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Radarr/Marr.Data/QGen/RowCountQueryDecorator.cs

124 lines
3.7 KiB

using System.Text;
namespace Marr.Data.QGen
{
public class RowCountQueryDecorator : IQuery
{
private SelectQuery _innerQuery;
public RowCountQueryDecorator(SelectQuery innerQuery)
{
_innerQuery = innerQuery;
}
public string Generate()
{
// Decide which type of paging query to create
if (_innerQuery.IsView || _innerQuery.IsJoin)
{
return ComplexRowCount();
}
else
{
return SimpleRowCount();
}
}
/// <summary>
/// Generates a row count query for a multiple table joined query (groups by the parent entity).
/// </summary>
/// <returns></returns>
private string ComplexRowCount()
{
// Create paged query
StringBuilder sql = new StringBuilder();
sql.AppendLine("WITH GroupCTE AS (");
sql.Append("SELECT ").AppendLine(BuildBaseTablePKColumns());
BuildGroupColumn(sql);
_innerQuery.BuildFromClause(sql);
_innerQuery.BuildJoinClauses(sql);
_innerQuery.BuildWhereClause(sql);
sql.AppendLine(")");
BuildSelectCountClause(sql);
sql.AppendLine("FROM GroupCTE");
sql.AppendLine("WHERE GroupRow = 1");
return sql.ToString();
}
/// <summary>
/// Generates a row count query for a single table query (no joins).
/// </summary>
/// <returns></returns>
private string SimpleRowCount()
{
StringBuilder sql = new StringBuilder();
BuildSelectCountClause(sql);
_innerQuery.BuildFromClause(sql);
_innerQuery.BuildJoinClauses(sql);
_innerQuery.BuildWhereClause(sql);
return sql.ToString();
}
private void BuildGroupColumn(StringBuilder sql)
{
string baseTablePKColumns = BuildBaseTablePKColumns();
sql.AppendFormat(", ROW_NUMBER() OVER (PARTITION BY {0} ORDER BY {1}) As GroupRow ", baseTablePKColumns, baseTablePKColumns);
}
private string BuildBaseTablePKColumns()
{
Table baseTable = GetBaseTable();
StringBuilder sb = new StringBuilder();
foreach (var col in baseTable.Columns.PrimaryKeys)
{
if (sb.Length > 0)
sb.AppendLine(", ");
string colName = _innerQuery.IsView ?
_innerQuery.NameOrAltName(col.ColumnInfo) :
col.ColumnInfo.Name;
sb.AppendFormat(_innerQuery.Dialect.CreateToken(string.Concat(baseTable.Alias, ".", colName)));
}
return sb.ToString();
}
private void BuildSelectCountClause(StringBuilder sql)
{
sql.AppendLine("SELECT COUNT(*)");
}
private Table GetBaseTable()
{
Table baseTable = null;
if (_innerQuery.Tables[0] is View)
{
baseTable = (_innerQuery.Tables[0] as View).Tables[0];
}
else
{
baseTable = _innerQuery.Tables[0];
}
return baseTable;
}
}
}
/*
WITH GroupCTE AS
(
SELECT [t0].[ID],[t0].[OrderName],[t1].[ID] AS OrderItemID,[t1].[OrderID],[t1].[ItemDescription],[t1].[Price],
ROW_NUMBER() OVER (PARTITION BY [t0].[ID] ORDER BY [t0].[OrderName]) As GroupRow
FROM [Order] [t0]
LEFT JOIN [OrderItem] [t1] ON (([t0].[ID] = [t1].[OrderID]))
--WHERE (([t0].[OrderName] = @P0))
)
SELECT * FROM GroupCTE
WHERE GroupRow = 1
*/