以前在处理DateTime的时候,为了屏蔽不同数据库的差异,经常将DateTime保存成字符串,只要服务器不切换本地化表示方法,这种方案肯定是没有问题的。只是在读取和保存的时候需要各做一次转换,(实际上System.Data.Sqlite也会做类似的事情,因此性能上几乎没有差异)。
这种方法延续到Sqlite一样没有问题,最近看一个开源项目,里面直接用的DateTime,里面用了Utc格式,后来在日志中发现总是有格式异常的报警,仔细调阅了一下日志发现问题都是一样的,根源指到了System.Data.Sqlite。
System.FormatException: String was not recognized as a valid DateTime.
at System.DateTimeParse.ParseExactMultiple(String s, String[] formats, DateTimeFormatInfo dtfi, DateTimeStyles style)
at System.DateTime.ParseExact(String s, String[] formats, IFormatProvider provider, DateTimeStyles style)
at System.Data.SQLite.SQLiteConvert.ToDateTime(String dateText)
at System.Data.SQLite.SQLite3.GetDateTime(SQLiteStatement stmt, Int32 index)
at System.Data.SQLite.SQLite3.GetValue(SQLiteStatement stmt, Int32 index, SQLiteType typ)
at System.Data.SQLite.SQLiteDataReader.GetValue(Int32 i)
对应源代码为:
Sqlite3.cs
internal
override
DateTime GetDateTime(SQLiteStatement stmt,
int
index)
{
#if
!SQLITE_STANDARD
int
len;
return
ToDateTime(UnsafeNativeMethods.sqlite3_column_text_interop(stmt._sqlite_stmt, index,
out
len), len);
#else
return
ToDateTime(UnsafeNativeMethods.sqlite3_column_text(stmt._sqlite_stmt, index),
-
1
);
#endif
}
SQLiteConvert.cs
///
<summary>
///
Converts a string into a DateTime, using the current DateTimeFormat specified for the connection when it was opened.
///
</summary>
///
<remarks>
///
Acceptable ISO8601 DateTime formats are:
///
yyyy-MM-dd HH:mm:ss
///
yyyyMMddHHmmss
///
yyyyMMddTHHmmssfffffff
///
yyyy-MM-dd
///
yy-MM-dd
///
yyyyMMdd
///
HH:mm:ss
///
THHmmss
///
</remarks>
///
<param name="dateText">
The string containing either a Tick value, a JulianDay double, or an ISO8601-format string
</param>
///
<returns>
A DateTime value
</returns>
public
DateTime ToDateTime(
string
dateText)
{
switch
(_datetimeFormat)
{
case
SQLiteDateFormats.Ticks:
return
new
DateTime(Convert.ToInt64(dateText, CultureInfo.InvariantCulture));
case
SQLiteDateFormats.JulianDay:
return
ToDateTime(Convert.ToDouble(dateText, CultureInfo.InvariantCulture));
default
:
return
DateTime.ParseExact(dateText, _datetimeFormats, DateTimeFormatInfo.InvariantInfo, DateTimeStyles.None);
}
}
问题就出现在这里面,ISO8601规范,无非就有两种办法,
一种是在存储的时候datetime格式要遵守ISO8601格式规范,即转码.ToString("S");
另外一种方法就是扩展_datetimeFormats,让其支持其他格式。
原始定义为:
///
<summary>
///
An array of ISO8601 datetime formats we support conversion from
///
</summary>
private
static
string
[] _datetimeFormats
=
new
string
[] {
"
THHmmss
"
,
"
THHmm
"
