c#-检查数据库中的重复值
作者:互联网
在将TextBox中的值保存到数据库中之前,我需要检查该值是否已存在于数据库中.
这是TextBox代码:
<tr>
<td>
<asp:Label ID="lblProductConstruction" runat="server" Text="Product Construction:" Font-Names="Open Sans"></asp:Label></td>
<td>
<asp:TextBox ID="txtProductConstruction" runat="server" Font-Names="Merriweather" margin-Left="100px" ></asp:TextBox><br />
</td>
</tr>
<tr>
保存按钮:
<input type="button" class="button" id="myButton" value="Save"/>
在按钮上单击Ajax:
$(function () {
$('#myButton').on('click', function () {
var lvl = $('#MainContent_txtProductConstruction').val()
$.ajax({
type: "POST",
url: "NewProductConstruction.aspx/GetCollection",
data: JSON.stringify({'lvl': lvl }),
contentType: "application/json; charset=utf-8",
dataType: "json",
success: function (response) {
alert("Saved successfully.");
console.log(response);
location.reload(true);
},
error: function (response) {
alert("Not Saved!");
console.log(response);
location.reload(true);
}
});
});
});
WebMethod接收值并将该参数(@LvlName)发送到数据库:
[WebMethod(EnableSession = true)]
public static void GetCollection(string lvl)
{
//string strMsg = "";
string conn = ConfigurationManager.ConnectionStrings["Connection"].ConnectionString;
using (SqlConnection connection = new SqlConnection(conn))
try
{
connection.Open();
SqlCommand cmdProc = new SqlCommand("InsertLvlName", connection);
cmdProc.CommandType = CommandType.StoredProcedure;
cmdProc.Parameters.AddWithValue("@LvlName", lvl);
cmdProc.ExecuteNonQuery();
//strMsg = "Saved successfully.";
}
catch
{
}
finally
{
connection.Close();
}
return;
}
我需要帮助检查两件事:
1)要查看文本框是否为空,如果是这种情况,请不要将该值保存到数据库中,并显示警报此字段需要某种值.
2)我需要某种检查,如果数据库中已经存在相同字段的值,则不要保存它.
提前致谢 !
解决方法:
这是我们可以使用jquery进行的简单验证
if (inp.val().length > 0) {
//do something
}
else
{
alert("Enter Value")
}
完整示例:-
$(function () {
$('#myButton').on('click', function () {
var lvl = $('#MainContent_txtProductConstruction').val()
if(lvl.length>0)
{
$.ajax({
type: "POST",
url: "NewProductConstruction.aspx/GetCollection",
data: JSON.stringify({'lvl': lvl }),
contentType: "application/json; charset=utf-8",
dataType: "json",
success: function (response) {
alert("Saved successfully.");
console.log(response);
location.reload(true);
},
error: function (response) {
alert("Not Saved!");
console.log(response);
location.reload(true);
}
});
}
else
{
alert("Please enter Value")
}
});
});
第二部分:-
SqlCommand checkvalue = new SqlCommand("SELECT COUNT(*) FROM [TableName] WHERE ([ColumnNameUser] = @user)" , connection);
checkvalue.Parameters.AddWithValue("@user", lvl);
int UserExist = (int)checkvalue.ExecuteScalar();
if(UserExist > 0)
{
//Username exist
}
else
{
//Username doesn't exist.
}
如果您想让Sp检查,则:-
根据您的姓名和字段名称进行编辑.
CREATE PROCEDURE InsertName
(
@username varchar(25),
@userpassword varchar(25)
)
AS
IF EXISTS(SELECT 'True' FROM MyTable WHERE username = @username)
BEGIN
--This means it exists, return it to ASP and tell us
SELECT 'This record already exists!'
END
ELSE
BEGIN
--This means the record isn't in there already, let's go ahead and add it
SELECT 'Record Added'
INSERT into MyTable(username, userpassword) VALUES(@username, @userpassword)
END
标签:webmethod,ajax,insert-update,c,jquery 来源: https://codeday.me/bug/20191025/1925955.html