I've an sql table. I've also a list in my Asp.Net code (C#).
public static List listColumns = new List();
And listColumns contains 1,2,3...10 randomly. For example it can contains 1, 5, 6, 9. I want to make a query with this conditions. So, If the list has these values, my query should be:
SELECT * FROM Table WHERE id=1 or id=5 or id=6 or id=9
The listColumns may contains different values and has different counts. How can I do this query regularly?
Here is a solution without a for loop, but unfortunately also without a parameterized SQL statement:
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
public class test {
public static void Main(string[] args)
{
//List<int> listColumns = new List<int>(){ 1, 5, 6, 9};
System.Collections.Generic.List<int> listColumns = new System.Collections.Generic.List<int>(){ 1, 5, 6, 9};
string s = String.Join(", ", listColumns.Select(x => x.ToString()));
string sql = String.Format("SELECT * FROM Table WHERE ID IN ({0})", s);
Console.WriteLine(sql);
}
}
Please note that using select * is considered as a bad practice
edit Here is some new code because your list is of type System.Web.UI.MobileControls.List
string sql = String.Format("SELECT * FROM Table WHERE ID IN ({0})",
listColumns.ListItem.Value);
edit 2 I have taken the code from your comment:
list.Items.Clear();
string values = DropDownList4.SelectedValue;
string[] words = values.Split(',');
foreach (string s in words)
if (s != "" && s != string.Empty && s != null)
list.Items.Add(s);
I guess that you have this on the dropdown changed event or something? and your dropdown has a string like "1,5,6,9" in the value. If all my assumptions are correct you can use:
System.Collections.Generic.List<int> selectedValues = new System.Collections.Generic.List<int>();
foreach (string s in words)
if (!String.IsNullOrWhiteSpace(s))
selectedValues.Add(Convert.ToInt32(s));
string ids = String.Join(", ", selectedValues.Select(x => x.ToString()));
string sql = String.Format("SELECT * FROM Table WHERE ID IN ({0})", ids);
MobileControls but of System.Collections.Generic.List msdn.microsoft.com/en-us/library/6sh2ey19%28v=vs.110%29.aspxThe System.Web.Mobile.dll assembly has been deprecated and should no longer be used. For information about how to develop ASP.NET mobile applications, see http://go.microsoft.com/fwlink/?LinkId=157231 msdn.microsoft.com/en-us/library/… //assume a list of int value name listColumns
var listColumns = new List<int>() { 1, 5, 9 };
var sb = new StringBuilder();
sb.Append("SELECT * FROM Table");
for (int i = 0; i < listColumns.Count; i++)
{
if (i == 0)
{
sb.Append(" where ");
sb.Append(" id=" + listColumns[i]);
}
else
sb.Append(" or id=" + listColumns[i]);
}
Console.Write(sb.ToString());
pass query variable to sqlcommand
StringBuilder for string concatenation in a loop and secondly, I would prefer the use of parameters when building a SQL statement.//assume input is List of integers
List<int> ids = new List<int> { 1,5,6,9 };
//build your SQL statement as below
string cmdText = "SELECT * FROM Table WHERE id IN ({0})";
// add parameters for each id value
string[] paramNames = ids.Select(
(s, i) => "@id" + i.ToString()
).ToArray();
string inClause = string.Join(",", paramNames);
//set the parameter values
using (SqlCommand cmd = new SqlCommand(string.Format(cmdText, inClause))) {
for(int i = 0; i < ids.Count; i++) {
cmd.Parameters.AddWithValue(paramNames[i], ids[i]);
}
}
Linq-to-SQL:
var listColumns = new List<int>() { 1, 5, 6, 9 };
db.Table.Where(x => listColumns.Distinct().Contains(x.id)).ToString();
Generated SQL:
SELECT
[Extent1].[id] AS [id],
FROM [Table] AS [Extent1]
WHERE [Extent1].[id] IN (1, 5, 6, 9)
EDIT
An approach that yields parameterized SQL (not that it's all that useful if the number of parameters keeps changing):
listColumns.Distinct().Aggregate(db.Table, (current, c) => current.Where(x => c == x.id)).ToString();
((System.Web.UI.MobileControls.List)listColumns).ListItem.Valuecan have a string value with comma separated int types? Please show how the listColumns object contains these random int's.