我试图将数组参数传递给C#中的SQL commnd,如下所示,但它不起作用.有没有人见过它？
string sqlCommand = "SELECT * from TableA WHERE Age IN (@Age)";
SqlConnection sqlCon = new SqlConnection(connectString);
SqlCommand sqlComm = new SqlCommand();
sqlComm.Connection = sqlCon;
sqlComm.CommandType = System.Data.CommandType.Text;
sqlComm.CommandText = sqlCommand;
sqlComm.CommandTimeout = 300;
sqlComm.Parameters.Add("@Age", SqlDbType.NVarChar);
StringBuilder sb = new StringBuilder();
foreach (ListItem item in ddlAge.Items)
{
if (item.Selected)
{
sb.Append(item.Text + ",");
}
}
sqlComm.Parameters["@Age"].Value = sb.ToString().TrimEnd(',');
Bri*_*ian 149
您需要一次添加一个数组中的值.
var parameters = new string[items.Length];
var cmd = new SqlCommand();
for (int i = 0; i < items.Length; i++)
{
parameters[i] = string.Format("@Age{0}", i);
cmd.Parameters.AddWithValue(parameters[i], items[i]);
}
cmd.CommandText = string.Format("SELECT * from TableA WHERE Age IN ({0})", string.Join(", ", parameters));
cmd.Connection = new SqlConnection(connStr);
更新:这是一个扩展和可重用的解决方案,使用Adam的答案以及他建议的编辑.我对它进行了一些改进,并使其成为一种扩展方法,使其更容易调用.
public static class SqlCommandExt
{
/// <summary>
/// This will add an array of parameters to a SqlCommand. This is used for an IN statement.
/// Use the returned value for the IN part of your SQL call. (i.e. SELECT * FROM table WHERE field IN ({paramNameRoot}))
/// </summary>
/// <param name="cmd">The SqlCommand object to add parameters to.</param>
/// <param name="paramNameRoot">What the parameter should be named followed by a unique value for each value. This value surrounded by {} in the CommandText will be replaced.</param>
/// <param name="values">The array of strings that need to be added as parameters.</param>
/// <param name="dbType">One of the System.Data.SqlDbType values. If null, determines type based on T.</param>
/// <param name="size">The maximum size, in bytes, of the data within the column. The default value is inferred from the parameter value.</param>
public static SqlParameter[] AddArrayParameters<T>(this SqlCommand cmd, string paramNameRoot, IEnumerable<T> values, SqlDbType? dbType = null, int? size = null)
{
/* An array cannot be simply added as a parameter to a SqlCommand so we need to loop through things and add it manually.
* Each item in the array will end up being it's own SqlParameter so the return value for this must be used as part of the
* IN statement in the CommandText.
*/
var parameters = new List<SqlParameter>();
var parameterNames = new List<string>();
var paramNbr = 1;
foreach (var value in values)
{
var paramName = string.Format("@{0}{1}", paramNameRoot, paramNbr++);
parameterNames.Add(paramName);
SqlParameter p = new SqlParameter(paramName, value);
if (dbType.HasValue)
p.SqlDbType = dbType.Value;
if (size.HasValue)
p.Size = size.Value;
cmd.Parameters.Add(p);
parameters.Add(p);
}
cmd.CommandText = cmd.CommandText.Replace("{" + paramNameRoot + "}", string.Join(",", parameterNames));
return parameters.ToArray();
}
}
这被称为......
var cmd = new SqlCommand("SELECT * FROM TableA WHERE Age IN ({Age})");
cmd.AddArrayParameters("Age", new int[] { 1, 2, 3 });
请注意,sql语句中的"{Age}"与我们发送给AddArrayParameters的参数名称相同.AddArrayParameters将使用正确的参数替换该值.
J A*_*ers 38
我想扩展Brian为使其在其他地方轻松使用而做出的贡献.
/// <summary>
/// This will add an array of parameters to a SqlCommand. This is used for an IN statement.
/// Use the returned value for the IN part of your SQL call. (i.e. SELECT * FROM table WHERE field IN (returnValue))
/// </summary>
/// <param name="sqlCommand">The SqlCommand object to add parameters to.</param>
/// <param name="array">The array of strings that need to be added as parameters.</param>
/// <param name="paramName">What the parameter should be named.</param>
protected string AddArrayParameters(SqlCommand sqlCommand, string[] array, string paramName)
{
/* An array cannot be simply added as a parameter to a SqlCommand so we need to loop through things and add it manually.
* Each item in the array will end up being it's own SqlParameter so the return value for this must be used as part of the
* IN statement in the CommandText.
*/
var parameters = new string[array.Length];
for (int i = 0; i < array.Length; i++)
{
parameters[i] = string.Format("@{0}{1}", paramName, i);
sqlCommand.Parameters.AddWithValue(parameters[i], array[i]);
}
return string.Join(", ", parameters);
}
您可以使用以下新功能:
SqlCommand cmd = new SqlCommand();
string ageParameters = AddArrayParameters(cmd, agesArray, "Age");
sql = string.Format("SELECT * FROM TableA WHERE Age IN ({0})", ageParameters);
cmd.CommandText = sql;
public static class Extensions
{
public static void AddArrayParameters<T>(this SqlCommand cmd, string name, IEnumerable<T> values)
{
name = name.StartsWith("@") ? name : "@" + name;
var names = string.Join(", ", values.Select((value, i) => {
var paramName = name + i;
cmd.Parameters.AddWithValue(paramName, value);
return paramName;
}));
cmd.CommandText = cmd.CommandText.Replace(name, names);
}
}
然后,您可以使用此扩展方法,如下所示:
var ageList = new List<int> { 1, 3, 5, 7, 9, 11 };
var cmd = new SqlCommand();
cmd.CommandText = "SELECT * FROM MyTable WHERE Age IN (@Age)";
cmd.AddArrayParameters("Age", ageList);
确保在调用AddArrayParameters之前设置CommandText.
