C# 如何检查行是否存在?
这是我在数据库表中显示/搜索记录的代码。如何验证roecord是否存在?它正在搜索成员的ID。如果记录不存在,我应该如何显示消息C# 如何检查行是否存在?,c#,sql-server,database,C#,Sql Server,Database,这是我在数据库表中显示/搜索记录的代码。如何验证roecord是否存在?它正在搜索成员的ID。如果记录不存在,我应该如何显示消息 string connectionstring = "Server=Momal-PC\\MOMAL;Database=Project;Trusted_Connection=True;"; SqlConnection conn = new SqlConnection(); conn.ConnectionString = connectionstring; con
string connectionstring = "Server=Momal-PC\\MOMAL;Database=Project;Trusted_Connection=True;";
SqlConnection conn = new SqlConnection();
conn.ConnectionString = connectionstring;
conn.Open();
SqlDataAdapter sda = new SqlDataAdapter("Select * from Members where Number = '" + SearchID.Text + "'", conn);
DataTable dtStock = new DataTable();
sda.Fill(dtStock);
dataGridView1.DataSource = dtStock;
conn.Close();
您可以这样使用:
If(dtStock.Rows.Count > 0) // If dtStock.Rows.Count == 0 then there is no rows exists.
{
// Your Logic
}
见&。如何使用数据集
和数据表。
您可以使用属性
获取此集合中DataRow对象的总数
你可以这样做
If(dtStock.Rows.Count > 0)
{
//code goes here
dataGridView1.DataSource = dtStock;
}
else
{
//Record not exists
}
这种SQL可能会快得多,因为它只向客户端返回0或1行,而不是每个匹配的行和每一列。改掉使用电脑的习惯*
SELECT 1 As X WHERE EXISTS (
Select 1 from Members where Number = '" + SearchID.Text + "')"
可以我会这样做的。非常感谢。
If(dtStock.Rows.Count > 0)
{
//code goes here
dataGridView1.DataSource = dtStock;
}
else
{
//Record not exists
}
SELECT 1 As X WHERE EXISTS (
Select 1 from Members where Number = '" + SearchID.Text + "')"
public static int RowCount()
{
string sqlConnectionString = @" Your connection string";
SqlConnection con = new SqlConnection(sqlConnectionString);
con.Open();
SqlCommand cmd = new SqlCommand("SELECT COUNT(*) AS Expr1 FROM Tablename", con);
int result = ((int)cmd.ExecuteScalar());
con.Close();
return result;
}