Primary Key Insert violation sometimes happening, but statement checks this - sql-server

Question

Maybe someone has an idea what I can check:
using (var cnn = new SqlConnection(connection))
{
cnn.Open();
using (var cmd = new SqlCommand())
{
cmd.Connection = cnn;
cmd.CommandText = "IF EXISTS (SELECT * FROM kruserprofile WHERE lactorid=#1 AND strname=#2) " +
" UPDATE kruserprofile SET txtvalue=#3 WHERE lactorid=#1 AND strname=#2 " +
"ELSE " +
" INSERT INTO kruserprofile (lactorid, strname, txtvalue) " +
" VALUES (#1, #2, #3)";
cmd.CommandTimeout = 120;
cmd.Parameters.AddWithValue("#1", actorId);
cmd.Parameters.AddWithValue("#2", ident);
cmd.Parameters.AddWithValue("#3", _mXml.ToString());
cmd.ExecuteNonQuery();
}
cnn.Close();
}
As you can see in this piece of code I do check if records exists and update or insert.
This works pretty fine on SQL Server systems.
On Azure SQL I do sometimes but not reproduce able the error:
Violation on PRIMARY KEY... where the constraint is on lactorid and strname.
Table:
CREATE TABLE dbo.kruserprofile (
lactorid int NOT NULL,
strname nvarchar(254) NOT NULL,
txtvalue nvarchar(max) NULL
);
GO
ALTER TABLE dbo.kruserprofile ADD CONSTRAINT PK__kruserpr__6E092EE804688C07 PRIMARY KEY (lactorid, strname);
GO
So I did not find any reason why, but sometimes it seems that the EXISTSreturns false so it try to insert which fails then. Any idea what I can check?

Answer 1

update:
Solution1:
We also have found the solution here.
Solution2:
I've created a test about using MERGE in Azure SQL.
Create table:
CREATE TABLE dbo.kruserprofile (
lactorid int NOT NULL,
strname nvarchar(254) NOT NULL,
txtvalue nvarchar(max) NULL
);
GO
ALTER TABLE dbo.kruserprofile ADD CONSTRAINT PK__kruserpr__6E092EE804688C07 PRIMARY KEY (lactorid, strname);
GO
Create a Table-valued parameter named dbo.kruserprofile_type, it will be used in my stored procedure:
create TYPE dbo.kruserprofile_type AS TABLE(
lactorid int NOT NULL,
strname nvarchar(254) NOT NULL,
txtvalue nvarchar(max)
)
GO
Create a Stored procedure, it will merge the same records and insert new records based on the primary key:
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
create PROCEDURE [dbo].[spUpsertKruserprofile]
#profile dbo.kruserprofile_type READONLY
AS
BEGIN
MERGE dbo.kruserprofile AS target_sqldb
USING #profile AS source_tblstg
ON (target_sqldb.lactorid = source_tblstg.lactorid and target_sqldb.strname = source_tblstg.strname )
WHEN MATCHED THEN
UPDATE SET
txtvalue = source_tblstg.txtvalue
WHEN NOT MATCHED THEN
INSERT (
lactorid,
strname,
txtvalue
)
VALUES (
source_tblstg.lactorid,
source_tblstg.strname,
source_tblstg.txtvalue
);
END
GO
After that, we can execute the stored procedure by following code:
DECLARE #profileVar AS dbo.kruserprofile_type;
/* Add data to the table variable. */
INSERT INTO #profileVar (lactorid, strname, txtvalue) values (1, 'tom','wednesday');
exec [dbo].[spUpsertKruserprofile] #profileVar
That's all.