如何在C＃中修复SQLite查询？

Question

I try to create a datagridview query. But I have some syntax error on SQLite and I don't know how to fix my query.

        string command3 = "";
        for (int y = year1; y <= year2; y++)
        {
            if (y > year1)
            {
                command3 += " UNION ";
            }
            command3 += "SELECT 'Въведени' AS 'Въведени/Изчислени', Station AS '№ на станция', strftime('%Y',Dat) AS 'Година', 'НМ' AS 'НМ/СР/НГ', (SELECT vkolmin FROM hydmes WHERE Station= '" + comboBox1.SelectedItem.ToString() + "' and strftime('%Y',Dat) = " + y + " and strftime('%m',Dat)=01) AS 'Януари', (SELECT vkolmin FROM hydmes WHERE Station= '" + comboBox1.SelectedItem.ToString() + "' and strftime('%Y',Dat) = " + y + " and strftime('%m',Dat)=02) AS 'Февруари', (SELECT vkolmin  FROM hydmes WHERE Station= '" + comboBox1.SelectedItem.ToString() + "' and strftime('%Y',Dat) = " + y + " and strftime('%m',Dat)=03) AS 'Март', (SELECT vkolmin FROM hydmes WHERE Station= '" + comboBox1.SelectedItem.ToString() + "' and strftime('%Y',Dat) = " + y + " strftime('%m',Dat)=04) AS 'Април', (SELECT vkolmin FROM hydmes WHERE Station= '" + comboBox1.SelectedItem.ToString() + "' and strftime('%Y',Dat) = " + y + " and strftime('%m',Dat)=05) AS 'Май', (SELECT vkolmin FROM hydmes WHERE Station= '" + comboBox1.SelectedItem.ToString() + "' and strftime('%Y',Dat) = " + y + " and strftime('%m',Dat)=06) AS 'Юни', (SELECT vkolmin FROM hydmes WHERE Station= '" + comboBox1.SelectedItem.ToString() + "' and strftime('%Y',Dat) = " + y + " and strftime('%m',Dat)=07) AS 'Юли', (SELECT vkolmin FROM hydmes WHERE Station= '" + comboBox1.SelectedItem.ToString() + "' and strftime('%Y',Dat) = " + y + " and strftime('%m',Dat)=08) AS 'Август', (SELECT vkolmin FROM hydmes WHERE Station= '" + comboBox1.SelectedItem.ToString() + "' and strftime('%Y',Dat) = " + y + " and strftime('%m',Dat)=09) AS 'Септември', (SELECT vkolmin FROM hydmes WHERE Station= '" + comboBox1.SelectedItem.ToString() + "' and strftime('%Y',Dat) = " + y + " and strftime('%m',Dat)=10) AS 'Октомври', (SELECT vkolmin FROM hydmes WHERE Station= '" + comboBox1.SelectedItem.ToString() + "' and strftime('%Y',Dat) = " + y + " and strftime('%m',Dat)=11) AS 'Ноември', (SELECT vkolmin FROM hydmes WHERE Station= '" + comboBox1.SelectedItem.ToString() + "' and strftime('%Y',Dat) = " + y + " and strftime('%m',Dat)=12) AS 'Декември'"
            + "FROM hydmes WHERE Station = '" + comboBox1.SelectedItem.ToString() + "' and strftime('%Y',Dat) = " + y
            + "  UNION"
            + "  SELECT 'Изчислени', Station, strftime('%Y',Dat), 'НМ', (SELECT min(vkol) FROM hyddnev WHERE Station = '" + comboBox1.SelectedItem.ToString() + "' and strftime('%Y',Dat) = " + y + " and strftime('%m',Dat) = 01 LIMIT 1), (SELECT min(vkol) FROM hyddnev WHERE Station = '" + comboBox1.SelectedItem.ToString() + "' and strftime('%Y',Dat) = " + y + " and strftime('%m',Dat) = 02 LIMIT 1), (SELECT min(vkol) FROM hyddnev WHERE Station = '" + comboBox1.SelectedItem.ToString() + "' and strftime('%Y',Dat) = " + y + " and strftime('%m',Dat) = 03 LIMIT 1), (SELECT min(vkol) FROM hyddnev WHERE Station = '" + comboBox1.SelectedItem.ToString() + "' and strftime('%Y',Dat) = " + y + " and strftime('%m',Dat) = 04 LIMIT 1), (SELECT min(vkol) FROM hyddnev WHERE Station = '" + comboBox1.SelectedItem.ToString() + "' and strftime('%Y',Dat) = " + y + " and strftime('%m',Dat) = 05 LIMIT 1), (SELECT min(vkol) FROM hyddnev WHERE Station = '" + comboBox1.SelectedItem.ToString() + "' and strftime('%Y',Dat) = " + y + " and strftime('%m',Dat) = 06 LIMIT 1), (SELECT min(vkol) FROM hyddnev WHERE Station = '" + comboBox1.SelectedItem.ToString() + "' and strftime('%Y',Dat) = " + y + " and strftime('%m',Dat) = 07 LIMIT 1), (SELECT min(vkol) FROM hyddnev WHERE Station = '" + comboBox1.SelectedItem.ToString() + "' and strftime('%Y',Dat) = " + y + " and strftime('%m',Dat) = 08 LIMIT 1), (SELECT min(vkol) FROM hyddnev WHERE Station = '" + comboBox1.SelectedItem.ToString() + "' and strftime('%Y',Dat) = " + y + " and strftime('%m',Dat) = 09 LIMIT 1), (SELECT min(vkol) FROM hyddnev WHERE Station = '" + comboBox1.SelectedItem.ToString() + "' and strftime('%Y',Dat) = " + y + " and strftime('%m',Dat) = 10 LIMIT 1), (SELECT min(vkol) FROM hyddnev WHERE Station = '" + comboBox1.SelectedItem.ToString() + "' and strftime('%Y',Dat) = " + y + " and strftime('%m',Dat) = 11 LIMIT 1), (SELECT min(vkol) FROM hyddnev WHERE Station = '" + comboBox1.SelectedItem.ToString() + "' and strftime('%Y',Dat) = " + y + " and strftime('%m',Dat) = 12 LIMIT 1)"
            + "FROM hyddnev WHERE Station = '" + comboBox1.SelectedItem.ToString() + "' and strftime('%Y',Dat) = " + y
            + "  UNION"
            + "  SELECT 'Въведени', Station, strftime('%Y',Dat), 'СР', (SELECT vkolsre FROM hydmes WHERE Station = '" + comboBox1.SelectedItem.ToString() + "' and strftime('%Y',Dat) = " + y + " and strftime('%m',Dat) = 01), (SELECT vkolsre FROM hydmes WHERE Station = '" + comboBox1.SelectedItem.ToString() + "' and strftime('%Y',Dat) = " + y + " and strftime('%m',Dat) = 02), (SELECT vkolsre FROM hydmes WHERE Station = '" + comboBox1.SelectedItem.ToString() + "' and strftime('%Y',Dat) = " + y + " and strftime('%m',Dat) = 03), (SELECT vkolsre FROM hydmes WHERE Station = '" + comboBox1.SelectedItem.ToString() + "' and strftime('%Y',Dat) = " + y + " and strftime('%m',Dat) = 04), (SELECT vkolsre FROM hydmes WHERE Station = '" + comboBox1.SelectedItem.ToString() + "' and strftime('%Y',Dat) = " + y + " and strftime('%m',Dat) = 05), (SELECT vkolsre FROM hydmes WHERE Station = '" + comboBox1.SelectedItem.ToString() + "' and strftime('%Y',Dat) = " + y + " and strftime('%m',Dat) = 06), (SELECT vkolsre FROM hydmes WHERE Station = '" + comboBox1.SelectedItem.ToString() + "' and strftime('%Y',Dat) = " + y + " and strftime('%m',Dat) = 07), (SELECT vkolsre FROM hydmes WHERE Station = '" + comboBox1.SelectedItem.ToString() + "' and strftime('%Y',Dat) = " + y + " and strftime('%m',Dat) = 08), (SELECT vkolsre FROM hydmes WHERE Station = '" + comboBox1.SelectedItem.ToString() + "' and strftime('%Y',Dat) = " + y + " and strftime('%m',Dat) = 09), (SELECT vkolsre FROM hydmes WHERE Station = '" + comboBox1.SelectedItem.ToString() + "' and strftime('%Y',Dat) = " + y + " and strftime('%m',Dat) = 10), (SELECT vkolsre FROM hydmes WHERE Station = '" + comboBox1.SelectedItem.ToString() + "' and strftime('%Y',Dat) = " + y + " and strftime('%m',Dat) = 11), (SELECT vkolsre FROM hydmes WHERE Station = '" + comboBox1.SelectedItem.ToString() + "' and strftime('%Y',Dat) = " + y + " and strftime('%m',Dat) = 12)"
            + "FROM hydmes WHERE Station = '" + comboBox1.SelectedItem.ToString() + "' and strftime('%Y',Dat) = " + y
            + "  UNION"
