Error out parameter must be assigned before control leave cu

Question

Problem
Error out parameter must be assigned before control leave current method .
function GetInsertStatmentText below return full insert statement as below

INSERT INTO master_table(id, branch_id, name, address, phone) VALUES(@id, @branch_id, @name, @address, @phone);

in out paramter i need to return

@id, @branch_id, @name, @address, @phone

when i add out parameter to function i get error :

 

Error out parameter must be assigned before control leave current method
 

How to solve this error please ?

What I have tried:

public static string GetInsertStatmentText(string JsonData,out  sqp)
        {
            string Insert = "";
            JObject jo = JObject.Parse(JsonData);
            JToken m = jo["master"];
            string connectionstring = "Server=AHMEDSALAH-PC\\SQL2014;Database=Atum;User Id=sa;Password=abc123;"; //change connection string
            using (SqlConnection connection = new SqlConnection(connectionstring))
            {
                using (SqlCommand command = new SqlCommand(JsonHelper.GetInsertStatement(m), connection))
                {
                    connection.Open();
                    List<SqlParameter> lsp = JsonHelper.GetSqlParams(jo["master"]);
                    foreach (SqlParameter sqp in lsp)
                        command.Parameters.Add(sqp);
                    Insert = command.CommandText;
                }
            }
            return Insert;

        }