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How to query data when columns are encrypted in SQL Server 2016

I've been trying to find solution in this problem. I encrypted my columns from my database in SQL Server 2016 . In order to read the data I already set the parameters "Column Encryption Setting=Enabled"; I know I don't have problem in my certificate because I was able to query like SELECT * FROM TABLE, but I wasn't able to query using a WHERE condition. For example
"SELECT column FROM Table WHERE column='abc'" something like that.
The Error is:
"Operand type clash: varchar is incompatible with varchar(8000)
encrypted with (encryption_type = 'DETERMINISTIC',... and so on"
I don't know why I can't retrieve the data from the encrypted column.

I assume you have encrypted your column using the Always Encrypted feature of SQL Server.
With Always Encrypted SQL Server does not know the keys for encrypting and decrypting your data. It's the job of your client application to encrypt data before sending it to SQL Server.
When you execute this query:
SELECT column FROM Table WHERE column='abc'
you are asking SQL Server to compare the non-encrypted varchar 'abc' to the encrypted values found in your encrypted column. This will fail - as you've noted yourself.
Your client application must encrypt the value you want to use in your WHERE clause before sending it off to SQL Server.
If you're using SSMS you can do this by enabling parameterization for always encrypted. You can enable this in SSMS under Query>>Query options>>Execution>>Advanced>>Enable Parameterization for Always Encrypted.
Once this is enabled you'll be able to filter your table like this:
DECLARE #MyValue VARCHAR(100) = 'abc';
SELECT [Column] FROM [Table] WHERE [Column] = #MyValue;
What happens behind the scenes is that SSMS encrypts the value of the #MyValue parameter for you before sending it off to SQL Server. It is important that you declare and initialize the parameter at once. Otherwise SSMS is unable to encrypt the value before sending the query to SQL Server.
You can read more about parameterization for always encrypted here. Feel free to comment below if the above explanation is unclear to you.

You need to use DECRYPTBYKEY
SELECT *
FROM Table WHERE convert(varchar,DecryptByKey(column))='abc'
The way you use this function depends on if you are using symmetric keys and a hash, or just a key, etc.

Update/Insert rows in SQL table with encrypted columns using LinqToSQL - Always Encrypt

I am trying to get a hands-on on Always Encrypt feature of SQL Server 2016. I am using an existing application and database to do this.
I have a table [User], where i have encrypted the 'Password' column with 'Deterministic' type. I have made the connection string changes and I am able to retrieve all the rows. I have created the repository for this table.
I am trying to insert and update rows in this table with LinqToSQL using InsertOnSubmit() and SubmitChanges().
But whenever I try to insert new rows or update existing rows, I get the error:
Msg 206, Level 16, State 2, Line 7 Operand type clash: varchar is
incompatible with varchar(20) encrypted with (encryption_type =
'DETERMINISTIC', encryption_algorithm_name =
'AEAD_AES_256_CBC_HMAC_SHA_256', column_encryption_key_name =
'CEK_Auto1', column_encryption_key_database_name = 'BRO_UAT')
collation_name = 'Latin1_General_BIN2'
I have read articles where using Stored Procs and parameterization has solved the issue. But, as I mentioned earlier, this is an existing project, and I have used LinqToSql and do not want to change the code. Insertion/Update works fine if the column is not encrypted!
Am I missing some setting?Please point me towards the right direction.

Change your column to nvarchar and check.
Also now even storing the password is not the best approach, store a signature instead and validate that signature when validating the password.
Check the link for the same.
https://social.msdn.microsoft.com/Forums/en-US/77bb69f0-590e-40f5-b5e9-714bf590e008/how-to-handle-encrypted-column?forum=linqtosql

Best practice for saving data in SQL

I am creating a survey. It is long enough that I want to give people a chance to save what they have so far. I am wondering what the best practice is for saving the data. Do I turn off foreign key constraints so if they haven't selected everything yet then foreign key constraint errors are ignored. In this example I use an ID to link the documents table to the table that holds what they have selected. If they haven't selected a document yet then a -1 is inserted as a holder. Or do I create a second table to hold the saved place data. Or is there a third option.

There is a 3rd option. You can generate the primary key right when the user begins the survey. There are two ways to do this:
Generate a database record and read-back the primary key (assumes
it's generated by the database)
Change the primary key to be a GUID
and simply generate a GUID in code.

OK, using -1 this way means that you have to have document in the documents table with an id of -1. If you don't a better structure would be to define the field as allowing nulls. Then you pass in a null value.
You might want to read this:
Can a foreign key be NULL and/or duplicate?

C# DataTable and PK

I'm having such a problem: got dataset with a table(s). Say, we have already several records in a table which has a primary key (autoincrement). Basically, program works fine until I insert a new row. Even I use method AcceptChanges or Update, the new row is commited but it existing datatable object lacks the newest primary key value which I need for furhter processing. Is the only method to reload all the table from database again or there is a better way for it?
Thanks,
Ray

You should add ';select SCOPE_IDENTITY()' to the end of your insert sql statement attached to your data adapter. That will read back the last inserted value generated by autoincrement and update your dataset.
I.e, your insert sql should resemble this:
insert into sometable(column1,column2) values(#column1,#column2); select * from sometable where primarykeycolumn=scope_identity()
Your existing dataset will then contain the primary keys when dataadaper.Update(dataset) returns.

If you have a connection object you could use
int = (int)conn.executeScalar("SELECT ##IDENTITY")
Modified by what datatype your primary key is.
This has to be done directly before any other operations as a new insert will replace the stored value in ##IDENTIY

Inserting data into C# Datasets

I am using C#.Net application in which i created a dataset.Now i want to create a method in which i will enter a record in one table which will return a value ie primary key.Now by using that primary key i have to insert records in 5 tables and i have to use that primary key as a foreign key for this 5 tables using dataset.

You need to tell your parent table's table-adapter to refresh the
data-table after update operation.
This is how you can do that.
Open the properties of ParentTableAdapter -> Default Select Query -> Advnaced options. and Check the option of Refresh the data table. Save the adapter now. Now when you call update on table-adapter, the data-table will be updated [refreshed] after the update operation and will reflect the latest values from database table. if the primary-key or any coloumn is set to auto-increment, the data-table will have those latest value post recent update.
Now you can Call the update as ParentTableAdapterObj.Update(ds.dataTable);
Read latest values from the ParentDataTable(ds.dataTable) coloumns and assign respective values into the child table before update. This will work exactly the way you want.
alt text http://ruchitsurati.net/files/tds1.png

Have you tried temporary key linkage until the DB generates the final key? Works great for me.