/// <summary>
/// 获取 DateTimeOffset 类型的 SQL 片断
/// </summary>
/// <param name="value">值</param>
/// <param name="dbType">数据类型</param>
/// <param name="scale">小数位</param>
/// <returns></returns>
protected override string GetSqlValueOfDateTimeOffset(object value, object dbType, int?scale)
{
// 默认精度6
string format = "yyyy-MM-dd HH:mm:ss.ffffff";
if (NpgUtils.IsDateTimeOffset(dbType))
{
string s = string.Empty;
if (scale != null && scale.Value > 0)
{
s = string.Empty.PadLeft(scale.Value > 6 ? 6 : scale.Value, 'f');
}
if (!string.IsNullOrEmpty(s))
{
format = string.Format("yyyy-MM-dd HH:mm:ss.{0}", s);
}
}
string myDateTime = ((DateTimeOffset)value).DateTime.ToString(format);
string myOffset = ((DateTimeOffset)value).Offset.ToString(@"hh\:mm");
myOffset = string.Format("{0}{1}", ((DateTimeOffset)value).Offset < TimeSpan.Zero ? '-' : '+', myOffset);
string result = string.Format("'{0}{1}'::TIMESTAMPTZ ", myDateTime, myOffset);
return(result);
// Npgsql 的显示都是以本地时区显示的？###
}
/// <summary>
/// 访问 ToString 方法
/// </summary>
/// <param name="node">即将访问的表达式</param>
protected override Expression VisitToStringImpl(Expression node)
{
// => a.ID.ToString()
// 字符串不进行转换
if (node == null || node.Type == typeof(string))
{
return(_visitor.Visit(node));
}
// 其它类型转字符串
bool isDate =
node.Type == typeof(TimeSpan) ||
node.Type == typeof(TimeSpan?) ||
node.Type == typeof(DateTime) ||
node.Type == typeof(DateTime?) ||
node.Type == typeof(DateTimeOffset) ||
node.Type == typeof(DateTimeOffset?);
if (isDate)
{
_builder.Append("TO_CHAR(");
_visitor.Visit(node);
string format = string.Empty;
ColumnAttribute c = _visitedMark.Current != null?TypeUtils.GetColumnAttribute(_visitedMark.Current.Member, _visitedMark.Current.ReflectedType) : null;
if (c != null && NpgUtils.IsTime(c.DbType))
{
format = "hh24:mi:ss.us";
}
else if (c != null && NpgUtils.IsDate(c.DbType))
{
format = "yyyy-mm-dd";
}
else if (c != null && (NpgUtils.IsDateTime(c.DbType) || NpgUtils.IsDateTime2(c.DbType)))
{
format = "yyyy-mm-dd hh24:mi:ss.us";
}
else if (c != null && NpgUtils.IsDateTimeOffset(c.DbType))
{
format = "yyyy-mm-dd hh24:mi:ss.us TZH:TZM";
}
// 没有显式指定数据类型，则根据表达式的类型来判断
if (string.IsNullOrEmpty(format))
{
if (node.Type == typeof(TimeSpan) || node.Type == typeof(TimeSpan?))
{
format = "hh24:mi:ss.us";
}
else if (node.Type == typeof(DateTime) || node.Type == typeof(DateTime?))
{
format = "yyyy-mm-dd hh24:mi:ss.us";
}
else if (node.Type == typeof(DateTimeOffset) || node.Type == typeof(DateTimeOffset?))
{
format = "yyyy-mm-dd hh24:mi:ss.us TZH:TZM";
}
}
if (!string.IsNullOrEmpty(format))
{
_builder.Append(",'");
_builder.Append(format);
_builder.Append("'");
}
_builder.Append(')');
}
else if (node.Type == typeof(byte[]))
{
_builder.Append("ENCODE(");
_visitor.Visit(node);
_builder.Append(",'hex')");
}
else
{
_builder.Append("CAST(");
_visitor.Visit(node);
_builder.Append(" AS VARCHAR)");
}
return(node);
}