C#•2y ago

✅ PostgreSQL foreach() insert not working

Hey, currently working on a DB project for the first time with PostgreSQL and for some reason this insert operation inserts the first entry in the list for the length of the list into the DB resulting in mass duplicate entries of just the first entry of the list.

var sql = @"INSERT INTO outstanding(name) VALUES(@name)";
            using var cmd = new NpgsqlCommand(sql, con);
            foreach (var item in outstanding)
            {
                cmd.Parameters.AddWithValue("name",item);
                cmd.Prepare();
                cmd.ExecuteNonQuery();
            }

var sql = @"INSERT INTO outstanding(name) VALUES(@name)";
            using var cmd = new NpgsqlCommand(sql, con);
            foreach (var item in outstanding)
            {
                cmd.Parameters.AddWithValue("name",item);
                cmd.Prepare();
                cmd.ExecuteNonQuery();
            }

What did I miss? TYIA

8 Replies

Unknown User•2y ago

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Jona4Play•2y ago

This might be true but your suggested change below for testing didn't work either. Prepare() seems to be a command to speed up future repetitions of a command by holding it in cache and just waiting the value from the program and not the whole string.

Jona4Play•2y ago

Here is a picture of what the DB looks like as it might be a bit unclear because of my description. The List I provided consisted of 6 unique links

Unknown User•2y ago

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Jona4Play•2y ago

You're right. This works. But still a bit weird I feel. Anyways, huge thanks for saving me a ton of time. Have a lovely day 😄

Unknown User•2y ago

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Jona4Play•2y ago

Nice. Thank you

Accord•2y ago

Was this issue resolved? If so, run /close - otherwise I will mark this as stale and this post will be archived until there is new activity. Closed!

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✅ PostgreSQL foreach() insert not working