在2个数据表上完全外连接，并有一列列
我有2个数据表，我不知道他们的数据列的列表。 该列表必须在运行时提取，并用于完整外连接。
使用这些列时，需要合并两个表格之间的列，并且需要显示所有数据。
直到现在我正在做的是
但是，我在第二步中遇到了Linq问题。
直到现在我有：
获取常用列
// Get common columns
var commonColumns = dt1.Columns.OfType().Intersect(dt2.Columns.OfType(), new DataColumnComparer());
创建新的数据表
// Create the result which is going to be sent to the user
DataTable result = new DataTable();
// Add all the columns from both tables
result.Columns.AddRange(
dt1.Columns.OfType()
.Union(dt2.Columns.OfType(), new DataColumnComparer())
.Select(c => new DataColumn(c.Caption, c.DataType, c.Expression, c.ColumnMapping)).ToArray());
如何从运行时提取的datacolumns列表中动态获取有效的完整外连接？
这可能适合你
var commonColumns = dt1.Columns.OfType<DataColumn>().Intersect(dt2.Columns.OfType<DataColumn>(), new DataColumnComparer());
DataTable result = new DataTable();
dt1.PrimaryKey = commonColumns.ToArray();
result.Merge(dt1, false, MissingSchemaAction.AddWithKey);
result.Merge(dt2, false, MissingSchemaAction.AddWithKey);
基于Matthew的回答，我创建了一个接受2个以上数据表的函数。 我希望这有助于：
用法：
var table123 = FullOuterJoinDataTables(table1, table2, table3);
这里是功能来源：
public DataTable FullOuterJoinDataTables(params DataTable[] datatables) // supports as many datatables as you need.
{
DataTable result = datatables.First().Clone();
var commonColumns = result.Columns.OfType<DataColumn>();
foreach (var dt in datatables.Skip(1))
{
commonColumns = commonColumns.Intersect(dt.Columns.OfType<DataColumn>(), new DataColumnComparer());
}
result.PrimaryKey = commonColumns.ToArray();
foreach (var dt in datatables)
{
result.Merge(dt, false, MissingSchemaAction.AddWithKey);
}
return result;
}
/* also create this class */
public class DataColumnComparer : IEqualityComparer<DataColumn>
{
public bool Equals(DataColumn x, DataColumn y) => x.Caption == y.Caption;
public int GetHashCode(DataColumn obj) => obj.Caption.GetHashCode();
}
我也努力得到答案，我正在复制粘贴整个代码。 我相信这会帮助你。
您只需要DataTable1 ， DataTable2和这两个表的主primarykeys就可以执行此连接。 您可以将数据表主键设置为
datatable1.PrimaryKey = new DataColumn[] { captureDT.Columns["Your Key Name"] };
//你的代码
/// <summary>
/// Combines the data of two data table into a single data table. The grouping of tables
/// will be based on the primary key provided for both the tables.
/// </summary>
/// <param name="table1"></param>
/// <param name="table2"></param>
/// <param name="table1PrimaryKey"></param>
/// <param name="table2PrimaryKey"></param>
/// <returns></returns>
private DataTable DataTablesOuterJoin(DataTable table1, DataTable table2, string table1PrimaryKey, string table2PrimaryKey)
{
DataTable flatDataTable = new DataTable();
foreach (DataColumn column in table2.Columns)
{
flatDataTable.Columns.Add(new DataColumn(column.ToString()));
}
foreach (DataColumn column in table1.Columns)
{
flatDataTable.Columns.Add(new DataColumn(column.ToString()));
}
// Retrun empty table with required columns to generate empty extract
if (table1.Rows.Count <= 0 && table2.Rows.Count <= 0)
{
flatDataTable.Columns.Remove(table2PrimaryKey);
return flatDataTable;
}
var dataBaseTable2 = table2.AsEnumerable();
var groupDataT2toT1 = dataBaseTable2.GroupJoin(table1.AsEnumerable(),
br => new { id = br.Field<string>(table2PrimaryKey).Trim().ToLower() },
jr => new { id = jr.Field<string>(table1PrimaryKey).Trim().ToLower() },
(baseRow, joinRow) => joinRow.DefaultIfEmpty()
.Select(row => new
{
flatRow = baseRow.ItemArray.Concat((row == null) ? new object[table1.Columns.Count] :
row.ItemArray).ToArray()
})).SelectMany(s => s);
var dataBaseTable1 = table1.AsEnumerable();
var groupDataT1toT2 = dataBaseTable1.GroupJoin(table2.Select(),
br => new { id = br.Field<string>(table1PrimaryKey).Trim().ToLower() },
jr => new { id = jr.Field<string>(table2PrimaryKey).Trim().ToLower() },
(baseRow, joinRow) => joinRow.DefaultIfEmpty()
.Select(row => new
{
flatRow = (row == null) ? new object[table2.Columns.Count].ToArray().Concat(baseRow.ItemArray).ToArray() :
row.ItemArray.Concat(baseRow.ItemArray).ToArray()
})).SelectMany(s => s);
// Get the union of both group data to single set
groupDataT2toT1 = groupDataT2toT1.Union(groupDataT1toT2);
// Load the grouped data to newly created table
foreach (var result in groupDataT2toT1)
{
flatDataTable.LoadDataRow(result.flatRow, false);
}
// Get the distinct rows only
IEnumerable rows = flatDataTable.Select().Distinct(DataRowComparer.Default);
// Create a new distinct table with same structure as flatDataTable
DataTable distinctFlatDataTable = flatDataTable.Clone();
distinctFlatDataTable.Rows.Clear();
// Push all the rows into distinct table.
// Note: There will be two different columns for primary key1 and primary key2. In grouped rows,
// primary key1 or primary key2 can have empty values. So copy all the primary key2 values to
// primary key1 only if primary key1 value is empty and then delete the primary key2. So at last
// we will get only one perimary key. Please make sure the non-deleted key must be present in
foreach (DataRow row in rows)
{
if (string.IsNullOrEmpty(row[table1PrimaryKey].ToString()))
row[table1PrimaryKey] = row[table2PrimaryKey];
if (string.IsNullOrEmpty(row[CaptureBusDateColumn].ToString()))
row[CaptureBusDateColumn] = _businessDate;
if (string.IsNullOrEmpty(row[CaptureUserIDColumn].ToString()))
row[CaptureUserIDColumn] = row[StatsUserIDColumn];
distinctFlatDataTable.ImportRow(row);
}
// Sort the table based on primary key.
DataTable sortedFinaltable = (from orderRow in distinctFlatDataTable.AsEnumerable()
orderby orderRow.Field<string>(table1PrimaryKey)
select orderRow).CopyToDataTable();
// Remove primary key2 as we have already copied it to primary key1
sortedFinaltable.Columns.Remove(table2PrimaryKey);
return ReplaceNulls(sortedFinaltable, "0");
}
/// <summary>
/// Replace all the null values from data table with specified string
/// </summary>
/// <param name="dt"></param>
/// <param name="replaceStr"></param>
/// <returns></returns>
private DataTable ReplaceNulls(DataTable dt, string replaceStr)
{
for (int a = 0; a < dt.Rows.Count; a++)
{
for (int i = 0; i < dt.Columns.Count; i++)
{
if (dt.Rows[a][i] == DBNull.Value)
{
dt.Rows[a][i] = replaceStr;
}
}
}
return dt;
}
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