我在这里越来越绝望。我无法弄清楚为什么会发生此异常。我搜索并阅读了这个问题，似乎每个人都设法用 command.Parameters.Clear() 解决了这个问题，但这对我不起作用。这是我的代码：
public class ProductsDataAccess : Connection
{
public static SqlParameter[] createParams(Products prod)
{
SqlParameter idParam = new SqlParameter("@id", prod.prodID);
idParam.SqlDbType = System.Data.SqlDbType.VarChar;
idParam.Size = 45;
idParam.IsNullable = false;
idParam.Direction = ParameterDirection.Input;
SqlParameter nameParam = new SqlParameter("@name", prod.prodName);
nameParam.SqlDbType = System.Data.SqlDbType.VarChar;
nameParam.Size = 45;
nameParam.IsNullable = false;
nameParam.Direction = ParameterDirection.Input;
SqlParameter demandParam = new SqlParameter("@demand", prod.demand);
demandParam.SqlDbType = System.Data.SqlDbType.Int;
demandParam.IsNullable = false;
demandParam.Direction = ParameterDirection.Input;
SqlParameter demandLTParam = new SqlParameter("@demandLT", prod.demandLT);
demandLTParam.SqlDbType = System.Data.SqlDbType.Int;
demandLTParam.IsNullable = false;
demandLTParam.Direction = ParameterDirection.Input;
SqlParameter leadTimeParam = new SqlParameter("@leadTime", prod.leadTime);
leadTimeParam.SqlDbType = System.Data.SqlDbType.Int;
leadTimeParam.IsNullable = false;
leadTimeParam.Direction = ParameterDirection.Input;
SqlParameter fixedCoastParam = new SqlParameter("@k", prod.k);
fixedCoastParam.SqlDbType = System.Data.SqlDbType.Float;
fixedCoastParam.IsNullable = false;
fixedCoastParam.Direction = ParameterDirection.Input;
SqlParameter cParam = new SqlParameter("@c", prod.c);
cParam.SqlDbType = System.Data.SqlDbType.Float;
cParam.IsNullable = false;
cParam.Direction = ParameterDirection.Input;
SqlParameter chPrecentageParam = new SqlParameter("@chPrecent", prod.precentOfC);
chPrecentageParam.SqlDbType = System.Data.SqlDbType.Int;
chPrecentageParam.IsNullable = false;
chPrecentageParam.Direction = ParameterDirection.Input;
SqlParameter chParam = new SqlParameter("@ch", prod.ch);
chParam.SqlDbType = System.Data.SqlDbType.Float;
chParam.IsNullable = false;
chParam.Direction = ParameterDirection.Input;
SqlParameter optimalQParam = new SqlParameter("@q", prod.q);
optimalQParam.SqlDbType = System.Data.SqlDbType.Int;
optimalQParam.IsNullable = false;
optimalQParam.Direction = ParameterDirection.Input;
SqlParameter annualChParam = new SqlParameter("@annualCh", prod.annualCh);
annualChParam.SqlDbType = System.Data.SqlDbType.Float;
annualChParam.IsNullable = false;
annualChParam.Direction = ParameterDirection.Input;
SqlParameter annualKParam = new SqlParameter("@annualK", prod.annualK);
annualKParam.SqlDbType = System.Data.SqlDbType.Float;
annualKParam.IsNullable = false;
annualKParam.Direction = ParameterDirection.Input;
SqlParameter optimalTACParam = new SqlParameter("@tac", prod.tac);
optimalTACParam.SqlDbType = System.Data.SqlDbType.Float;
optimalTACParam.IsNullable = false;
optimalTACParam.Direction = ParameterDirection.Input;
SqlParameter rParam = new SqlParameter("@r", prod.r);
rParam.SqlDbType = System.Data.SqlDbType.Int;
rParam.IsNullable = false;
rParam.Direction = ParameterDirection.Input;
SqlParameter inventoryLvlParam = new SqlParameter("@invLvl", prod.inventoryLvl);
inventoryLvlParam.SqlDbType = System.Data.SqlDbType.Int;
inventoryLvlParam.IsNullable = false;
inventoryLvlParam.Direction = ParameterDirection.Input;
SqlParameter statusParam = new SqlParameter("@status", prod.status);
statusParam.SqlDbType = System.Data.SqlDbType.VarChar;
statusParam.Size = 10;
statusParam.IsNullable = false;
statusParam.Direction = ParameterDirection.Input;
SqlParameter[] paramList = {idParam, nameParam, demandParam, demandLTParam,
leadTimeParam, fixedCoastParam, cParam,
chPrecentageParam, chParam, optimalQParam,
annualChParam, annualKParam, optimalTACParam,
rParam, inventoryLvlParam, statusParam };
return paramList;
}
public static void insertProduct(Products product)
{
String comStr = "insert into Products(prodID, name, demand, demandLT, leadTime, fixedCoast, " +
"c, chAsPrecentage, ch, optimalQ, annualCh, annualK, optimalTAC, r, inventoryLvl, prodStatus) " +
"values(@id, @name, @demand, @demandLT, @leadTime, @k, @c, @chPrecent, " +
"@ch, @q, @annualCh, @annualK, @tac, @r, @invLvl, @status)";
createConncetion();
SqlCommand command = new SqlCommand(comStr, con);
command.Parameters.AddRange(createParams(product));
openConnection();
command.ExecuteNonQuery();
closeConnection();
command.Parameters.Clear()
command.Dispose();
}
public static DataTable getAllProducts()
{
String comStr = "select prodID, name, demand, demandLT, leadTime, fixedCoast, c, chAsPrecentage, " +
