Please can someone help me with some light on using parameterized query?

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I am learning how to use parameterized query using ADO on SQL Server CE.
My question is, after appending parameters to the parameters collection, how does the comnand object tell the position of each parameter in the query.

Let's say I have the following query:

INSERT INTO Customers (CustomerName,CustomerAddr,CustomerCity) values(? , ?, ?)

How does it tell the orde of the paramers since no information is given about this when parameters were created and when they are appendes.Or does it deduce it from the order in which the parameters are. added?If yes, must that order be observed in writing the quety. I.e. in the example query. above , must the fields name be ordered in the order in which the parameters were appended?

Posted 20-Feb-14 22:53pm

Gbenbam

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Maarten Kools · Answer 1 · 2014-02-20T22:58:00

Solution 1

It tells the order by having to specify the parameter values in that order.

However, a more robust solution would be to use named parameters, e.g.

C#

SqlCeCommand cmd = new SqlCeCommand("INSERT INTO Customers (CustomerName,CustomerAddr,CustomerCity) values(@name , @addr, @city)");
cmd.Parameters.Add("@name", SqlDbType.NVarChar, 120).Value = "customer name";
cmd.Parameters.Add("@addr", SqlDbType.NVarChar, 120).Value = "customer address";
cmd.Parameters.Add("@city", SqlDbType.NVarChar, 120).Value = "customer city";

Posted 20-Feb-14 22:58pm

Maarten Kools

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Gbenbam 21-Feb-14 5:32am

Thanks.This is. so simple and straight forward.But this syntax. is C#'s isn't it?

Maarten Kools 21-Feb-14 5:43am

Yes, I assumed you used C# but I now notice you've tagged it C++. Here is an example[^] in C++.

Gbenbam 2-Mar-14 9:48am

Thanks your first solution is still very relevant.Whether C# or C++ , using named parameter is more rubust.By the way the C++ example you gave me link to doesnt use named parameters.That explains why your initial solution is still valid.