,
"
HH:mm:ss
"
,
"
HH:mm
"
,
"
HH:mm:ss.FFFFFFF
"
,
"
yy-MM-dd
"
,
"
yyyy-MM-dd
"
,
"
yyyy-MM-dd HH:mm:ss.FFFFFFF
"
,
"
yyyy-MM-dd HH:mm:ss
"
,
"
yyyy-MM-dd HH:mm
"
,
"
yyyy-MM-ddTHH:mm:ss.FFFFFFF
"
,
"
yyyy-MM-ddTHH:mm
"
,
"
yyyy-MM-ddTHH:mm:ss
"
,
"
yyyyMMddHHmmss
"
,
"
yyyyMMddHHmm
"
,
"
yyyyMMddTHHmmssFFFFFFF
"
,
"
yyyyMMdd
"
};
修改后的定义为:
///
<summary>
///
An array of ISO8601 datetime formats we support conversion from
///
</summary>
private
static
string
[] _datetimeFormats
=
new
string
[] {
"
THHmmss
"
,
"
THHmm
"
,
"
HH:mm:ss
"
,
"
HH:mm
"
,
"
HH:mm:ss.FFFFFFF
"
,
"
yy-M-d
"
,
"
yy-M-dd
"
,
"
yy-MM-dd
"
,
"
yyyy-M-d
"
,
"
yyyy-M-dd
"
,
"
yyyy-MM-dd
"
,
"
yyyy-M-d H:mm:ss.FFFFFFF
"
,
"
yyyy-M-d H:mm:ss
"
,
"
yyyy-M-d H:mm
"
,
"
yyyy-M-d HH:mm:ss.FFFFFFF
"
,
"
yyyy-M-d HH:mm:ss
"
,
"
yyyy-M-d HH:mm
"
,
"
yyyy-M-dTHH:mm:ss.FFFFFFF
"
,
"
yyyy-M-dTHH:mm
"
,
"
yyyy-M-dTHH:mm:ss
"
,
"
yyyy-M-dd H:mm:ss.FFFFFFF
"
,
"
yyyy-M-dd H:mm:ss
"
,
"
yyyy-M-dd H:mm
"
,
"
yyyy-M-dd HH:mm:ss.FFFFFFF
"
,
"
yyyy-M-dd HH:mm:ss
"
,
"
yyyy-M-dd HH:mm
"
,
"
yyyy-M-ddTHH:mm:ss.FFFFFFF
"
,
"
yyyy-M-ddTHH:mm
"
,
"
yyyy-M-ddTHH:mm:ss
"
,
"
yyyy-MM-dd H:mm:ss.FFFFFFF
"
,
"
yyyy-MM-dd H:mm:ss
"
,
"
yyyy-MM-dd H:mm
"
,
"
yyyy-MM-dd HH:mm:ss.FFFFFFF
"
,
"
yyyy-MM-dd HH:mm:ss
"
,
"
yyyy-MM-dd HH:mm
"
,
"
yyyy-MM-ddTHH:mm:ss.FFFFFFF
"
,
"
yyyy-MM-ddTHH:mm
"
,
"
yyyy-MM-ddTHH:mm:ss
"
,
"
yyyyMMddHHmmss
"
,
"
yyyyMMddHHmm
"
,
"
yyyyMMddTHHmmssFFFFFFF
"
,
"
yyyyMMdd
"
,
"
yy/M/d
"
,
"
yy/M/dd
"
,
"
yy/MM/dd
"
,
"
yyyy/M/d
"
,
"
yyyy/M/dd
"
,
"
yyyy/MM/dd
"
,
"
yyyy/M/d H:mm:ss.FFFFFFF
"
,
"
yyyy/M/d H:mm:ss
"
,
"
yyyy/M/d H:mm
"
,
"
yyyy/M/d HH:mm:ss.FFFFFFF
"
,
"
yyyy/M/d HH:mm:ss
"
,
"
yyyy/M/d HH:mm
"
,
"
yyyy/M/dTHH:mm:ss.FFFFFFF
"
,
"
yyyy/M/dTHH:mm
"
,
"
yyyy/M/dTHH:mm:ss
"
,
"
yyyy/M/dd H:mm:ss.FFFFFFF
"
,
"
yyyy/M/dd H:mm:ss
"
,
"
yyyy/M/dd H:mm
"
,
"
yyyy/M/dd HH:mm:ss.FFFFFFF
"
,
"
yyyy/M/dd HH:mm:ss
"
,
"
yyyy/M/dd HH:mm
"
,
"
yyyy/M/ddTHH:mm:ss.FFFFFFF
"
,
"
yyyy/M/ddTHH:mm
"
,
"
yyyy/M/ddTHH:mm:ss
"
,
"
yyyy/MM/dd H:mm:ss.FFFFFFF
"
,
"
yyyy/MM/dd H:mm:ss
"
,
"
yyyy/MM/dd H:mm
"
,
"
yyyy/MM/dd HH:mm:ss.FFFFFFF
"
,
"
yyyy/MM/dd HH:mm:ss
"
,
"
yyyy/MM/dd HH:mm
"
,
"
yyyy/MM/ddTHH:mm:ss.FFFFFFF
"
,
"
yyyy/MM/ddTHH:mm
"
,
"
yyyy/MM/ddTHH:mm:ss
"
};
然后重新编译一下,就OK了,您也可以根据具体的使用情况进行扩展。
最后还有一种办法,就是Ticks,这种方案需要在连接字符串上设置,DateTimeFormat=Ticks(默认是ISO8601),这种方案和最开始的方案类似,第一种方案是转换为字符串,这种是转换为int64,然后由系统的转换方法实现转换。
修改后的Sqlite,/Files/chinull/sqlite.rar