select * from feelist where feebuyerSp in("+feebuySp+") and feebuyerSp is not null

------解决方案--------------------
string sql = "";
if(feebuySp == "")
{
  sql = select * from feelist }
else
{
  sql = select * from feelist where feebuyerSp in("+feebuySp+")
}


------解决方案--------------------
SQL code
select * from feelist where feebuyerSp is null or feebuyerSp ='' or feebuyerSp  like '%'+feebuySp+'%')

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SQL code
if isnull(feebuySp,'')=''
select * from feelist

------解决方案--------------------
SQL code

select * from feelist where feebuyerSp in("+feebuySp+") or feebuyerSp !=""

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SQL code


string sql = "select * from feelist";
if(feebuyerbhFX.Text.Trim().Length)
{
  string feebuySp="'"+feebuyerbhFX.Text.Replace(",","','")+"'"; 
  sql += " where feebuyerSp in("+feebuySp+")";
}

------解决方案--------------------
如果feebuySp<>null then  
select * from feelist where feebuyerSp in("+feebuySp+")
否则 select * from feelist

------解决方案--------------------
引用楼主 liuvb 的帖子:

如果feebuySp不为空时，这样没问题，如果feebuySp为空时，我想得到全部记录，应该怎么改一下？ 
string feebuySp="'"+feebuyerbhFX.Text.Replace(",","','")+"'"; 

select * from feelist where feebuyerSp in("+feebuySp+")


------解决方案--------------------
C# code
 string feebuySp = "'" + feebuyerbhFX.Text.Replace(",", "','") + "'";
        string sql = "select * from feelist where feebuyerSp in ('"+feebuySp+"')";

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SQL code
select * from feelist where feebuyerSp is null

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在程序中加个判断，分别用不同的SQL
if(feebuySp==null)
{
  select * from feelist
}
else
{
  select * from feelist where feebuyerSp in("+feebuySp+")
}

------解决方案--------------------
引用楼主 liuvb 的帖子:

如果feebuySp不为空时，这样没问题，如果feebuySp为空时，我想得到全部记录，应该怎么改一下？ 
string feebuySp="'"+feebuyerbhFX.Text.Replace(",","','")+"'"; 

select * from feelist where feebuyerSp in("+feebuySp+")


------解决方案--------------------
探讨

引用楼主 liuvb 的帖子:
SQL codeselect * from feelist where feebuyerSp is null or feebuyerSp in("+feebuySp+")


------解决方案--------------------