Check sibling questions
Computer Science - Class 12
Chapter 8 - Database Concepts

Consider the following SQL command: CREATE TABLE MEMBER (MEM_ID INTEGER NOT NULL, NAME CHAR(15) NOT NULL, DATE_JOIN DATE, SEX CHAR(1) CHECK (SEX= ‘M’ OR SEX = ‘F’), ADDRESS VARCHAR(100) NOT NULL, PH_NO CHAR(15), PRIMARY KEY (MEM_NO), INDEX MEM_IDX (DATE_JOIN) );

Now answer the following questions:

NOT NULL ensures that

(A) Column cannot have blank value

(B) Column will not accept any value

(C) Column has a fixed value

(D) Column has a unique value

 

Answer:

By default, all columns in a table can hold null value ie., there is no particular value assigned for that column. The NOT NULL constraint ensures that a given column of a table is never assigned the null value.

So, the correct answer is (A)

 

Question 1 (ii)

By default format of date entered is

(A) DD-MM-YY

(B) MM-DD-YY

(C) YYYY-MM-DD

(D) DD-MM-YYYY

 

Answer:

The default format of date in SQL is YYYY-MM-DD.

Checking the options

  • (A) DD-MM-YY - It is not the default format of date in SQL.
  • (B) MM-DD-YY - It is not the default format of date in SQL.   
  • (C) YYYY-MM-DD - It is the default format of date in SQL.
  • (D) DD-MM-YYYY - It is not the default format of date in SQL.

So, the correct answer is (C)

 

Question 1 (iii)

The ______ constraint ensures that the value entered specifies a certain condition.

(A) NOT NULL

(B) NULL

(C) CHECK

(D) All of these

 

Answer:

Checking the options

  • (A) NOT NULL - Enforces a column to not accept null values.
  • (B) NULL - The NULL keyword is used to specify that a column can accept null values.
  • (C) CHECK - Limits the values that can be entered in certain columns based on a condition.
  • (D) All of these 

From the above explanation, it is clear that the CHECK constraint ensures that the value entered specifies a certain condition.

So, the correct answer is (C)

 

Question 1 (iv)

PRIMAY KEY in above example ensures that

(A) MEM_ID is entered primarily

(B) MEM_ID will hold a uniquely identified value

(C) MEM_ID will not remain blank

(D) All of these

 

Answer:

The primary key of a table uniquely identifies each record in the table. The value of the primary key should be unique and not null .

Checking the options

  • (A) MEM_ID is entered primarily - True for a primary key.   
  • (B) MEM_ID will hold a uniquely identified value - True for a primary key.  
  • (C) MEM_ID will not remain blank - True for a primary key.
  • (D) All of these 

Primary key ensures all the conditions given in the options.

So, the correct option is (D)

 

Question 1 (v)

The INDEX command in above example will

(A) Create an index on field DATE_JOIN

(B) Create an index namely MEM_IDX

(C) Both (a) and (b)

(D) None of the above

 

Answer:

The index command in MySQL creates indexes. They are used to retrieve data from the database more quickly than otherwise. The syntax to create an index is as follows:

CREATE INDEX index_name

ON table_name ( column1 , column2 , ...);  

The command INDEX MEM_IDX (DATE_JOIN) creates an index named MEM_IDX on the field DATE_JOIN.

Checking the options

  • (A) Create an index on field DATE_JOIN 
  • (B) Create an index namely MEM_IDX  
  • (C) Both (a) and (b)  
  • (D) None of the above 

Both option (A) and (B) are correct.

So, the answer is (C)


Transcript

Consider the following SQL command: CREATE TABLE MEMBER (MEM_ID INTEGER NOT NULL, NAME CHAR(15) NOT NULL, DATE_JOIN DATE, SEX CHAR(1) CHECK (SEX= ‘M’ OR SEX = ‘F’), ADDRESS VARCHAR(100) NOT NULL, PH_NO CHAR(15), PRIMARY KEY (MEM_NO), INDEX MEM_IDX (DATE_JOIN) ); Now answer the following questions: NOT NULL ensures that (A) Column cannot have blank value (B) Column will not accept any value (C) Column has a fixed value (D) Column has a unique value Answer: By default, all columns in a table can hold null value ie., there is no particular value assigned for that column. The NOT NULL constraint ensures that a given column of a table is never assigned the null value. So, the correct answer is (A) Question 1 (ii) By default format of date entered is (A) DD-MM-YY (B) MM-DD-YY (C) YYYY-MM-DD (D) DD-MM-YYYY Answer: The default format of date in SQL is YYYY-MM-DD. Checking the options (A) DD-MM-YY - It is not the default format of date in SQL. (B) MM-DD-YY - It is not the default format of date in SQL. (C) YYYY-MM-DD - It is the default format of date in SQL. (D) DD-MM-YYYY - It is not the default format of date in SQL. So, the correct answer is (C) Question 1 (iii) The ______ constraint ensures that the value entered specifies a certain condition. (A) NOT NULL (B) NULL (C) CHECK (D) All of these Answer: Checking the options (A) NOT NULL - Enforces a column to not accept null values. (B) NULL - The NULL keyword is used to specify that a column can accept null values. (C) CHECK - Limits the values that can be entered in certain columns based on a condition. (D) All of these From the above explanation, it is clear that the CHECK constraint ensures that the value entered specifies a certain condition. So, the correct answer is (C) Question 1 (iv) PRIMAY KEY in above example ensures that (A) MEM_ID is entered primarily (B) MEM_ID will hold a uniquely identified value (C) MEM_ID will not remain blank (D) All of these Answer: The primary key of a table uniquely identifies each record in the table. The value of the primary key should be unique and not null. Checking the options (A) MEM_ID is entered primarily - True for a primary key. (B) MEM_ID will hold a uniquely identified value - True for a primary key. (C) MEM_ID will not remain blank - True for a primary key. (D) All of these Primary key ensures all the conditions given in the options. So, the correct option is (D) Question 1 (v) The INDEX command in above example will (A) Create an index on field DATE_JOIN (B) Create an index namely MEM_IDX (C) Both (a) and (b) (D) None of the above Answer: The index command in MySQL creates indexes. They are used to retrieve data from the database more quickly than otherwise. The syntax to create an index is as follows: CREATE INDEX index_name ON table_name (column1, column2, ...); The command INDEX MEM_IDX (DATE_JOIN) creates an index named MEM_IDX on the field DATE_JOIN. Checking the options (A) Create an index on field DATE_JOIN (B) Create an index namely MEM_IDX (C) Both (a) and (b) (D) None of the above Both option (A) and (B) are correct. So, the answer is (C)

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