How to pass a list of values as parameter in c# databinding

Question

I've got an Asp.Net application with a MySql database. To access this database I use a dataset (.xsd) where I've put my queries in TableAdapters. One of these queries has a WHERE IN clause, like:

SELECT somefield
FROM sometable
WHERE somefield IN (?)

This somefield is a string value. The TableAdapter function expects a string parameter to replace the query parameter. However, I would like to pass a List<string> (or an array, or any other type) to check for multiple values. The only way I've found so far is to convert the list into a comma separeted list:

GetData(string.Join(",", myList.ToArray());

It works fine as long as there's only one value in the list. With two values the query returns 0 rows. I activated the general log in MySql and found out it has to do with quotes. The query that reaches the database is:

SELECT somefield
FROM sometable
WHERE somefield IN ('foo,bar')

I added extra quotes when joining the values:

GetData(string.Join("','", myList.ToArray());

But the extra quotes only get escaped and the result still is 0 rows:

SELECT somefield
FROM sometable
WHERE somefield IN ('foo\',\'bar')

Right now the only option I see is converting every single string into an id and join these integers into a string. Like in this thread. But this means a lot of extra calls to the database to get those id's. I really prefer to use the string values!

Who knows how to solve this puzzle?

Answer 1

TableAdapter will keep escaping quotes. You could make a user defined function, which takes a comma-delimited argument and returns it as rows. This way you can access the function as follows. I did this with T-SQL before. It should be doable in MySQL.

SELECT somefield
FROM sometable
WHERE somefield IN UDFDelimitedToRows(?)

Answer 2

Try this:

GetData(String.Format("'{0}'", String.Join(",", myList.ToArray()));

If the single quotes get escaped, double them, such as:

GetData(String.Format("''{0}''", String.Join(",", myList.ToArray()));