conn.Open(); string Checksql = "select 用户名 from TableUserInform "; int tag = 0; string xx = null; SqlCommand checkcmd = new SqlCommand(Checksql, conn); SqlDataReader dr = checkcmd.ExecuteReader();
while (dr.Read()) {
xx = dr["用户名"].ToString();
if (xx == querystring) { tag = 1; break; } } if (querystring != ""&&querystring!=null) { if (tag == 1) { Response.Write("<b style='color=red'>!用户名已存在</b>"); } else if (tag == 0) { Response.Write("<b style='color=green'>√用户名可注册</b>"); ///插入数据库; } } else { Response.Write("<b style='color=yellow'>请输入用户名</b>"); } conn.Close();
conn.Open(); string Checksql = "select 用户名 from TableUserInform "; int tag = 0; string xx = null; SqlCommand checkcmd = new SqlCommand(Checksql, conn); SqlDataReader dr = checkcmd.ExecuteReader();
while (dr.Read()) {
xx = dr["用户名"].ToString();
if (xx == querystring) { tag = 1; break; } } if (querystring != ""&&querystring!=null) { if (tag == 1) { Response.Write("<b style='color=red'>!用户名已存在</b>"); } else if (tag == 0) { Response.Write("<b style='color=green'>√用户名可注册</b>"); ///插入数据库; } } else { Response.Write("<b style='color=yellow'>请输入用户名</b>"); } conn.Close();
后台代码什么的都有了,取到的值也为空了,就是判断出了问题? var tet=bmm.GetWorkCodeOne(txtWorkCode.Text); if (tet == null) { MessageBox.Show("请输入正确的运编号!"); return; } 这个IF怎么写啊,谢谢了!
连接字符串在web.config中配置 string connectString = ConfigurationManager.ConnectionStrings["数据库连接"].ConnectionString; SqlConnection conn = new SqlConnection(connectString); public void TableSelect() { conn.Open(); string condition5=textbox.Text; string selectStr = "select count(*) from TableUserInform where 用户名='" + condition5 + "'"; SqlCommand cmd = new SqlCommand(selectStr, conn); string tag=cmd.ExecuteScalar().ToString(); Response.Write("找到的匹配项为:" + tag + "项"); conn.Close(); }
SqlConnection conn = new SqlConnection("server=127.0.0.1;database=testdb;uid=sa;pwd=123"); conn.Open(); string sql="select count(*) from test_tb where textbox='"+TextBox1.Text+"'"; SqlCommand cmd = new SqlCommand(sql, conn); int k=Convert.ToInt32(cmd.ExecuteScalar()) if(k>0) { MessageBox.show("数据库的值已经存在"); } else { MessageBox.show("数据库的值bu存在"); }
string str=this.文本框名字.text;根据文本框的名字(str)去数据库对应的表查嘛、
{
MessageBox.Show("请先输入需要修改信息的运编号!");
return;
}
ModifyEditForm mef = new ModifyEditForm(txtWorkCode.Text.ToUpper());
mef.ShowDialog();
if (mef.DialogResult == DialogResult.OK)
{
BindGrid();
}
我想把这个ModifyEditForm mef = new ModifyEditForm(txtWorkCode.Text.ToUpper());
判断一下是否存在.如果不存在就不能跳转!
要判断数据在数据库库是否存在:
首先,你要获取文本框的内容(因为你要对比嘛)
其次,要把这个字符串的值与数据库比对(所以你要写SQL语句)
最后,根据数据库比对结果看返回值(因为你向数据库查询,必须得知道有没有呀)
然后判断DataSet的DataTable的Columns里有没有该字段。
遇到和楼主一样问题,我把自己的笨蛋代码贴上来可以 参考下:
string querystring = Request["UserName"].ToString();
querystring = Server.UrlDecode(querystring);
string connectString = ConfigurationManager.ConnectionStrings["数据库连接"].ConnectionString;
SqlConnection conn = new SqlConnection(connectString); try
{
conn.Open();
conn.Close(); }
catch (SqlException ee)
{
Response.Write(ee.Message.ToString()); }
conn.Open();
string Checksql = "select 用户名 from TableUserInform ";
int tag = 0;
string xx = null;
SqlCommand checkcmd = new SqlCommand(Checksql, conn);
SqlDataReader dr = checkcmd.ExecuteReader();
while (dr.Read())
{
xx = dr["用户名"].ToString();
if (xx == querystring)
{ tag = 1;
break;
}
}
if (querystring != ""&&querystring!=null)
{ if (tag == 1)
{
Response.Write("<b style='color=red'>!用户名已存在</b>"); }
else if (tag == 0)
{
Response.Write("<b style='color=green'>√用户名可注册</b>");
///插入数据库;
}
}
else
{
Response.Write("<b style='color=yellow'>请输入用户名</b>");
}
conn.Close();
遇到和楼主一样问题,我把自己的笨蛋代码贴上来可以 参考下:
string querystring = Request["UserName"].ToString();
querystring = Server.UrlDecode(querystring);
string connectString = ConfigurationManager.ConnectionStrings["数据库连接"].ConnectionString;
SqlConnection conn = new SqlConnection(connectString); try
{
conn.Open();
conn.Close(); }
catch (SqlException ee)
{
Response.Write(ee.Message.ToString()); }
conn.Open();
string Checksql = "select 用户名 from TableUserInform ";
int tag = 0;
string xx = null;
SqlCommand checkcmd = new SqlCommand(Checksql, conn);
SqlDataReader dr = checkcmd.ExecuteReader();
while (dr.Read())
{
xx = dr["用户名"].ToString();
if (xx == querystring)
{ tag = 1;
break;
}
}
if (querystring != ""&&querystring!=null)
{ if (tag == 1)
{
Response.Write("<b style='color=red'>!用户名已存在</b>"); }
else if (tag == 0)
{
Response.Write("<b style='color=green'>√用户名可注册</b>");
///插入数据库;
}
}
else
{
Response.Write("<b style='color=yellow'>请输入用户名</b>");
}
conn.Close();
var tet=bmm.GetWorkCodeOne(txtWorkCode.Text);
if (tet == null)
{
MessageBox.Show("请输入正确的运编号!");
return;
}
这个IF怎么写啊,谢谢了!
string connectString = ConfigurationManager.ConnectionStrings["数据库连接"].ConnectionString;
SqlConnection conn = new SqlConnection(connectString);
public void TableSelect()
{
conn.Open();
string condition5=textbox.Text;
string selectStr = "select count(*) from TableUserInform where 用户名='" + condition5 + "'";
SqlCommand cmd = new SqlCommand(selectStr, conn); string tag=cmd.ExecuteScalar().ToString();
Response.Write("找到的匹配项为:" + tag + "项");
conn.Close();
}
SqlConnection conn = new SqlConnection("server=127.0.0.1;database=testdb;uid=sa;pwd=123");
conn.Open();
string sql="select count(*) from test_tb where textbox='"+TextBox1.Text+"'";
SqlCommand cmd = new SqlCommand(sql, conn);
int k=Convert.ToInt32(cmd.ExecuteScalar())
if(k>0)
{
MessageBox.show("数据库的值已经存在");
}
else
{
MessageBox.show("数据库的值bu存在");
}