public override DbExpression Visit(DbSqlQueryExpression exp)
{
if (exp.TakeCount != null)
{
DbSqlQueryExpression newSqlQuery = CloneWithoutLimitInfo(exp, "TTAKE");
if (exp.SkipCount == null)
{
AppendLimitCondition(newSqlQuery, exp.TakeCount.Value);
}
else
{
AppendLimitCondition(newSqlQuery, exp.TakeCount.Value + exp.SkipCount.Value);
newSqlQuery.SkipCount = exp.SkipCount.Value;
}
newSqlQuery.IsDistinct = exp.IsDistinct;
newSqlQuery.Accept(this);
return(exp);
}
else if (exp.SkipCount != null)
{
DbSqlQueryExpression subSqlQuery = CloneWithoutLimitInfo(exp, "TSKIP");
string row_numberName = GenRowNumberName(subSqlQuery.ColumnSegments);
DbColumnSegment row_numberSeg = new DbColumnSegment(OracleSemantics.DbMemberExpression_ROWNUM, row_numberName);
subSqlQuery.ColumnSegments.Add(row_numberSeg);
DbTable table = new DbTable("T");
DbSqlQueryExpression newSqlQuery = WrapSqlQuery(subSqlQuery, table, exp.ColumnSegments);
DbColumnAccessExpression columnAccessExp = new DbColumnAccessExpression(table, DbColumn.MakeColumn(row_numberSeg.Body, row_numberName));
newSqlQuery.Condition = DbExpression.GreaterThan(columnAccessExp, DbExpression.Constant(exp.SkipCount.Value));
newSqlQuery.IsDistinct = exp.IsDistinct;
newSqlQuery.Accept(this);
return(exp);
}
this.BuildGeneralSql(exp);
return(exp);
}
protected override Expression VisitBinary(BinaryExpression node)
{
var expression = base.VisitBinary(node) as BinaryExpression;
DbExpression dbExpression;
// Need special handling for comparisons against the null constant. If we don't translate these
// using an "IsNull" expression, EF will convert it literally as "= null" which doesn't work in SQL Server.
if (IsNullConstantExpression(expression.Right))
{
dbExpression = MapNullComparison(expression.Left, expression.NodeType);
}
else if (IsNullConstantExpression(expression.Left))
{
dbExpression = MapNullComparison(expression.Right, expression.NodeType);
}
else
{
DbExpression leftExpression = GetDbExpressionForExpression(expression.Left);
DbExpression rightExpression = GetDbExpressionForExpression(expression.Right);
switch (expression.NodeType)
{
case ExpressionType.Equal:
// DbPropertyExpression = class property that has been mapped to a database column
// DbParameterReferenceExpression = lambda parameter
if (IsNullableExpressionOfType <DbPropertyExpression>(leftExpression) && IsNullableExpressionOfType <DbParameterReferenceExpression>(rightExpression))
{
dbExpression = CreateEqualComparisonOfNullablePropToNullableParam(leftExpression, rightExpression);
}
else if (IsNullableExpressionOfType <DbPropertyExpression>(rightExpression) && IsNullableExpressionOfType <DbParameterReferenceExpression>(leftExpression))
{
dbExpression = CreateEqualComparisonOfNullablePropToNullableParam(rightExpression, leftExpression);
}
else
{
dbExpression = leftExpression.Equal(rightExpression);
}
break;
case ExpressionType.NotEqual:
dbExpression = leftExpression.NotEqual(rightExpression);
break;
case ExpressionType.GreaterThan:
dbExpression = leftExpression.GreaterThan(rightExpression);
break;
case ExpressionType.GreaterThanOrEqual:
dbExpression = leftExpression.GreaterThanOrEqual(rightExpression);
break;
case ExpressionType.LessThan:
dbExpression = leftExpression.LessThan(rightExpression);
break;
case ExpressionType.LessThanOrEqual:
dbExpression = leftExpression.LessThanOrEqual(rightExpression);
break;
case ExpressionType.AndAlso:
dbExpression = leftExpression.And(rightExpression);
break;
case ExpressionType.OrElse:
dbExpression = leftExpression.Or(rightExpression);
break;
default:
throw new NotImplementedException(string.Format("Unhandled NodeType of {0} in LambdaToDbExpressionVisitor.VisitBinary", expression.NodeType));
}
}
MapExpressionToDbExpression(expression, dbExpression);
return(expression);
}
