var inClause = "(" + String.Join(",", values.Select(x => x.ToString()).ToArray()) + ")"; 

注意 ：您不再需要在.NET Framework 4中调用.ToArray() 。添加了一个新的String.Join(string separator, IEnumerable values)方法。

您可以使用String.Join方法，如下所示：

 var str = "(" + string.Join(", ", Array.ConvertAll(values, v => v.ToString(CultureInfo.InvariantCulture))); 

假设values是一个数组， Array.ConvertAll应该比带有ToArray LINQ更有效。

如果您无权访问.NET 3.5扩展方法，则可以执行以下操作：

 StringBuilder sb = new StringBuilder(); sb.Append('('); foreach (int i in values) { sb.Append(i).Append(','); } // remove final , sb.Length -= 1; sb.Append(')'); string inValue = sb.ToString(); 

哪个适用于.NET 2

这也可以在一行中完成

 public string ToInStatement(this int[] values) { string[] stringValues = Array.ConvertAll(values, Convert.ToString); string result = "(" + String.Join(",", stringValues) + ")"; return result; } 

如果整数列表很大，则可能最终生成的字符串太长，数据库无法接受。 例如，我认为SQL2000中VARCHAR的最大长度约为8K。

所以我有一组辅助方法，如下面的示例，它返回一个字符串的枚举，然后可以按如下方式使用：

 List idList = ...; using(SqlCommand command = ...) { ... foreach(string idString in ConcatenateValues(ids,",", maxLength, false)) { command.Parameters[...] = idString; // or command.CommandText = "SELECT ... IN (" + idString + ")..."; ... execute command ... } } 

连接方法可能如下所示：

 public static IEnumerable ConcatenateValues(IEnumerable values, string separator, int maxLength, bool skipDuplicates) { IDictionary valueDictionary = null; StringBuilder sb = new StringBuilder(); if (skipDuplicates) { valueDictionary = new Dictionary(); } foreach (int value in values) { if (skipDuplicates) { if (valueDictionary.ContainsKey(value)) continue; valueDictionary.Add(value, ""); } string s = value.ToString(CultureInfo.InvariantCulture); if ((sb.Length + separator.Length + s.Length) > maxLength) { // Max length reached, yield the result and start again if (sb.Length > 0) yield return sb.ToString(); sb.Length = 0; } if (sb.Length > 0) sb.Append(separator); sb.Append(s); } // Yield whatever's left over if (sb.Length > 0) yield return sb.ToString(); } 

您可以使用以下扩展方法更有效地执行此操作：

  ///
Appends a list of strings to a StringBuilder, separated by a separator string.
 ///The StringBuilder to append to. ///The strings to append. ///A string to append between the strings. public static StringBuilder AppendJoin(this StringBuilder builder, IEnumerable strings, string separator) { if (builder == null) throw new ArgumentNullException("builder"); if (strings == null) throw new ArgumentNullException("strings"); if (separator == null) throw new ArgumentNullException("separator"); bool first = true; foreach (var str in strings) { if (first) first = false; else builder.Append(separator); builder.Append(str); } return builder; } ///
Combines a collection of strings into a single string.
 public static string Join(this IEnumerable strings, string separator, Func selector) { return strings.Select(selector).Join(separator); } ///
Combines a collection of strings into a single string.
 public static string Join(this IEnumerable strings, string separator) { return new StringBuilder().AppendJoin(strings, separator).ToString(); } 

嘿，很棒的建议，下面稍作修改

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 public static class IEnumerableExtensions { // reasonable to assume you will use this everywhere, not just // Sql statements, but log statements, anywhere you need to // dump a list into a readable format! // // HINT: extra credit: you can generalize this, and provide // specialized short hands that invoke the general method public static string ToCommaSeparatedString(this IEnumerable values) { // SIGH: so apparently this does not generate minimal // assembler on every machine, please note the following // is written for clarity, please feel free to substitute // your own favourite ultra-performance high-octance // string appender algorithm StringBuilder commaSeparated = new StringBuilder (); foreach (T value in values) { // PERF: store format string as const commaSeparated.AppendFormat ("{0}, ", value); } // PERF: store trim chars as static readonly array return commaSeparated.Trim (", ".ToCharArray ()); } } ... // elsewhere in code List myIdentifiers = new List { 1, 2, 3, 4, 5, }; string mySqlIdentifierList = myIdentifiers.ToCommaSeparatedList (); string mySqlStatementFormat = "SELECT * FROM [SomeTable] WHERE [Id] IN ({0})"; string mySqlStatement = string.format (mySqlStatementFormat, mySqlIdentifierList); ... 

 /// 
 /// Converts an array of integers into a string that may be used in a SQL IN expression. /// 
 /// The array to convert. /// A string representing the array as a parenthetical comma-delemited list. If the array /// is empty or missing, then "(null)" is returned. public static string ToSqlInList(int[] values) { if (values == null || values.Length == 0) return "(null)"; // In SQL the expression "IN (NULL)" is always false. return string.Concat("(", string.Join(",", Array.ConvertAll(values,x=>x.ToString())), ")"); }