Từ NULL khóa SQL được sử dụng để…

represent a missing or unknown value.

Which one of the following deletes all the entries but keeps the structure of the relation.

Delete from instructor where dept name= ’Finance’;

Delete from instructor where salary between 13000 and 15000;

Identify the correct syntax for IDENTITY property?

Column-name Data type IDENTITY(SEED, INCREMENT)

Column-name Data type IDENTITY (???)

Column-name IDENTITY(SEED, INCREMENT)

Column-name Data type IDENTITY(INCREMENT)

a column containing the primary key of another table

all of the above are above correct

The difference between the DELETE and TRUNCATE SQL clauses is:

The TRUNCATE clause deletes all rows in a database table, while the DELETE clause can have a WHERE condition and might or might not delete all rows in a table.

The DELETE clause deletes all rows in a database table, while the TRUNCATE clause can have a WHERE condition and might or might not delete all rows in a table.

The TRUNCATE clause is identical to the DELETE clause

The TRUNCATE clause deletes table structure and it's all data, while the DELETE clause can have a WHERE condition and might or might not delete all rows in a table.

LOCATIONS(subject_code, department_name, location_id, city); Which code snippet will alter the table LOCATIONS and change the datatype of the column CITY to varchar(30)?

ALTER TABLE locations MODIFY COLUMN (city varchar(30));

MODIFY TABLE locations ADD (city varchar(30));

ALTER TABLE locations ALTER COLUMN city varchar(30);

Which of the following is not true about complex views?

They contain no functions or grouping.

They derive data from more than one table.

You cannot perform DML operations through a complex view.

An index is a database table attribute, which speeds-up data search within a table.

An index is a special way to join 2 or more tables.

Which is the purpose of index in SQL?

It leads to enchance the query performance.

It lead to provide an index to a record.

It lead to perform fast searches.

Which one of the following is not true for a view?

They contain no functions or grouping.

They derive data from more than one table.

You cannot perform DML operations through a complex view.

In the UPDATE statement, if we do not use the WHERE clause, then:

All of the records will be updated

Will not execute the update statement

The SQL WHERE clause:

limits the row data are returned.

limits the column data that are returned.

Which of the following is true about the COUNT function?

COUNT(*) returns the number of rows in the table.

COUNT(exp) returns the number of rows with non-null values for the exp.

COUNT(DISTINCT exp) returns the number of unique, non-null values in the column.

Which of the following query is correct to select the highest salary of the employees in each Department?

SELECT e.dept_id, e.salary FROM Employee e GROUP BY e.dept_id ORDER BY MAX(e.salary);

SELECT e.dept_id, MAX(e.salary) FROM Employee e;

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

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.

The WHERE and the HAVING clauses are identical

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.

All of the above answers are not correct

What does the UNION operator do?

The UNION operator combines the results of two or more queries into one result that includes all the rows from the queries in the union.

The UNION operator sorts the selected result set.

The UNION operator behaves the same as the JOIN SQL clause.

What is purpose of CAST function in SQL Server?

It converts or cast an expression of 1 data type to another

Trong SQL, ABShàm được dùng để làm gì?

To return the absolute, positive value of a numeric expression.

To return the maximum value of a numeric expression.

To return the minimum value of a numeric expression.

The AVG SQL function returns the …

average in the values in agroup.

We refer to a join as a self-join when?

we are using left and right join together

we are joining more than 2 tables

How many tables can be included with a join?

D. All of the mentioned options

Which of the following statements is true concerning subqueries?

Involves the use of an inner and outer query

Cannot return the same result as a query that is not a subquery

Does not start with the word SELECT

Which of the following is a correlated subquery?

Uses the result of an outer query to determine the processing of an inner query

Uses the result of an inner query to determine the processing of an outer query

Uses the result of an inner query to determine the processing of an inner query

Uses the result of an outer query to determine the processing of an outer query

Sub-queries can be nested in?

UPDATE, DELETE, INSERT and SELECT statements.

Point out the WRONG statement.

OVER clause is not required in all ranking functions.

The ROW_NUMBER function simply assigns sequential numbering to the records of a result-set or to the records groups of a result-set.

SQL Server introduced four different ranking functions

Point out the WRONG statement.

