Why is Parameter Order Crucial in OleDbCommand Objects When Using CommandType Text?

The Importance of Parameter Order in OleDbCommand Objects

When creating OleDbCommand objects, the order in which OleDbParameter objects are added to the OleDbParameterCollection is crucial for the proper execution of queries. This is because OleDbCommand does not support named parameters for passing parameters to SQL statements or stored procedures when CommandType is set to Text.

Example:

Consider the following query:

SELECT * FROM tblSomeThing WHERE id = @id AND debut = @dtDebut AND fin = @dtFin

If you add the parameters in the following order:

cmd.Parameters.Add("@id", OleDbType.Integer).Value = idSociete;
cmd.Parameters.Add("@dtFin", OleDbType.Date).Value = dateTraitementFin;
cmd.Parameters.Add("@dtDebut", OleDbType.Date).Value = dateTraitementDebut;

you will get no results. This is because the order of the parameters added does not match the order in which they appear in the query.

Solution:

To ensure the correct execution of the query, you must respect the order of parameters in the query string. In this case, the correct way to add the parameters would be:

cmd.Parameters.Add("@id", OleDbType.Integer).Value = idSociete;
cmd.Parameters.Add("@dtDebut", OleDbType.Date).Value = dateTraitementDebut;
cmd.Parameters.Add("@dtFin", OleDbType.Date).Value = dateTraitementFin;

By adhering to the order of parameters in the query string, the OleDbCommand object can accurately execute the query and return the desired results.

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