SQL Basics

Which SQL statement is used to retrieve data from database?

• INSERT

• DELETE

• SELECT

• UPDATE

What does the following Code snippet do?

ALTER TABLE STUDENT ADD(ADDRESS VARCHAR2(20));

• Adds a column called ADDRESS in table STUDENT

• Checks if column ADDRESS in the table STUDENT is VARCHAR

• Syntax Error

• None of the above

In "UPDATE Employees SET Age = Age + 1 WHERE Department IN ('Sales', 'HR') AND Age >= 30;",

identify the error.

• IN keyword is incorrect

• AND does not work in where with Update

• Expression in SET clause

• All Correct

When is the wildcard in WHERE clause used?

• An exact match is necessary for a CREATE statement.

• An exact match is not possible in a SELECT statement.

• An exact match is necessary for a SELECT statement.

• None of the above.

5. What is TRUE about UNION ALL Operator?

1. 
   

• 1. The results of both queries are combined with this operator.

  
  

• 1. After performing the UNION ALL operation, duplicate rows will not be removed.

  
  

• 1. Both A and B

• 1. None of the above

What is the difference between UNION & UNION ALL operators?

• 1. Combining the results of two select statements will be done using UNION whereas combined records from both queries are returned by UNION ALL operator.

  
  

• 1. Combining the results of two select statements will be done using UNION ALL whereas combined records from both queries are returned by UNION operator.

• 1. After performing the UNION operation, duplicate rows will not be removed whereas after performing the UNION ALL operation, duplicate rows will be removed.

• 1. None of the above

Which SQL constraint do we use to set some value to a field whose value has not been added explicitly?

• UNIQUE

• NOT NULL

• DEFAULT

• CHECK

What type of join returns all rows from both tables, joining records where matching & adding NULLs if there's no

match?

• CROSS JOIN

• INNER JOIN

• FULL OUTER JOIN

• LEFT JOIN