"ch, optimalQ, annualCh, annualK, optimalTAC, r, inventoryLvl, prodStatus from Products";
createConncetion();
SqlCommand command = new SqlCommand(comStr, con);
DataTable table = new DataTable("allProduct");
SqlDataAdapter adapter = new SqlDataAdapter();
adapter.SelectCommand=command;
openConnection();
adapter.Fill(table);
command.Dispose();
closeConnection();
return table;
}
}
这是我使用 sqlParameters 的另一个类：
public class StatisticsDataAccess : Connection
{
public static SqlParameter[] createParams(Statistics stat, string prodID)
{
SqlParameter idParam = new SqlParameter("@id", prodID);
idParam.SqlDbType = System.Data.SqlDbType.VarChar;
idParam.Size = 45;
idParam.IsNullable = false;
idParam.Direction = ParameterDirection.Input;
SqlParameter m1Param = new SqlParameter("@m1", stat.month1);
m1Param.SqlDbType = System.Data.SqlDbType.Int;
m1Param.IsNullable = false;
m1Param.Direction = ParameterDirection.Input;
SqlParameter m2Param = new SqlParameter("@m2", stat.month2);
m2Param.SqlDbType = System.Data.SqlDbType.Int;
m2Param.IsNullable = false;
m2Param.Direction = ParameterDirection.Input;
SqlParameter m3Param = new SqlParameter("@m3", stat.month3);
m3Param.SqlDbType = System.Data.SqlDbType.Int;
m3Param.IsNullable = false;
m3Param.Direction = ParameterDirection.Input;
SqlParameter m4Param = new SqlParameter("@m4", stat.month4);
m4Param.SqlDbType = System.Data.SqlDbType.Int;
m4Param.IsNullable = false;
m4Param.Direction = ParameterDirection.Input;
SqlParameter m5Param = new SqlParameter("@m5", stat.month5);
m5Param.SqlDbType = System.Data.SqlDbType.Int;
m5Param.IsNullable = false;
m5Param.Direction = ParameterDirection.Input;
SqlParameter m6Param = new SqlParameter("@m6", stat.month6);
m6Param.SqlDbType = System.Data.SqlDbType.Int;
m6Param.IsNullable = false;
m6Param.Direction = ParameterDirection.Input;
SqlParameter m7Param = new SqlParameter("@m7", stat.month7);
m7Param.SqlDbType = System.Data.SqlDbType.Int;
m7Param.IsNullable = false;
m7Param.Direction = ParameterDirection.Input;
SqlParameter m8Param = new SqlParameter("@m8", stat.month8);
m8Param.SqlDbType = System.Data.SqlDbType.Int;
m8Param.IsNullable = false;
m8Param.Direction = ParameterDirection.Input;
SqlParameter m9Param = new SqlParameter("@m9", stat.month9);
m9Param.SqlDbType = System.Data.SqlDbType.Int;
m9Param.IsNullable = false;
m9Param.Direction = ParameterDirection.Input;
SqlParameter m10Param = new SqlParameter("@m10", stat.month10);
m10Param.SqlDbType = System.Data.SqlDbType.Int;
m10Param.IsNullable = false;
m10Param.Direction = ParameterDirection.Input;
SqlParameter m11Param = new SqlParameter("@m11", stat.month11);
m11Param.SqlDbType = System.Data.SqlDbType.Int;
m11Param.IsNullable = false;
m11Param.Direction = ParameterDirection.Input;
SqlParameter m12Param = new SqlParameter("@m12", stat.month12);
m12Param.SqlDbType = System.Data.SqlDbType.Int;
m12Param.IsNullable = false;
m12Param.Direction = ParameterDirection.Input;
SqlParameter[] paramList = {idParam, m1Param, m2Param, m3Param, m4Param,
m5Param, m6Param, m7Param, m8Param, m8Param,
m10Param, m11Param, m12Param };
return paramList;
}
public static void insertStatistic(Statistics stat, string prodID)
{
String comStr = "insert into LTDStatistic(prodID, month1, month2, month3, month4, month5, " +
"month6, month7, month8, month9, month10, month11, month12)" +
"values(@id, @m1, @m2, @m3, @m4, @m5, @m6, @m7, @m8, @m9, @m10, @m11, @m12)";
createConncetion();
SqlCommand command = new SqlCommand(comStr, con);
command.Parameters.AddRange(createParams(stat, prodID));
openConnection();
command.ExecuteNonQuery();
closeConnection();
command.Parameters.Clear();
command.Dispose();
}
}
WCF 服务使用这些类中的方法来修改数据库
public void create(ProductsData product)
{
Statistics statDLT = new Statistics(product.demandLTStat.month1, product.demandLTStat.month2,
product.demandLTStat.month3, product.demandLTStat.month4, product.demandLTStat.month5,
product.demandLTStat.month6, product.demandLTStat.month7, product.demandLTStat.month8,
product.demandLTStat.month9, product.demandLTStat.month10, product.demandLTStat.month11,
product.demandLTStat.month12);
Products newProd = new Products(product.prodID, product.prodName,
product.leadTime, product.k, product.c, product.precentOfC,
product.demand, statDLT);
newProd.callculate();
newProd.determineR();
ProductsDataAccess.insertProduct(newProd);
//String plsWork = newProd.prodID;
StatisticsDataAccess.insertStatistic(newProd.demandLTStat, newProd.prodID);
}
也许我错过了事情如何运作的一些重要方面......我不知道。希望有人可以帮助我，并对长代码段感到抱歉。