Query results are a recordset that provide an answer to a question posed in a query
Indicate whether the statement is true or false
For a simple BBS (Bulletin Board System) we use the following SQL statements to create two tables: one storing all posted messages and the other users who can post them.
CREATE TABLE Message ( mesgid INTEGER, poster INTEGER, subject CHAR(50), body CHAR(255), postdate DATETIME, PRIMARY KEY mesgid, FOREIGN KEY poster REFERENCES User (userid) ON DELETE CASCADE ON UPDATE CASCADE ) CREATE TABLE User ( userid CHAR(50), password CHAR(50), email CHAR(50), status CHAR(1), PRIMARY KEY(userid) )(a) There is an error in one of the above statements. Point out the error, explain why it is wrong and correct the error by rewriting that SQL statement. (b) Suppose there is a user with userid John in the database who has posted 100 messages. What will the DBMS do if we delete John from table User? What if we change John's userid to Michael? (c) Write an SQL statement to create a view of those messages with all their attributes that are posted by 'John'. (d) Write an SQL statement to create a domain such that the status attribute can only take two values, i.e., 'j' and 's'. (e) Suppose occasionally the system will post some announcement messages, but unfortunately, the system is not a user (thus it does not appear in the User table). How can you allow these messages being posted while not adding a ?system user? and not violating the foreign key constraint? (f) One desirable advanced feature of the BBS system is that each user can post messages not only to the public, but also to a subset of other users that are explicitly specied by userid when the message is posted. How would you change the denitions of the above two tables so that this new feature can be implemented? (You may introduce other tables if necessary.)