private void AppendWhere(UnionSubQuery unionSubQuery, string newWhereStr)
{
SQLExpressionAnd resultWhere;
// parse and prepare new WHERE expression
SQLExpressionItem newWhere = ParseExpression(newWhereStr);
// if there are no new expression - nothing to do
if (newWhere == null)
{
return;
}
// extract old WHERE expression
SQLExpressionItem oldWhere = unionSubQuery.QueryColumnList.GetConditionTree(new[] { ConditionType.Where });
// normalize old WHERE expression
if (oldWhere != null)
{
oldWhere.RestoreColumnPrefixRecursive(true);
}
// simplify old WHERE expression
if (oldWhere != null)
{
// if old WHERE is a collection of ORed or ANDed expressions
// with only one expression in the list - remove the external list
while (oldWhere is SQLExpressionLogicalCollection &&
((SQLExpressionLogicalCollection)oldWhere).Count == 1)
{
using (SQLExpressionLogicalCollection tmp = (SQLExpressionLogicalCollection)oldWhere)
{
oldWhere = tmp.Extract(0);
}
}
}
// combine old and new WHERE expressions
resultWhere = new SQLExpressionAnd(queryBuilder1.SQLContext);
if (oldWhere != null)
{
resultWhere.Add(oldWhere);
}
resultWhere.Add(newWhere);
// fix up combined WHERE expression
FixupExpression(unionSubQuery, resultWhere);
// defer SQL updates
unionSubQuery.BeginUpdate();
try
{
// clear old WHERE expression
ClearWhere(unionSubQuery);
// load new WHERE expression (if exists)
unionSubQuery.QueryColumnList.LoadConditionFromAST(resultWhere, ConditionType.Where);
}
finally
{
// enable SQL updates
unionSubQuery.EndUpdate();
}
}
