Which SQL statement will accomplish the task?

View the Exhibit and examine the description for the CUSTOMERS table.
You want to update the CUST_CREDIT_LIMIT column to NULL for all the customers, where
CUST_INCOME_LEVEL has NULL in the CUSTOMERS table. Which SQL statement will accomplish the task?

View the Exhibit and examine the description for the CUSTOMERS table.

You want to update the CUST_CREDIT_LIMIT column to NULL for all the customers, where  CUST_INCOME_LEVEL has NULL in the CUSTOMERS table.

Which SQL statement will accomplish the task?

A.
UPDATE customers
SET cust_credit_limit = NULL
WHERE CUST_INCOME_LEVEL = NULL;

B.
UPDATE customers
SET cust_credit_limit = NULL
WHERE cust_income_level IS NULL;

C.
UPDATE customers
SET cust_credit_limit = TO_NUMBER(NULL)
WHERE cust_income_level = TO_NUMBER(NULL);

D.
UPDATE customers
SET cust_credit_limit = TO_NUMBER(‘ ‘,9999)
WHERE cust_income_level IS NULL;



Leave a Reply 8

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user

user

Is

= NULL (equal NULL)

the same as

IS NULL?

Fj

Fj

besides that one “makes sense” and the other will never return any rows?

nothing is equal to null
nothing is NOT equal to null

but a NULL can be “null”. When you need to retrieve NULLS, you must use “is null”

ops$tkyte@ORA9IR2> select * from dual where null=null;

no rows selected

ops$tkyte@ORA9IR2> select * from dual where null null;

no rows selected

ops$tkyte@ORA9IR2> select * from dual where null IS null;

D

X
(ask.Tom)

spellublind

spellublind

Why is D wrong?

sengottuvel

sengottuvel

there is space in to_number(‘ ‘,9999) thats why it is wrong

Jenny

Jenny

Because this space is considered a character, and the question is to update to NULL. Sorry if my english is not good.

Jenny

Jenny

Because this space is considered a character, and the question is to update to NULL. Sorry if my english is not good.

Hossam

Hossam

B.
UPDATE customers
SET cust_credit_limit = NULL
WHERE cust_income_level IS NULL;