检查DataTable中是否存在字符串/记录

Question

I have a String and I need to check if any column "item_manuf_id" in DataTable dtPs.Rows equals to certain value

I can loop over all Rows and compare

String id = dtPs.Rows[number]["item_manuf_id"].ToString()
if ("some value".equals(id)) etc.

but I am wondering if there is any way to check if DataTable contains the record

Answer 1

Something like this

 string find = "item_manuf_id = 'some value'";
 DataRow[] foundRows = table.Select(find);

Answer 2

Use the Find method if item_manuf_id is a primary key:

var result = dtPs.Rows.Find("some value");

If you only want to know if the value is in there then use the Contains method.

if (dtPs.Rows.Contains("some value"))
{
  ...
}

Primary key restriction applies to Contains aswell.

Answer 3

You can loop over each row of the DataTable and check the value.

I'm a big fan of using a foreach loop when using IEnumerable s. Makes it very simple and clean to look at or process each row

DataTable dtPs = // ... initialize your DataTable
foreach (DataRow dr in dtPs.Rows)
{
    if (dr["item_manuf_id"].ToString() == "some value")
    {
        // do your deed
    }
}

Alternatively you can use a PrimaryKey for your DataTable . This helps in various ways, but you often need to define one before you can use it.

An example of using one if at http://msdn.microsoft.com/en-us/library/z24kefs8(v=vs.80).aspx

DataTable workTable = new DataTable("Customers");

// set constraints on the primary key
DataColumn workCol = workTable.Columns.Add("CustID", typeof(Int32));
workCol.AllowDBNull = false;
workCol.Unique = true;

workTable.Columns.Add("CustLName", typeof(String));
workTable.Columns.Add("CustFName", typeof(String));
workTable.Columns.Add("Purchases", typeof(Double));

// set primary key
workTable.PrimaryKey = new DataColumn[] { workTable.Columns["CustID"] };

Once you have a primary key defined and data populated, you can use the Find(...) method to get the rows that match your primary key.

Take a look at http://msdn.microsoft.com/en-us/library/y06xa2h1(v=vs.80).aspx

DataRow drFound = dtPs.Rows.Find("some value");
if (drFound["item_manuf_id"].ToString() == "some value")
{
    // do your deed
}

Finally, you can use the Select() method to find data within a DataTable also found at at http://msdn.microsoft.com/en-us/library/y06xa2h1(v=vs.80).aspx .

String sExpression = "item_manuf_id == 'some value'";
DataRow[] drFound;
drFound = dtPs.Select(sExpression);

foreach (DataRow dr in drFound)
{
    // do you deed. Each record here was already found to match your criteria
}

Answer 4

I think that if your "item_manuf_id" is the primary key of the DataTable you could use the Find method ...

string s = "stringValue";
DataRow foundRow = dtPs.Rows.Find(s);
if(foundRow != null) {
 //You have it ...
 }