/// <inheritdoc/>
protected override SqlProvider VisitExcept(ExceptProvider provider)
{
var left = Compile(provider.Left);
var right = Compile(provider.Right);
var leftSelect = left.Request.Statement;
var keepOrderForLeft = (leftSelect.HasLimit || leftSelect.HasOffset) && providerInfo.Supports(ProviderFeatures.PagingRequiresOrderBy);
if (!keepOrderForLeft)
{
leftSelect.OrderBy.Clear();
}
var rightSelect = right.Request.Statement;
var keepOrderForRight = (leftSelect.HasLimit || leftSelect.HasOffset) && providerInfo.Supports(ProviderFeatures.PagingRequiresOrderBy);
if (!keepOrderForRight)
{
rightSelect.OrderBy.Clear();
}
var result = SqlDml.Except(leftSelect, rightSelect);
var queryRef = SqlDml.QueryRef(result);
SqlSelect query = SqlDml.Select(queryRef);
query.Columns.AddRange(queryRef.Columns.Cast <SqlColumn>());
return(CreateProvider(query, provider, left, right));
}
public void ExceptTest()
{
SqlSelect s1 = SqlDml.Select(SqlDml.TableRef(Catalog.Schemas["main"].Tables["track"]));
s1.Columns.Add(SqlDml.Asterisk);
SqlSelect s2 = SqlDml.Select(SqlDml.TableRef(Catalog.Schemas["main"].Tables["track"]));
s2.Columns.Add(SqlDml.Asterisk);
SqlSelect s3 = SqlDml.Select(SqlDml.TableRef(Catalog.Schemas["main"].Tables["track"]));
s3.Columns.Add(SqlDml.Asterisk);
Console.WriteLine(sqlDriver.Compile(s1.Except(s2)).GetCommandText());
Console.WriteLine(sqlDriver.Compile(s1.Except(s2).Except(s3)).GetCommandText());
Console.WriteLine(sqlDriver.Compile(s1.Except(s2.Except(s3))).GetCommandText());
Console.WriteLine(sqlDriver.Compile(SqlDml.Except(s1, s2)).GetCommandText());
Console.WriteLine(sqlDriver.Compile(SqlDml.Except(s1, s1.Except(s2))).GetCommandText());
Console.WriteLine(sqlDriver.Compile(SqlDml.Except(s1.Except(s2), s1)).GetCommandText());
Console.WriteLine(sqlDriver.Compile(SqlDml.Except(s1.Except(s2), s1.Except(s2))).GetCommandText());
}
public SqlQueryExpression Except(ISqlQueryExpression operand)
{
return(SqlDml.Except(this, operand));
}