Part-2-(26-50)

What operator tests column for the absence of data?

answer choices

• IS BLANK operator

• IS ZERO operator

• IS NULL operator

• ISNULL operator

What does NULL mean?

answer choices

• The value NULL means UNKNOWN

• The value NULL means '' (empty string)

• The value NULL means ' ' (space character)

• The value NULL means ZERO

What is the value of the query:SELECT 'Nancy' + NULL + 'Smith'when evaluated on Microsoft SQL Server?

answer choices

• 'Nancy Smith'

• 'NancySmith'

• 'Nancy'

• NULL

Which SQL keyword is used to sort the result-set?

answer choices

• SORT BY

• SORT

• ORDER

• ORDER BY

Three properties of a lock in DBMS are:a)Granularity: the size of the lockb) Granularity: the type of the lockc) Mode: the type of the lockd) Duration: the time in seconds that the DBMS waits for a lock to be released

answer choices

• (a) and (c) and (d) are true

• (a) and (b) and (d) are true

• (b) and (c) and (d) are true

• (a) and (b) and (c) are true

A database transaction, by definition, must be ACID (atomic, consistent, isolated and durable). What does "Durable" mean?

answer choices

• "Durable" means that: Transactions provide an "all-or-nothing" proposition, stating that each work-unit performed in a database must either complete in its entirety or have no effect whatsoever

• "Durable" means that: Transactions must not violate any integrity constraints during its execution

• "Durable" means that: Transactions that have committed will survive permanently

• All of the others

What is the difference between the WHERE and HAVING SQL clauses?

answer choices

• The WHERE SQL clause condition(s) is applied to all rows in the result set before the HAVING clause is applied (if present). The HAVING clause is used only with SELECT SQL statements and specifies a search condition for an aggregate or a group

• None of the others

• The HAVING SQL clause condition(s) is applied to all rows in the result set before the WHERE clause is applied (if present). The WHERE clause is used only with SELECT SQL statements and specifies a search condition for an aggregate or a group

• The WHERE and the HAVING clauses are identical

Choose the correct statement.

answer choices

• You can remove a trigger by dropping it or by dropping the trigger table.

• The syntax to remove a trigger is: DROP TRIGGER <trigger_name>

• Use ALTER TRIGGER to change the definition of a trigger

• All of the others.

Suppose R and S are 2 relations. R is the parent of S.And the relationship between R and S is set to"ON DELETE CASCADE".This means that:

answer choices

• We can delete a row from R although that row has children in S (and in this case, all the children will be deleted too)

• We can delete a row from R if that row has children in S (and in this case, the database server will raise up an error)

To create a DEFAULT constraint on the "City" column of the table PERSON which is already created, use the following SQL:

answer choices

• ALTER TABLE PersonALTER COLUMN City SET DEFAULT 'SANDNES'

• ALTER TABLE PersonEDIT COLUMN City SET DEFAULT 'SANDNES'

• ALTER TABLE PersonUPDATE COLUMN City SET DEFAULT 'SANDNES'

• ALTER TABLE PersonMODIFY COLUMN City SET DEFAULT 'SANDNES'