如何根据 c# 中的变量选择要使用的 where 子句？答案

【问题标题】：How to select which where clause to use based off a variable in c#?如何根据 c# 中的变量选择要使用的 where 子句？
【发布时间】：2019-09-12 22:29:24
【问题描述】：

我正在尝试压缩我的代码，以便根据 c# 变量选择用户想要使用的 where 子句。

我尝试过使用参数和我在网上看到的其他一些想法，但无法使其发挥作用。

if (btnUseDateRange.Text == "Disabled")
{
 var queryTestedControls =
 (from t in dbContext.UUT_RESULT
 where t.PART_NAME.Contains(ControlSelected)
 && t.UUT_SERIAL_NUMBER.CompareTo(BarcodeStart) >= 0
 && t.UUT_SERIAL_NUMBER.CompareTo(BarcodeEnd) <= 0
 select t.UUT_SERIAL_NUMBER).Count();

 var queryPassedControls =
 (from t in dbContext.UUT_RESULT
 where t.PART_NAME.Contains(ControlSelected)
 && t.UUT_SERIAL_NUMBER.CompareTo(BarcodeStart) >= 0
 && t.UUT_SERIAL_NUMBER.CompareTo(BarcodeEnd) <= 0
 && t.UUT_STATUS == "Passed"
 select t.UUT_SERIAL_NUMBER).Count();

 lblTested.Text = queryTestedControls.ToString();
 lblPassed.Text = queryPassedControls.ToString();
}
else if (btnUseDateRange.Text == "Enabled")
{
 var queryTestedControls =
 (from t in dbContext.UUT_RESULT
 where t.PART_NAME.Contains(ControlSelected)
 && t.START_DATE_TIME >= DateStart
 && t.START_DATE_TIME <= DateEnd
 select t.UUT_SERIAL_NUMBER).Count();

 var queryPassedControls =
 (from t in dbContext.UUT_RESULT
 where t.PART_NAME.Contains(ControlSelected)
 && t.START_DATE_TIME >= DateStart
 && t.START_DATE_TIME <= DateEnd
 && t.UUT_STATUS == "Passed"
 select t.UUT_SERIAL_NUMBER).Count();

 lblTested.Text = queryTestedControls.ToString();
 lblPassed.Text = queryPassedControls.ToString();
}

我的代码会很长，因为我正在计算 Passed、Failed、Aborted 和 Other。有没有办法压缩查询？根据 if 语句中的按钮，用户选择使用条形码范围或日期时间范围进行查询。

【问题讨论】：

标签： c# sql asp.net entity-framework

【解决方案1】：

略短

var queryTestedControls = from t in dbContext.UUT_RESULT
                          where t.PART_NAME.Contains(ControlSelected)
                          select t;
var queryPassedControls = from t in dbContext.UUT_RESULT
                          where t.PART_NAME.Contains(ControlSelected)
                          select t;                                 

if (btnUseDateRange.Text == "Disabled")
{
    lblTested.Text = queryTestedControls.Where(t => t.UUT_SERIAL_NUMBER.CompareTo(BarcodeStart) >= 0 &&
                                t.UUT_SERIAL_NUMBER.CompareTo(BarcodeEnd) <= 0).Count().ToString();

    lblPassed.Text = queryPassedControls.Where(t => t.UUT_SERIAL_NUMBER.CompareTo(BarcodeStart) >= 0 &&
                                t.UUT_SERIAL_NUMBER.CompareTo(BarcodeEnd) <= 0 &&
                                t.UUT_STATUS == "Passed").Count().ToString();
}
else if (btnUseDateRange.Text == "Enabled")
{
    lblTested.Text = queryTestedControls.Where(t => t.START_DATE_TIME >= DateStart &&
                                t.START_DATE_TIME <= DateEnd).Count().ToString();

    lblPassed.Text = queryPassedControls.Where(t => t.START_DATE_TIME >= DateStart && 
                                t.START_DATE_TIME <= DateEnd && 
                                t.UUT_STATUS == "Passed").Count().ToString();
}

【讨论】：