![](/img/trans.png)
[英]select two columns from two different tables in the same db using mysql + use the output of query in C#
[英]Using two SELECT statements from two different tables
我目前正在与Dapper合作,以将来自Sql Server的数据显示到文本框中。 我有这两个表:
id | fname | lname | Age
1 | cal | bla | 100
2 | vin | bla | 10
表格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,它将显示名称和年龄。 我希望结果表包括来自table1的lname和来自table2的age,类似这样:
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>();
}
我收到这些错误:
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.
我将光标指向读者 ,它说为空,执行中断
答案:Ive添加了它,它可以完美地工作:
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();
使用以下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
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.