            + "  SELECT 'Изчислени', Station, strftime('%Y',Dat), 'СР', (SELECT avg(vkol) FROM hyddnev WHERE Station = '" + comboBox1.SelectedItem.ToString() + "' and strftime('%Y',Dat) = " + y + " and strftime('%m',Dat) = 01 LIMIT 1), (SELECT avg(vkol) FROM hyddnev WHERE Station = '" + comboBox1.SelectedItem.ToString() + "' and strftime('%Y',Dat) = " + y + " and strftime('%m',Dat) = 02 LIMIT 1), (SELECT avg(vkol) FROM hyddnev WHERE Station = '" + comboBox1.SelectedItem.ToString() + "' and strftime('%Y',Dat) = " + y + " and strftime('%m',Dat) = 03 LIMIT 1), (SELECT avg(vkol) FROM hyddnev WHERE Station = '" + comboBox1.SelectedItem.ToString() + "' and strftime('%Y',Dat) = " + y + " and strftime('%m',Dat) = 04 LIMIT 1), (SELECT avg(vkol) FROM hyddnev WHERE Station = '" + comboBox1.SelectedItem.ToString() + "' and strftime('%Y',Dat) = " + y + " and strftime('%m',Dat) = 05 LIMIT 1), (SELECT avg(vkol) FROM hyddnev WHERE Station = '" + comboBox1.SelectedItem.ToString() + "' and strftime('%Y',Dat) = " + y + " and strftime('%m',Dat) = 06 LIMIT 1), (SELECT avg(vkol) FROM hyddnev WHERE Station = '" + comboBox1.SelectedItem.ToString() + "' and strftime('%Y',Dat) = " + y + " and strftime('%m',Dat) = 07 LIMIT 1), (SELECT avg(vkol) FROM hyddnev WHERE Station = '" + comboBox1.SelectedItem.ToString() + "' and strftime('%Y',Dat) = " + y + " and strftime('%m',Dat) = 08 LIMIT 1), (SELECT avg(vkol) FROM hyddnev WHERE Station = '" + comboBox1.SelectedItem.ToString() + "' and strftime('%Y',Dat) = " + y + " and strftime('%m',Dat) = 09 LIMIT 1), (SELECT avg(vkol) FROM hyddnev WHERE Station = '" + comboBox1.SelectedItem.ToString() + "' and strftime('%Y',Dat) = " + y + " and strftime('%m',Dat) = 10 LIMIT 1), (SELECT avg(vkol) FROM hyddnev WHERE Station = '" + comboBox1.SelectedItem.ToString() + "' and strftime('%Y',Dat) = " + y + " and strftime('%m',Dat) = 11 LIMIT 1), (SELECT avg(vkol) FROM hyddnev WHERE Station = '" + comboBox1.SelectedItem.ToString() + "' and strftime('%Y',Dat) = " + y + " and strftime('%m',Dat) = 12 LIMIT 1)"
            + "FROM hyddnev WHERE Station = '" + comboBox1.SelectedItem.ToString() + "' and strftime('%Y',Dat) = " + y
            + "  UNION"
            + "  SELECT 'Въведени', Station, strftime('%Y',Dat), 'НГ', (SELECT vkolmax FROM hydmes WHERE Station = '" + comboBox1.SelectedItem.ToString() + "' and strftime('%Y',Dat) = " + y + " and strftime('%m',Dat) = 01), (SELECT vkolmax FROM hydmes WHERE Station = '" + comboBox1.SelectedItem.ToString() + "' and strftime('%Y',Dat) = " + y + " and strftime('%m',Dat) = 02), (SELECT vkolmax FROM hydmes WHERE Station = '" + comboBox1.SelectedItem.ToString() + "' and strftime('%Y',Dat) = " + y + " and strftime('%m',Dat) = 3), (SELECT vkolmax FROM hydmes WHERE Station = '" + comboBox1.SelectedItem.ToString() + "' and strftime('%Y',Dat) = " + y + " and strftime('%m',Dat) = 04), (SELECT vkolmax FROM hydmes WHERE Station = '" + comboBox1.SelectedItem.ToString() + "' and strftime('%Y',Dat) = " + y + " and strftime('%m',Dat) = 05), (SELECT vkolmax FROM hydmes WHERE Station = '" + comboBox1.SelectedItem.ToString() + "' and strftime('%Y',Dat) = " + y + " and strftime('%m',Dat) = 06), (SELECT vkolmax FROM hydmes WHERE Station = '" + comboBox1.SelectedItem.ToString() + "' and strftime('%Y',Dat) = " + y + " and strftime('%m',Dat) = 07), (SELECT vkolmax FROM hydmes WHERE Station = '" + comboBox1.SelectedItem.ToString() + "' and strftime('%Y',Dat) = " + y + " and strftime('%m',Dat) = 08), (SELECT vkolmax FROM hydmes WHERE Station = '" + comboBox1.SelectedItem.ToString() + "' and strftime('%Y',Dat) = " + y + " and strftime('%m',Dat) = 09), (SELECT vkolmax FROM hydmes WHERE Station = '" + comboBox1.SelectedItem.ToString() + "' and strftime('%Y',Dat) = " + y + " and strftime('%m',Dat) = 10), (SELECT vkolmax FROM hydmes WHERE Station = '" + comboBox1.SelectedItem.ToString() + "' and strftime('%Y',Dat) = " + y + " and strftime('%m',Dat) = 11), (SELECT vkolmax FROM hydmes WHERE Station = '" + comboBox1.SelectedItem.ToString() + "' and strftime('%Y',Dat) = " + y + " and strftime('%m',Dat) = 12)"
            + "FROM hydmes WHERE Station = '" + comboBox1.SelectedItem.ToString() + "' and strftime('%Y',Dat) = " + y
