使用来自两个不同表的两个 SELECT 语句

Question

我目前正在使用 Dapper 将 Sql 服务器中的数据显示到文本框中。我有这两张表：

id | fname | lname  | Age
 1 | cal   | bla    | 100
 2 | vin   | bla    | 10

表1

id | fname | lname | Age
1 | cal   | vin    | 50
2 | calvin | cal    | 25

表2

我的存储过程如下所示：

@Fname nvarchar(50)
AS
BEGIN
SELECT Fname,Lname,Age FROM table1 WHERE Fname=@Fname 
UNION
SELECT Fname,Lname,Age FROM table2 WHERE Fname=@Fname
END

我在文本框中的表单中插入名字，它将显示 lname 和年龄。我希望生成的表包含 table1 中的 lname 和 table2 中的年龄，如下所示：

id | fname | lname  | Age
1 | calvin | bla    | 50

我的 C# 函数：

   public void Multi(String name)
    {
        try
        {
            using (IDbConnection db = new SqlConnection(ConfigurationManager.ConnectionStrings["SqlConnectionString"].ConnectionString))
            {
                if (db.State != ConnectionState.Open)
                    db.Open();

                DynamicParameters p = new DynamicParameters();
                SqlCommand command = new SqlCommand("multi", con);
                p.Add("@Fname", tb2.Text, 
                DbType.String,ParameterDirection.Input);

                var multi = con.QueryMultiple("multi", p, commandType: 
                CommandType.StoredProcedure);
                clients cls = new clients();
                cls.C = multi.Read<Client>().ToList();
                var cli = multi.Read<clients>().ToList();
                SqlDataReader reader = command.ExecuteReader();
                while (reader.Read())
                {
                    cls.C.Add(new Client()
                    {
                        Fname = (String)reader["Fname"],
                        Lname = (String)reader["Lname"],
                        Age = (int)reader["Age"]
                    });
                    tb2.Text = cls.C[0].Fname;
                    tb3.Text = cls.C[0].Lname;
                    tb4.Text = cls.C[0].Age.ToString();

和客户端类：

    class Client
    {
    public string Fname { get; set; }
    public string Lname { get; set; }
    public int Age { get; set; }
     }
    class clients
    {
     public List<Client> C = new List<Client>();
    }

我收到以下错误：

1-Procedure or function 'multi' expects parameter '@Fname', which was not 
supplied.
2-The reader has been disposed; this can happen after all data has been 
consumed Object name: 'Dapper.SqlMapper+GridReader'.
3- An explicit value for the identity column in table 'CloneInfo' can only 
be specified when a column list is used and IDENTITY_INSERT is ON.

我将光标指向 reader，它显示为 null，执行中断

回答： 我已经添加了这个，它工作得很好：

    DynamicParameters p = new DynamicParameters();
                p.Add("@Fname", tb2.Text);
                var multi = con.QueryMultiple("multi", p, commandType: CommandType.StoredProcedure);

                clients cls = new clients();
                clients cls2 = new clients();

                cls.C = multi.Read<Client>().ToList();
                cls2.C = multi.Read<Client>().ToList();

                tb2.Text = cls.C[0].Fname;
                tb3.Text = cls.C[0].Lname;
                tb4.Text = cls2.C[0].Age.ToString();

                if (db.State != ConnectionState.Closed)
                    db.Close();.C[0].Age.ToString();

Answer 1

使用下面的sql：

@Fname nvarchar(50)
AS
BEGIN
if ((select count(*) from table1 where Fname=@Fname) > 0)
begin
  select t1.Fname, t1.Lname, t2.Age
  from table1 as t1
  left join table2 as t2 on t1.Fname == t2.Fname
  where t1.Fname = @Fname
end
else
begin
  select t2.Fname, t1.Lname, t2.Age
  from table2 as t2
  left join table1 as t1 on t2.Fname == t1.Fname
  where t2.Fname = @Fname
end