I have the following model:
public class LogData
{
public Guid ID { get; set; }
public string Name { get; set; }
}
I use Entity Framework Core to save those models to an SQLite database, it works well.
I need to delete from the data (it is dynamic, I can't use objects), so I use the following command:
string command="DELETE FROM LogData WHERE ID IN ('ea53b72a-4ab2-4f88-8f1d-0f96baa7cac7')";
context.Database.ExecuteSQLCommand(command);
According to the SQLite syntax , it is valid.
Unfortunately, as a result I get back 0, so no row was affected. When I remove the WHERE
condition, it deletes the contents of the table .
I have a guessing that as the key column is a Guid
and it is stored as a BLOB
, the plain SQLite engine can't find it.
So I tried to alter the command to this:
string command="DELETE FROM LogData WHERE HEX(ID) IN ('ea53b72a-4ab2-4f88-8f1d-0f96baa7cac7')";
context.Database.ExecuteSqlCommand(command);
Also tried this:
string command="DELETE FROM AuditLog WHERE HEX(ID) = 'ea53b72a-4ab2-4f88-8f1d-0f96baa7cac7'";
context.Database.ExecuteSqlCommand(command);
This, too:
string command="DELETE FROM AuditLog WHERE ID = 'ea53b72a-4ab2-4f88-8f1d-0f96baa7cac7'";
context.Database.ExecuteSqlCommand(command);
None of those helped.
What should I do about this?
The GUIDs are stored in the database as a binary BLOB
meaning you need to pass in a binary value to compare against. To do this you use the X'...'
notation. Additionally, you need to convert the endianness of the GUID to little endian. Fortunately, there's a handy extension method here to do your conversion:
public static Guid FlipEndian(this Guid guid)
{
var newBytes = new byte[16];
var oldBytes = guid.ToByteArray();
for (var i = 8; i < 16; i++)
newBytes[i] = oldBytes[i];
newBytes[3] = oldBytes[0];
newBytes[2] = oldBytes[1];
newBytes[1] = oldBytes[2];
newBytes[0] = oldBytes[3];
newBytes[5] = oldBytes[4];
newBytes[4] = oldBytes[5];
newBytes[6] = oldBytes[7];
newBytes[7] = oldBytes[6];
return new Guid(newBytes);
}
And you use it like this:
//The source GUID
var source = Guid.Parse("ea53b72a-4ab2-4f88-8f1d-0f96baa7cac7");
//Flip the endianness
var flippedGuid = source.FlipEndian();
//Create the SQL
var command = $"DELETE FROM AuditLog WHERE ID = X'{flippedGuid.ToString().Replace("-", "")}'";
context.Database.ExecuteSqlCommand(command);
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