To select all the records from a table named "Persons" where the value of the column "FirstName" starts with an "a", you can use the LIKE operator with the 'a%' pattern.
Let's go through each option to understand why it is correct or incorrect:
Option A) SELECT * FROM Persons WHERE FirstName='%a%' - This option is incorrect because the '%' wildcard should be placed at the end of the pattern to match any characters after 'a'.
Option B) SELECT * FROM Persons WHERE FirstName LIKE '%a' - This option is incorrect because the '%' wildcard should be placed at the beginning of the pattern to match any characters before 'a'.
Option C) SELECT * FROM Persons WHERE FirstName='a' - This option is incorrect because it only selects the records where the FirstName column has the exact value of 'a', not the ones that start with 'a'.
Option D) SELECT * FROM Persons WHERE FirstName LIKE 'a%' - This option is correct because it uses the '%' wildcard at the end of the pattern to match any characters after 'a', effectively selecting all the records where the FirstName column starts with 'a'.
Option E) SELECT * FROM Persons WHERE FirstName='a'" - This option is incorrect because it only selects the records where the FirstName column has the exact value of 'a', not the ones that start with 'a'.
The correct answer is Option D. This option is correct because it uses the LIKE operator with the 'a%' pattern to select all the records where the value of the column "FirstName" starts with an "a".