public static int Update(this IMutableTable mutableTable, IQuery context, ITable table,
IEnumerable <SqlAssignExpression> assignList, int limit)
{
// Get the rows from the input table.
var rowSet = new List <int>();
var e = table.GetEnumerator();
while (e.MoveNext())
{
rowSet.Add(e.Current.RowId.RowNumber);
}
// HACKY: Find the first column of this table in the search table. This
// will allow us to generate a row set of only the rows in the search
// table.
int firstColumn = table.FindColumn(mutableTable.GetResolvedColumnName(0));
if (firstColumn == -1)
{
throw new InvalidOperationException("Search table does not contain any " +
"reference to table being updated from");
}
// Convert the row_set to this table's domain.
rowSet = table.ResolveRows(firstColumn, rowSet, mutableTable).ToList();
// NOTE: Assume there's no duplicate rows.
// If limit less than zero then limit is whole set.
if (limit < 0)
{
limit = Int32.MaxValue;
}
// Update each row in row set in turn up to the limit.
int len = System.Math.Min(rowSet.Count, limit);
int updateCount = 0;
for (int i = 0; i < len; ++i)
{
int toUpdate = rowSet[i];
// Make a row object from this row (plus keep the original intact
// in case we need to roll back to it).
var row = mutableTable.GetRow(toUpdate);
row.SetFromTable();
// Run each assignment on the row.
foreach (var assignment in assignList)
{
row.EvaluateAssignment(assignment, context);
}
// Update the row
mutableTable.UpdateRow(row);
++updateCount;
}
if (updateCount > 0)
{
// Perform a referential integrity check on any changes to the table.
mutableTable.AssertConstraints();
}
return(updateCount);
}
