Introduction
The
most awaited feature has arrived - "Table-Valued parameters in SQL Server
2008". Here, I would discuss on how to use this new feature with .net.
Problem
Statement
Before to the introduction of table-valued
parameters in SQL Server 2008, the options for passing data from multiple rows
of a DataTable to a stored procedure or a parameterized SQL command were
limited. Some of the possible options for a developer until now
were:
1. Make multiple parameters, with one parameter
representing one column of the DataTable
2. Create XML string & then parse it in the SP
3. Create a delimiter separated string & then
parse it in the SP
Also, the above stated options had to be repeated
for each row....hhuuuuuuuuhh.......just imagine the round trips to the server
for large DataTables or the complex logic to be implemented for parsing the
parameters.
Solution
with Table-Valued parameter
1. Creating
Table-Valued Parameter Types
CREATE TYPE dbo.TableType AS TABLE
( Col1 int, Col2 nvarchar(50),Coln ... )
2. Create Stored Procedure with a table valued parameter
CREATE PROCEDURE dbo.StoredProc
(@TableType
dbo.TableType READONLY)
NOTE
: The READONLY keyword is required for declaring a table-valued parameter.
3. Use the parameter as under -
For Insert
INSERT INTO dbo.Tbl (Col1,Col2)
SELECT paramTbl.Col1, paramTbl.Col2
FROM @TableType
AS paramTbl;
For Update
UPDATE dbo.Tbl
SET Tbl.Col2 = paramTbl.Col2
FROM dbo.Tbl
INNER JOIN @TableType AS
paramTbl
ON dbo.Tbl.Col1 = paramTbl.Col1;
For Delete
DELETE FROM dbo.Tbl
FROM dbo.Tbl
INNER JOIN @TableType AS
paramTbl
ON dbo.Tbl.Col1 = paramTbl.Col1;
4. Calling from .net Code
// Assumes connection is an open SqlConnection
object.
using (connection)
{
// Create a
DataTable with the modified rows.
DataTable addedValues =
ValuesDataTable.GetChanges(DataRowState.Added);
// Configure the SqlCommand and SqlParameter.
SqlCommand insertCommand =
new SqlCommand("SP_Name", connection);
insertCommand.CommandType = CommandType.StoredProcedure;
SqlParameter tvpParam =
insertCommand.Parameters.AddWithValue("@TableType
", addedValues );
tvpParam.SqlDbType = SqlDbType.Structured;
// Execute the command.
insertCommand.ExecuteNonQuery();
}
Limitations of
Table-Valued parameter
1. User-defined functions do not support Table
valued parameters.
2. Table-valued parameters can only be indexed to
support UNIQUE or PRIMARY KEY constraints.
3. SQL Server does not maintain statistics on
table-valued parameters.
4. Table-valued parameters are read-only in
Transact-SQL code. You cannot update the column values in the rows of a
table-valued parameter and you
cannot insert or delete rows. To modify the data
that is passed to a stored procedure or parameterized statement in table-valued
parameter, you must
insert the data into a temporary table or into a
table variable.
5. You cannot use ALTER TABLE statements to modify
the design of table-valued parameters.
6. If you are using Entity Framework 1.0, DBType
enum does not support Structured type.
As
a work around, create a SQLParameter & then typecast it into DbParameter.
SqlParameter param = new SqlParameter("@TableType", addedValues );
param.SqlDbType = SqlDbType.Structured;
command.Parameters.Add(param as DbParameter);
Reference
