C# CDate的行为有多奇怪?
我发现C# CDate的行为有多奇怪?,c#,sql,database,ms-access,date-conversion,C#,Sql,Database,Ms Access,Date Conversion,我发现CDate函数在以下代码中有一个奇怪的行为: private void button1_Click(object sender, EventArgs e) { OleDbConnection connection = new OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;User ID=Admin;Data Source=" + Application.StartupPath + @"\db.md
CDate
函数在以下代码中有一个奇怪的行为:
private void button1_Click(object sender, EventArgs e)
{
OleDbConnection connection = new OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;User ID=Admin;Data Source=" + Application.StartupPath + @"\db.mdb" + ";Persist Security Info=False");
{
OleDbDataAdapter adapterA = new OleDbDataAdapter("SELECT CDate(#01/05/2013#) AS TheDate", connection);
DataTable dataTableA = new DataTable();
adapterA.Fill(dataTableA);
DateTime dateTimeA = (DateTime)dataTableA.Rows[0]["TheDate"]; // get 1
MessageBox.Show(dateTimeA.Month.ToString());
} //these to ensure that I did not use the variables in the next block /^-^\ .
{
OleDbDataAdapter adapterB = new OleDbDataAdapter("SELECT CDate(#13/05/2013#) AS TheDate", connection);
DataTable dataTableB = new DataTable();
adapterB.Fill(dataTableB);
DateTime dateTimeB = (DateTime)dataTableB.Rows[0]["TheDate"]; // get 5
MessageBox.Show(dateTimeB.Month.ToString());
}
}
我知道,如果值大于12,则
为什么微软没有在MSDN中解释这一点?是的,你是对的。CDate尝试将大于12的月值视为日值 你可以试试这个
private bool IsDate(String inputDate)
{
DateTime dt;
Return DateTime.TryParse(inputDate,out dt);
}
也许这只是VB.NET和SQL之间的一个奇怪的巧合,但是不划界日期文字吗?因此,
CDate
与此无关;日期文字会自动更改格式。“无论如何都有效”:PAgree with@minitech如果您想要CDate,请使用字符串。此外,年、月、日也可以避免区域设置方面的问题。