C# 完全外部联接,在2个数据表上,具有列列表
我有两个数据表,我不知道它们的数据列列表。此列表必须在运行时提取,并用于完全外部联接 当使用这些列时,两个表之间的列需要合并,我需要显示所有数据 到目前为止,我所做的是C# 完全外部联接,在2个数据表上,具有列列表,c#,.net,linq,ado.net,C#,.net,Linq,Ado.net,我有两个数据表,我不知道它们的数据列列表。此列表必须在运行时提取,并用于完全外部联接 当使用这些列时,两个表之间的列需要合并,我需要显示所有数据 到目前为止,我所做的是 使用intersect获取公共列,并实现IEqualityComparer 使用这些列创建一个新的datatable,以便将这两个datatable合并到此新表中 然而,在第二步中,我与Linq有问题 到目前为止,我有: 获取公共列 // Get common columns var commonColumns = dt
如何从运行时提取的数据列列表中动态获得有效的完整外部联接?我也在努力获得答案,我正在复制粘贴整个代码。我相信这会对你有所帮助 您只需要执行此联接的两个表的
DataTable1
、DataTable2
和primarykeys
。您可以将datatable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;
}
//
///将两个数据表的数据合并为一个数据表。表的分组
///将基于为两个表提供的主键。
///
///
///
///
///
///
专用DataTable DataTableOuterJoin(DataTable1、DataTable2、string table1 PrimaryKey、string table2 PrimaryKey)
{
DataTable flatDataTable=新DataTable();
foreach(表2中的DataColumn列。列)
{
flatDataTable.Columns.Add(新数据列(column.ToString());
}
foreach(表1.Columns中的DataColumn列)
{
flatDataTable.Columns.Add(新数据列(column.ToString());
}
//使用所需列重新运行空表以生成空提取
如果(table1.Rows.Count new{id=jr.Field(table1PrimaryKey).Trim().ToLower()},
(baseRow,joinRow)=>joinRow.DefaultIfEmpty()
.选择(行=>新建)
{
flatRow=baseRow.ItemArray.Concat((row==null)?新对象[table1.Columns.Count]:
row.ItemArray.ToArray()
}))。选择多个(s=>s);
var dataBaseTable1=table1.basenumerable();
var groupDataT1toT2=dataBaseTable1.GroupJoin(table2.Select(),
br=>新建{id=br.Field(table1PrimaryKey).Trim().ToLower()},
jr=>新的{id=jr.Field(table2PrimaryKey).Trim().ToLower()},
(baseRow,joinRow)=>joinRow.DefaultIfEmpty()
.选择(行=>新建)
{
flatRow=(row==null)?新对象[table2.Columns.Count].ToArray().Concat(baseRow.ItemArray).ToArray():
row.ItemArray.Concat(baseRow.ItemArray.ToArray())
}))。选择多个(s=>s);
//将两个组数据的并集获取到单个集合
groupDataT2toT1=groupDataT2toT1.Union(groupDataT1toT2);
//将分组数据加载到新创建的表中
foreach(groupDataT2toT1中的var结果)
{
flatDataTable.LoadDataRow(result.flatRow,false);
}
//仅获取不同的行
IEnumerable rows=flatDataTable.Select().Distinct(DataRowComparer.Default);
//使用与flatDataTable相同的结构创建新的独立表
DataTable distinctFlatDataTable=flatDataTable.Clone();
distinctFlatDataTable.Rows.Clear();
//将所有行推送到不同的表中。
//注意:主键1和主键2将有两个不同的列。在分组行中,
//主键1或主键2可以有空值。因此,将所有主键2值复制到
//主键1仅当主键1值为空时,然后删除主键2。因此,最后
//我们将只获得一个perimary密钥。请确保未删除的密钥必须存在于中
foreach(数据行中的行)
{
if(string.IsNullOrEmpty(行[table1PrimaryKey].ToString())
行[table1PrimaryKey]=行[table2PrimaryKey];
if(string.IsNullOrEmpty(行[CaptureBusDateColumn].ToString())
行[CaptureBusDateColumn]=\u businessDate;
if(string.IsNullOrEmpty(行[CaptureUserIDColumn].ToString())
行[CaptureUserIDColumn]=行[StatsUserIDColumn];
distinctFlatDataTable.ImportRow(行);
}
//根据主键对表进行排序。
DataTable sortedFinaltable=(来自distinctFlatDataTable.AsEnumerable()中的orderRow)
orderby orderRow.Field(table1PrimaryKey)
选择orderRow).CopyToDataTable();
//删除主键2,因为我们已经将其复制到主键1
sortedFinaltable.Columns.Remove(table2PrimaryKey);
返回replacenalls(sortedFinaltable,“0”);
}
///
///用指定的字符串替换数据表中的所有空值
///
///
///
///
专用数据表
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();
}