还要确保您的参数名称不会与语句中的任何其他名称部分匹配(即@AgeOfChild)
Mar*_*ell 24
如果你可以使用像"小巧玲珑"这样的工具,这可以简单地说:
int[] ages = { 20, 21, 22 }; // could be any common list-like type
var rows = connection.Query<YourType>("SELECT * from TableA WHERE Age IN @ages",
new { ages }).ToList();
Dapper会为您解决这个问题.
Gre*_*vec 12
如果您使用的是MS SQL Server 2008及更高版本,则可以使用此处描述的表值参数 http://www.sommarskog.se/arrays-in-sql-2008.html.
以下命令为整数创建表类型:
create type int32_id_list as table (id int not null primary key)
public static SqlCommand AddParameter<T>(this SqlCommand command, string name, IEnumerable<T> ids)
{
var parameter = command.CreateParameter();
parameter.ParameterName = name;
parameter.TypeName = typeof(T).Name.ToLowerInvariant() + "_id_list";
parameter.SqlDbType = SqlDbType.Structured;
parameter.Direction = ParameterDirection.Input;
parameter.Value = CreateIdList(ids);
command.Parameters.Add(parameter);
return command;
}
private static DataTable CreateIdList<T>(IEnumerable<T> ids)
{
var table = new DataTable();
table.Columns.Add("id", typeof (T));
foreach (var id in ids)
{
table.Rows.Add(id);
}
return table;
}
cmd.CommandText = "select * from TableA where Age in (select id from @age)";
cmd.AddParameter("@age", new [] {1,2,3,4,5});
既然有方法就可以了
SqlCommand.Parameters.AddWithValue(parameterName, value)
创建一个接受要替换的参数(名称)和值列表的方法可能更方便.它不是在参数级别(如AddWithValue)而是在命令本身上,所以最好将其称为AddParametersWithValues而不仅仅是AddWithValues:
查询:
SELECT * from TableA WHERE Age IN (@age)
用法:
sqlCommand.AddParametersWithValues("@age", 1, 2, 3);
扩展方法:
public static class SqlCommandExtensions
{
public static void AddParametersWithValues<T>(this SqlCommand cmd, string parameterName, params T[] values)
{
var parameterNames = new List<string>();
for(int i = 0; i < values.Count(); i++)
{
var paramName = @"@param" + i;
cmd.Parameters.AddWithValue(paramName, values.ElementAt(i));
parameterNames.Add(paramName);
}
cmd.CommandText = cmd.CommandText.Replace(parameterName, string.Join(",", parameterNames));
}
}
将项目数组作为折叠参数传递给 WHERE..IN 子句将失败，因为查询将采用WHERE Age IN ("11, 13, 14, 16").
但是您可以将参数作为序列化为 XML 或 JSON 的数组传递：
nodes()方法：StringBuilder sb = new StringBuilder();
foreach (ListItem item in ddlAge.Items)
if (item.Selected)
sb.Append("<age>" + item.Text + "</age>"); // actually it's xml-ish
sqlComm.CommandText = @"SELECT * from TableA WHERE Age IN (
SELECT Tab.col.value('.', 'int') as Age from @Ages.nodes('/age') as Tab(col))";
sqlComm.Parameters.Add("@Ages", SqlDbType.NVarChar);
sqlComm.Parameters["@Ages"].Value = sb.ToString();
OPENXML方法：using System.Xml.Linq;
...
XElement xml = new XElement("Ages");
foreach (ListItem item in ddlAge.Items)
if (item.Selected)
xml.Add(new XElement("age", item.Text);
sqlComm.CommandText = @"DECLARE @idoc int;
EXEC sp_xml_preparedocument @idoc OUTPUT, @Ages;
SELECT * from TableA WHERE Age IN (
SELECT Age from OPENXML(@idoc, '/Ages/age') with (Age int 'text()')
EXEC sp_xml_removedocument @idoc";
sqlComm.Parameters.Add("@Ages", SqlDbType.Xml);
sqlComm.Parameters["@Ages"].Value = xml.ToString();
SQL 方面的内容较多，您需要一个适当的 XML（带有根）。
OPENJSON方法（SQL Server 2016+）：using Newtonsoft.Json;
...
List<string> ages = new List<string>();
foreach (ListItem item in ddlAge.Items)
if (item.Selected)
ages.Add(item.Text);
sqlComm.CommandText = @"SELECT * from TableA WHERE Age IN (
select value from OPENJSON(@Ages))";
sqlComm.Parameters.Add("@Ages", SqlDbType.NVarChar);
sqlComm.Parameters["@Ages"].Value = JsonConvert.SerializeObject(ages);
请注意，对于最后一种方法，您还需要具有 130+ 的兼容性级别。
我想提出另一种方法，如何解决IN运算符的限制。
例如我们有以下查询
select *
from Users U
WHERE U.ID in (@ids)
我们想传递几个 ID 来过滤用户。不幸的是，不可能以简单的方式使用 C#。但是我通过使用“string_split”函数找到了解决方法。我们需要将查询重写为以下内容。
declare @ids nvarchar(max) = '1,2,3'
SELECT *
FROM Users as U
CROSS APPLY string_split(@ids, ',') as UIDS
WHERE U.ID = UIDS.value
现在我们可以轻松地传递一个参数枚举值，以逗号分隔。