Entity framework core - select query (executesqlinterpolated)

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Hi

I am trying to get a column value using sql select query from the database in entity framework core. Don't know, what am i doing wrong here. I don't want to have tables converted to models in using Entity Framework Core in the solution.

This query is an one-off query.

Thanks & Regards,
Shweta

What I have tried:

var itemNo = "105744";

var myCommand = $"select MD.size from tbl_Stock_Master_data MD inner join tbl_StockGroupMaster on StkGrpID = ItemGroupID LEFT JOIN tbl_StockSizeOrdering O ON MD.SIZE = O.Size where itemno = '{itemNo}'";
                var size = motherLoadContext.Database.ExecuteSqlInterpolated(myCommand);

Posted 14-Jan-20 14:34pm

Member 14615490

Updated 15-Jan-20 13:12pm

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Wendelius 14-Jan-20 22:48pm

What is the problem, do you get an error message or some other issue?

3 solutions

Solution 1

Most likely the problem happens because ExecuteSqlInterpolated replaces the variables with parameters. In your case the parameter would be inside quotation marks and this probably causes the problem.

Have a try with something like

C#

var myCommand = $@"SELECT MD.size 
FROM tbl_Stock_Master_data MD 
INNER JOIN tbl_StockGroupMaster on StkGrpID = ItemGroupID 
LEFT JOIN tbl_StockSizeOrdering O ON MD.SIZE = O.Size 
WHERE itemno = {itemNo}";

var size = motherLoadContext.Database.ExecuteSqlInterpolated(myCommand);

Also the column in the where clause is missing the table alias so be sure to include that to prevent ambiguous names. Something like

WHERE md.itemno = {itemNo}"

Posted 14-Jan-20 16:58pm

Wendelius

Solution 2

ExecuteSqlInterpolated[^] expects the parameter to be a FormattableString[^].

Unfortunately, using var with an interpolated string creates a string variable instead. The parameter values will be injected directly into the resulting string, and you would leave yourself open to SQL Injection. Thankfully, you get a compiler error instead: cannot convert from 'string' to 'System.FormattableString'.

You'll also need to remove the single quotes from around the {itemNo} placeholder. EF will use a properly parameterized query, so this placeholder will be replaced with the parameter name. You don't need the quotes when you're using parameters.

You can either declare the variable type explicitly:

C#

FormattableString myCommand = $"select MD.size from tbl_Stock_Master_data MD inner join tbl_StockGroupMaster on StkGrpID = ItemGroupID LEFT JOIN tbl_StockSizeOrdering O ON MD.SIZE = O.Size where itemno = {itemNo}";

var size = motherLoadContext.Database.ExecuteSqlInterpolated(myCommand);

or inline the query variable:

C#

var size = motherLoadContext.Database.ExecuteSqlInterpolated($"select MD.size from tbl_Stock_Master_data MD inner join tbl_StockGroupMaster on StkGrpID = ItemGroupID LEFT JOIN tbl_StockSizeOrdering O ON MD.SIZE = O.Size where itemno = {itemNo}");

Posted 15-Jan-20 2:45am

Richard Deeming

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Member 14615490 · Accepted Answer · 2020-01-15T13:13:00

using (var command = motherLoadContext.Database.GetDbConnection().CreateCommand())
                {
                    command.CommandText = string.Format("select Colour from tbl_Stock_Master_data MD inner join tbl_StockGroupMaster on StkGrpID = ItemGroupID LEFT JOIN tbl_StockSizeOrdering O ON MD.SIZE = O.Size where itemno = '{0}'",itemNo);
                    motherLoadContext.Database.OpenConnection();
                    using (var result = command.ExecuteReader())
                    {
                        if (result.HasRows)
                        {
                            while (result.Read())
                            {
                                colour = result.GetString(0);
                            }
                        }
                    }
                }

This is the way we need to read a select statement.