/// <summary>
/// Returns the Statement for the <see cref="SelectDbOperation"/>.
/// </summary>
/// <returns>A string containing the select statement</returns>
public override string GetStatement()
{
// Make sure it's ok to run the statement
this.PreStatementValidation();
// For performance issues, use the String Builder Class
StringBuilder sbStatement = new StringBuilder();
#region Select
// Display Fields
StringBuilder sbSelect = new StringBuilder("SELECT ");
if (Distinct)
{
sbSelect.Append("DISTINCT ");
}
// Check all Non-Aggregate Fields
if (SelectFields.Count == 0)
{
// Select All Fields
sbSelect.Append('*');
sbSelect.AppendLine();
}
else
{
// For formatting purposes, add a line right after the select
sbSelect.AppendLine();
// Select Specific Fields
sbSelect.AppendLine(String.Join(",\r\n", from field in SelectFields
select String.Concat(String.Empty.PadLeft(7, ' '),
field.Type == FieldTypes.Display ?
Dialect.FormatField((DisplayField)field) : Dialect.FormatField((AggregateField)field))));
}
#endregion Select
#region Select Aggregates
//// Check all Aggregate Fields
//if (SelectFields.Count(field => field.Type == FieldTypes.Aggregate) > 0)
//{
// sbSelect.AppendLine(String.Join(",\r\n", from field in SelectFields
// where field.Type == FieldTypes.Aggregate
// select String.Concat(String.Empty.PadLeft(7, ' '), Dialect.FormatField((AggregateField)field))));
//}
#endregion Select Aggregates
#region From
// From Statement
sbSelect.Append(" FROM ");
if (base.Tables == null)
{
throw new NullReferenceException($"Tables are not defined for the {nameof(SelectDbOperation)}.");
}
if (base.Tables.Count == 0)
{
throw new Exception($"There are no tables assigned for the {nameof(SelectDbOperation)}.");
}
if (base.Tables.Count == 1)
{
// Append Single Table
sbSelect.AppendLine(base.Dialect.FormatTable(base.Tables[0]));
}
else
{
// Append Multiple Tables Separated by a Comma
sbSelect.AppendLine();
sbSelect.AppendLine(String.Join(",\r\n", from tbl in base.Tables
select String.Concat(String.Empty.PadLeft(7, ' '), Dialect.FormatTable(tbl))));
}
#endregion From
#region Joins
//TODO: Implement SelectDbOperation -> Joins
#endregion Joins
#region Where
//TODO: Implement SelectDbOperation -> Where
// Add Filters, if needed
if (Where?.Count > 0)
{
sbSelect.AppendLine(" WHERE ");
}
#endregion Where
#region Group By
// Group By Fields
if (GroupBy)
{
sbSelect.AppendLine("GROUP BY");
if (SelectFields?.Count(field => field.Type == FieldTypes.Display) > 0)
{
// Add all display fields but make sure to not have the alternate name on it
sbSelect.AppendLine(String.Join(",\r\n", from field in SelectFields
where field.Type == FieldTypes.Display
select String.Concat(String.Empty.PadLeft(9, ' '), Dialect.FormatField(new DisplayField(field.Name, field.TableAlias)))));
}
}
#endregion Group By
#region Having
//TODO: Implement SelectDbOperation -> Having
#endregion Having
// Return the Final Statement
return(sbSelect.ToString());
}