你能帮我用SQL语句来查找多个字段的重复项吗？
例如,在伪代码中:
select count(field1,field2,field3)
from table
where the combination of field1, field2, field3 occurs multiple times
并且从上面的陈述中,如果有多次出现,我想选择除第一个以外的每个记录.
我需要重新启动数据库,因为某些进程无法正常工作.我的计划是让它脱机并重新上线.
我试图在Sql Server Management Studio 2008中执行此操作:
use master;
go
alter database qcvalues
set single_user
with rollback immediate;
alter database qcvalues
set multi_user;
go
我收到这些错误:
Msg 5061, Level 16, State 1, Line 1
ALTER DATABASE failed because a lock could not be placed on database 'qcvalues'. Try again later.
Msg 5069, Level 16, State 1, Line 1
ALTER DATABASE statement failed.
Msg 5061, Level 16, State 1, Line 4
ALTER DATABASE failed because a lock could not be placed on database …我循环遍历数据表中的每一行:
foreach (DataRow row in dt.Rows) {}
我想得到dt datatable中当前行的索引.例如:
int index = dt.Rows[current row number]
我该怎么做呢？
我在这做错了什么？我收到此错误:
SELECT LEFT(SUBSTRING(batchinfo.datapath, PATINDEX('%[0-9][0-9][0-9]%', batchinfo.datapath), 8000),
PATINDEX('%[^0-9]%', SUBSTRING(batchinfo.datapath, PATINDEX('%[0-9][0-9][0-9]%',
batchinfo.datapath), 8000))-1),
qvalues.name,
qvalues.compound,
qvalues.rid
FROM batchinfo JOIN qvalues ON batchinfo.rowid=qvalues.rowid
WHERE LEN(datapath)>4
GROUP BY 1,2,3
HAVING rid!=MAX(rid)
我想按第一列,第二列和第三列进行分组.
没有团体和没有,它工作正常.
var lines = File.ReadAllLines(filelocation);
char[] space = { ',' };
string templine;
foreach (string line in lines)
{}
我该怎么办foreach (string line in lines[1:])？我想跳过第一个元素并从第二个元素开始foreach
可能重复:
Foreach循环,确定哪个是循环的最后一次迭代
foreach (DataRowView row in orderedTable.DefaultView)
{
if(lasttime) do-something;
}
orderedtable是一个数据表
有谁知道如何找出我们是否在最后的foreach迭代？请记住,我确实在ordertable中有重复
我有以下代码片段,产生编译错误:
public List<string> batchaddresses;
public MapFiles(string [] addresses)
{
for (int i = 0; i < addresses.Count(); i++)
{
batchaddresses.AddRange(Directory.GetFiles(addresses[i], "*.esy"));
}
}
我尝试使用该List<T>.AddRange()方法时出错:
Object reference not set to an instance of an object
我究竟做错了什么？
我试图通过使用HtmlAgilityPack解析html从html表中获取信息.
这是HTML的样子:
...
...
...
<tbody>
<tr>
<td class="style_19" style="vertical-align: baseline;">
<div class="style_18">AA00857</div>
</td>
<td class="style_19" style="vertical-align: baseline;">
<div></div>
<div class="style_20">TPRCF</div>
</td>
<td class="style_19" style="vertical-align: baseline;">
<div class="style_21"></div>
</td>
<td class="style_19" style="vertical-align: baseline;">
<div class="style_21">16908/2</div>
</td>
<td class="style_19" style="vertical-align: baseline;">
<div class="style_18"> ETG_C</div>
</td>
</tr>
<tr>
<td class="style_19" style="vertical-align: baseline;">
<div class="style_18">AA01231</div>
</td>
<td class="style_19" style="vertical-align: baseline;">
<div></div>
<div class="style_20">TPRCF</div>
</td>
<td class="style_19" style="vertical-align: baseline;">
<div class="style_21"></div>
</td>
<td class="style_19" style="vertical-align: baseline;">
<div class="style_21">16909/19</div>
</td>
<td class="style_19" style="vertical-align: baseline;">
<div class="style_18"> ETG_C</div> …我有一个字符串列表:
\\\\Tecan1\\tecan #1 output\\15939-E.ESY\r\n
\\\\Tecan1\\tecan #1 output\\15942-E.ESY\r\n
\\\\Tecan1\\tecan #1 output\\15945-E.ESY\r\n
\\\\Tecan1\\tecan #1 output\\15948-E.ESY\r\n
\\\\Tecan1\\tecan #1 output\\15951-E.ESY\r\n
\\\\Tecan1\\tecan #1 output\\15954-E.ESY\r\n
\\\\Tecan1\\tecan #1 output\\15957-E.ESY\r\n
\\\\Tecan1\\tecan #1 output\\15960-E.ESY\r\n
\\\\Tecan1\\tecan #1 output\\15963-E.ESY\r\n
\\\\Tecan_2\\output on tecan 2\\15940-E.ESY\r\n
\\\\Tecan_2\\output on tecan 2\\15943-E.ESY\r\n
\\\\Tecan_2\\output on tecan 2\\15946-E.ESY\r\n
\\\\Tecan_2\\output on tecan 2\\15949-E.ESY\r\n
\\\\Tecan_2\\output on tecan 2\\15952-E.ESY\r\n
\\\\Tecan_2\\output on tecan 2\\15955-E.ESY\r\n
\\\\Tecan_2\\output on tecan 2\\15958-E.ESY\r\n
\\\\Tecan_2\\output on tecan 2\\15961-E.ESY\r\n
\\\\Tecan-5\\Output\\15941-E.ESY\r\n
\\\\Tecan-5\\Output\\15944-E.ESY\r\n
\\\\Tecan-5\\Output\\15947-E.ESY\r\n
\\\\Tecan-5\\Output\\15950-E.ESY\r\n
\\\\Tecan-5\\Output\\15953-E.ESY\r\n
\\\\Tecan-5\\Output\\15956-E.ESY\r\n
\\\\Tecan-5\\Output\\15959-E.ESY\r\n
\\\\Tecan-5\\Output\\15962-E.ESY\r\n
每个\ r \n应该是一个新行.抱歉格式不好
我需要按文件名15939-E.ESY等对列表进行排序...我需要按文件名的字母数字顺序排列整个列表.我怎么这样排序呢？