NTILE() distributes the columns in an ordered partition into a specified number of groups.

RANK() returns the rank of each row in the result set of partitioned column.

DENSE_RANK() is same as RANK() function. Only difference is returns rank without gaps.

ROW_NUMBER() returns the serial number of the row order by specified column.

MySQL

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MULTIPLE CHOICE QUESTION

30 sec • 1 pt

Which of the following is described graphically using an E-R diagram?
Làm lại

Data flows between processes

Data source and destination

Entities and relationships between entities

Hierarchical data structure

MULTIPLE CHOICE QUESTION

30 sec • 1 pt

SQL query and modification commands make up a(n)

XML

DML

HTML

DDL

MULTIPLE CHOICE QUESTION

30 sec • 1 pt

A/an _________ is a piece of information that in some way describes an entity. It is a property of the entity and it quantifies, qualifies, classifies or specifies the entity.

Table

Process

ERD

Attribute

MULTIPLE CHOICE QUESTION

30 sec • 1 pt

What is the purpose of a Unique Constraint?

To uniquely determine a table and columns within that table.

To identify a specific row within a table, using one or more columns and/or foreign keys.

Create an entity that is unlike any other entity aside from itself.

To identify one unique instance of an entity, by using one or more attributes and/or relationships.

MULTIPLE CHOICE QUESTION

30 sec • 1 pt

Which of the following entities most likely contains invalid attributes?

Entity: Home. Attributes: Number of Bedrooms, Owner, Address, Date Built

Entity: Mother. Attributes: Name, Birthdate, Occupation, Salary

Entity: Car. Attributes: Owner Occupation, Owner Salary, Speed

Entity: Pet. Attributes: Name, Birthdate, Owner

MULTIPLE CHOICE QUESTION

30 sec • 1 pt

In a 1:N relationship, the foreign key is placed in:

either table without specifying parent and child tables

the parent table

the child table

either the parent table or the child table

MULTIPLE CHOICE QUESTION

30 sec • 1 pt

You are building a new database for a company with 10 departments. Each department contains multiple employees. In addition, each employee might work for several departments. How should you logically model the relationship between the department entity?

Create a mandatory one-to-many relationship between department and employee.

Create an optional one-to-many relationship between department and employee.

Create a new entry, create a one-to-many relationship from the employee to the new entry, and create a one-to-many relationship from the department entry to the new entry.

Create a new entry, create a one-to-many relationship from the new entry to the employee entry, and then create a one-to-many relationship from the entry to the department entry.

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MySQL

Which of the following is described graphically using an E-R diagram?
Làm lại

SQL query and modification commands make up a(n)

A/an _________ is a piece of information that in some way describes an entity. It is a property of the entity and it quantifies, qualifies, classifies or specifies the entity.

What is the purpose of a Unique Constraint?

Which of the following entities most likely contains invalid attributes?

In a 1:N relationship, the foreign key is placed in:

You are building a new database for a company with 10 departments. Each department contains multiple employees. In addition, each employee might work for several departments. How should you logically model the relationship between the department entity?

In a 1:1 relationship, the foreign key is placed in:

In which of the following can many entity instances of one type be related to many entity instances of another type?

What data type is “Distance from home to school ”should be?

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Similar Resources on Wayground

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MySQL

Which of the following is described graphically using an E-R diagram?Làm lại

SQL query and modification commands make up a(n)

A/an _________ is a piece of information that in some way describes an entity. It is a property of the entity and it quantifies, qualifies, classifies or specifies the entity.

What is the purpose of a Unique Constraint?

Which of the following entities most likely contains invalid attributes?

In a 1:N relationship, the foreign key is placed in:

You are building a new database for a company with 10 departments. Each department contains multiple employees. In addition, each employee might work for several departments. How should you logically model the relationship between the department entity?

In a 1:1 relationship, the foreign key is placed in:

In which of the following can many entity instances of one type be related to many entity instances of another type?

What data type is “Distance from home to school ”should be?

Access all questions and much more by creating a free account

Similar Resources on Wayground

Popular Resources on Wayground

Discover more resources for Other

Which of the following is described graphically using an E-R diagram?
Làm lại