Question

I am writing a C# WPF application with controls bound to a MySQL 5.5 database. I’m populating a DataTable using a MySqlDataAdapter, passing in a MySQL SELECT query.

When the query is something trivial, like SELECT * FROM People or SELECT LastName, FirstName, PersonID FROM People, all is well and my ListBox control ends up populated with the expected names.

When the query contains a fairly simple CONCAT operator, though, the query silently fails and the ListBox stays empty. In particular neither of the following have worked, even though both work fine from within the MySQL command line.

SELECT CONCAT(LastName, FirstName) as Name FROM People
SELECT CAST(CONCAT(LastName, FirstName) AS CHAR) as Name FROM People

Both LastName and FirstName are defined as VARCHAR. So, I wouldn’t expect this to be an instance of CONCAT returning a binary string in any case. I mention that because it appears to have been the problem for similar issues that other folks have mentioned.

Answer 1

I’d imagine the DataAdapter attempts to parse your query into an internal format so that it can do things like generate Update and Insert commands.

Can you fill your datatable using a MySqlDataReader instead? This is probably only helpful if you are not planning to do database updates with the DataTable

Going from memory…

MySqlCommand cmd = new MySqlCommand(query, connection);
MySqlDataReader reader = cmd.ExecuteReader();
DataTable dt = new DataTable();
dt.Load(reader);