MCQ IN COMPUTER SCIENCE & ENGINEERING

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COMPUTER SCIENCE AND ENGINEERING

SQL

Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
With SQL, what wildcard symbol do you use to select all the columns from a table named “Persons”?
A
SELECT *.Persons
B
SELECT Persons
C
SELECT [all] FROM Persons
D
SELECT * FROM Persons
Explanation: 

Detailed explanation-1: -The LIKE operator is used in a WHERE clause to search for a specified pattern in a column. There are two wildcards often used in conjunction with the LIKE operator: The percent sign (%) represents zero, one, or multiple characters. The underscore sign ( ) represents one, single character.

Detailed explanation-2: -The ! wildcard in SQL is used to exclude characters from a string. For example, SELECT * FROM Customers WHERE last name LIKE ‘[!

Detailed explanation-3: -Retrieving All Columns When you specify a wildcard (*), all the columns in the table are returned.

Detailed explanation-4: -SELECT column1, column2 FROM table1, table2 WHERE column2=’value’; In the above SQL statement: The SELECT clause specifies one or more columns to be retrieved; to specify multiple columns, use a comma and a space between column names. To retrieve all columns, use the wild card * (an asterisk).

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