how to encrypt a column with a key (SQL 2012)

I have created a Certificate and a symmetric key, in this user database. How exactly should encryption of the column happen so that no one can just do a SELECT to read the data without knowing the symmetric key (making the data secure)?

in the below example,
FirstColumn  should not be readable by anyone.

   create table test (FirstColumn int)
 insert into test select 1111
 select * from test --displays int
 alter table test alter column FirstColumn varbinary(10)  
 select * from test --displays binary
 SELECT CAST(FirstColumn as int),FirstColumn from test
 alter table test alter column FirstColumn int
 select * from test --displays int
 drop table test
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Neil RussellTechnical Development LeadCommented:
You have missed the point of how this works.
There is a complete example on mssqltips Dot Com that has clear step by step instructions on how to do this.
In short the steps involved are far more complex than you seem to think.  The data is stored in an encrypted format and doing a simple select will only return the encrypted data and that will mean nothing to anybody.

You need to add a new field to hold your encrypted data, created using EncryptByKey() passing in your symetric key and your plain data.

Then you can delete the column with your plain data in it and the encrypted data can only be read using, in unencrypted form, using DecryptByKey() passing in your encrypted field data.

Have a look at the full article and you will be flying. Simple and easy to follow.

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Microsoft SQL Server 2008

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