private void DeleteRows(long[] ids, AbstractSqlModel tableModel)
{
Debug.Assert(ids != null);
Debug.Assert(tableModel != null);
var ctx = this.DbDomain.CurrentSession;
if (tableModel.Hierarchy)
{
UpdateTreeForDeletion(ids, tableModel);
}
else
{
var sql = new SqlString(
"delete from ", tableModel.quotedTableName,
@" where ""_id"" in (", ids.ToCsv(), ")");
var rowCount = ctx.DataContext.Execute(sql);
if (rowCount != ids.Count())
{
var msg = string.Format("Failed to delete model '{0}'", tableModel.Name);
throw new SlipStream.Exceptions.DataException(msg);
}
}
}
public TableMigrator(IServiceContext tc, AbstractSqlModel model)
{
if (tc == null)
{
throw new ArgumentNullException("session");
}
if (model == null)
{
throw new ArgumentNullException("model");
}
this.model = model;
this.context = tc;
}
private void UpdateTreeForDeletion(long[] ids, AbstractSqlModel tableModel)
{
var records =
from r in tableModel.ReadInternal(ids, HierarchyFields)
select new
{
ID = (long)r[IdFieldName],
Left = (long)r[LeftFieldName],
Right = (long)r[RightFieldName]
};
//这里是做化简，如果 ids 里面有的节点 id 已经是被其它节点包含了，那么就去掉
//TODO 这里是个 O(n^2) 的复杂度，应该可以用二分搜索优化的
//先删最右侧的很重要，否则 parentRecords 是保存在内存里的，没法反应出后面的 update 语句带来的更改
var parentRecords =
from r in records
where !records.Any(i => i.Left <r.Left && i.Right> r.Right)
orderby r.Right descending
select r;
var ctx = this.DbDomain.CurrentSession;
ctx.DataContext.LockTable(tableModel.TableName);
foreach (var record in parentRecords)
{
var width = record.Right - record.Left;
//删除指定ID节点及其下面包含的子孙节点
var sql = new SqlString(
"delete from ", tableModel.quotedTableName,
" where ", LeftFieldName,
" between ", Parameter.Placeholder, " and ", Parameter.Placeholder);
ctx.DataContext.Execute(sql, record.Left, record.Right);
//更新所有右边节点的 _left 与 _right
var sqlUpdate1 = String.Format(CultureInfo.InvariantCulture,
"update {0} set _right = _right - {1} where _right > {2}",
tableModel.quotedTableName, width + 1, record.Right);
var sqlUpdate2 = String.Format(CultureInfo.InvariantCulture,
"update {0} set _left = _left - {1} where _left > {2}",
tableModel.quotedTableName, width + 1, record.Left);
ctx.DataContext.Execute(SqlString.Parse(sqlUpdate1));
ctx.DataContext.Execute(SqlString.Parse(sqlUpdate2));
}
}