Can't Figure Out Missing Parameter Error When Running an Oracle Query

Question

I am very new to database queries and even more so, Oracle. I am also new to development work and, believe it or not, am creating this an for work purely out of frustration with the current process. Anyway, I am attempting to collect input from a multi-line text box and run a query. Each line corresponds to a single string that needs to be passed into the WHERE statement and the results will be dumped into a data table. Unfortunately, Oracle has still not released its developer tools for VS2019 so I am having to do this the harder way.

UPDATE # 2: I have completely rebuilt the query since it was not running even when using known working code from another query. Below is what I have pieced together from various places on the interwebs. While debugging, it appears to parse and format the text correctly and pass it into the OracleParameter without issue. I am getting a Missing Expression error but I don't know what I am missing.

var connString = 
ConfigurationManager.ConnectionStrings["dB"].ConnectionString;
string query = "SELECT col1, col2, col3, col4 FROM table WHERE col5 IN (";

using (OracleConnection conn = new OracleConnection(connString))
         try
         {
            var input = "";
            input = uniLookup.UniList;
            var uniList = string.Join(",", Regex.Split(input, @"(?:\r\n|\n|\r)"));

            string allParams = uniList;
            string formattedParams = allParams.Replace(" ", string.Empty);
            string[] splitParams = formattedParams.Split(',');

            List<OracleParameter> parameters = new List<OracleParameter>();

            using (OracleCommand cmd = new OracleCommand(query, conn))
            {
                for (int i = 0; i < splitParams.Length; i++)
                {
                    query += @":Uni" + i + ",";
                    parameters.Add(new OracleParameter(":Uni" + i, splitParams[i]));
                    {
                        query = query.Substring(0, (query.Length - 1));
                        query += ')';
                        conn.Open();
                        using (OracleDataReader reader = cmd.ExecuteReader())  <==ERROR
                        {
                            if (!reader.HasRows)
                            {
                                while (reader.Read())
                                {
                                    reader.Read();
                                    {
                                        MessageBox.Show(reader.GetString(1));
                                    }
                                }
                            }

Answer 1

You can use IN in your where clause in this way to get rows from multiple values as: string query = "SELECT dummyCol FROM dummytable WHERE altCol IN ("+text+");";

where you just have to change your text as text="'value1','value2','value3'"; this will not produce any syntax error. You can convert your multi line text into same comma separated values using this :

            foreach (String s in textBox1.Text.Split('\n'))
            {
                text +="'"+ s+"',";
            }
            text = text.TrimEnd(',');

this will help you achieve what you need. you can ask If there is any confusion.

Your final code will become :

public void GetData()
        {
            if (string.IsNullOrWhiteSpace(textbox1.Text) || textbox1.Text == "")
            {
                MessageBox.Show("Please Enter at least 1 Value and Try Again!");
            }
            else
            {
                System.Data.DataTable dt = new System.Data.DataTable();
                // string[] lines = textbox1.Text.Split('\n');


                string text = "";
                foreach (String s in textBox1.Text.Split('\n'))
                {
                    text += "'" + s + "',";
                }
                text = text.TrimEnd(',');

                //Connection Credentials
                string credentials = "Credentials";
                string query = "SELECT dummyCol FROM dummytable WHERE altCol IN ("+text+");";

                OracleConnection conn = new OracleConnection(credentials);

                try
                {
                    //Open The Connection
                    conn.Open();
                    using (OracleCommand cmd = new OracleCommand(query, conn))
                    {
                        //Call the Oracle Reader
                        using (OracleDataReader reader = cmd.ExecuteReader())
                        {
                            if (!reader.HasRows)
                            {
                                MessageBox.Show("Unable to Retrieve Data");
                                return;
                            }
                            else if (reader.HasRows)
                            {
                                reader.Read();
                                DataRow row = dt.NewRow();
                                // create variables to accept reader data for each column
                                // insert data from query into each column here
                                dt.Rows.Add(row);
                            }
                        }
                    }
                }
         }

        }