            + "  UNION"
            + "  SELECT 'Изчислени', Station, strftime('%Y',Dat), 'НГ', (SELECT max(vkol) FROM hyddnev WHERE Station = '" + comboBox1.SelectedItem.ToString() + "' and strftime('%Y',Dat) = " + y + " and strftime('%m',Dat) = 01 LIMIT 1), (SELECT max(vkol) FROM hyddnev WHERE Station = '" + comboBox1.SelectedItem.ToString() + "' and strftime('%Y',Dat) = " + y + " and strftime('%m',Dat) = 02 LIMIT 1), (SELECT max(vkol) FROM hyddnev WHERE Station = '" + comboBox1.SelectedItem.ToString() + "' and strftime('%Y',Dat) = " + y + " and strftime('%m',Dat) = 03 LIMIT 1), (SELECT max(vkol) FROM hyddnev WHERE Station = '" + comboBox1.SelectedItem.ToString() + "' and strftime('%Y',Dat) = " + y + " and strftime('%m',Dat) = 04 LIMIT 1), (SELECT max(vkol) FROM hyddnev WHERE Station = '" + comboBox1.SelectedItem.ToString() + "' and strftime('%Y',Dat) = " + y + " and strftime('%m',Dat) = 05 LIMIT 1), (SELECT max(vkol) FROM hyddnev WHERE Station = '" + comboBox1.SelectedItem.ToString() + "' and strftime('%Y',Dat) = " + y + " and strftime('%m',Dat) = 06 LIMIT 1), (SELECT max(vkol) FROM hyddnev WHERE Station = '" + comboBox1.SelectedItem.ToString() + "' and strftime('%Y',Dat) = " + y + " and strftime('%m',Dat) = 07 LIMIT 1), (SELECT max(vkol) FROM hyddnev WHERE Station = '" + comboBox1.SelectedItem.ToString() + "' and strftime('%Y',Dat) = " + y + " and strftime('%m',Dat) = 08 LIMIT 1), (SELECT max(vkol) FROM hyddnev WHERE Station = '" + comboBox1.SelectedItem.ToString() + "' and strftime('%Y',Dat) = " + y + " and strftime('%m',Dat) = 09 LIMIT 1), (SELECT max(vkol) FROM hyddnev WHERE Station = '" + comboBox1.SelectedItem.ToString() + "' and strftime('%Y',Dat) = " + y + " and strftime('%m',Dat) = 10 LIMIT 1), (SELECT max(vkol) FROM hyddnev WHERE Station = '" + comboBox1.SelectedItem.ToString() + "' and strftime('%Y',Dat) = " + y + " and strftime('%m',Dat) = 11 LIMIT 1), (SELECT max(vkol) FROM hyddnev WHERE Station = '" + comboBox1.SelectedItem.ToString() + "' and strftime('%Y',Dat) = " + y + " and strftime('%m',Dat) = 12 LIMIT 1)"
            + "FROM hyddnev WHERE Station = '" + comboBox1.SelectedItem.ToString() + "' and strftime('%Y',Dat) = " + y;
        }
        command3 += "  group by strftime('%Y',Dat)";

        SQLiteDataAdapter insertDat3 = new SQLiteDataAdapter(command3, Connection);
            using (DataTable dt3 = new DataTable())
            {
                insertDat3.Fill(dt3);
                dataGridView1.DataSource = dt3.DefaultView;
            }

        }

Error is:

System.Data.SQLite.SQLiteException (0x80004005): SQL logic error or missing database near "strftime": syntax error

I have the same application who work with MySql database and just copy this query from other application but SQLite syntax is different than MySQL ?

I don't know where and how I can fix the query.

Answer 1

Sorry, I can't comment yet so I'll post this as an answer.

First, I agree with the comments above. It's hard to help you with your problem with just the sample code you provided. Second, don't directly concatenate strings to your queries because there's a risk of SQL injection.

With that being said, I've had a few situations like this myself and my approach is to debug/test my queries directly in a query window. I suggest that you separate your queries, "joined" by those UNIONs, provide actual values to them and run them one by one. If all works fine, run the queries altogether. If everything works, then the problem must be in your concatenation. I always like to approach my problem the "divide-and-conquer" way, I like to separate and eliminate possible causes.