了解Sql查询 [英] Understanding Sql Query

问题描述

在此查询中从临时表''DTLocal''数据显示文本框。在这里，我不明白为什么？使用标记。请帮帮我

In this query from temp table ''DTLocal'' data shown textbox. Here I cann''t understand why ? marks is used. please help me

txtTruckReceiptDate.Text = (DTLocal.Rows[0]["TruckReceiptDate"].ToString() == "" ? "" : DateTime.Parse(DTLocal.Rows[0]["TruckReceiptDate"].ToString()).ToString("dd-MMM-yyyy"));

txtDocHODate.Text = (DTLocal.Rows[0]["DOCHODate"].ToString() == "" ? "" : DateTime.Parse(DTLocal.Rows[0]["DOCHODate"].ToString()).ToString("dd-MMM-yyyy"));

推荐答案

它基本上是一个三元运算符。问号与冒号相结合。

这样工作：

Its basically a ternary operator. The question mark combined with the colon sign.
Works like this:

string name = ABooleanExpression ? "Jack" : "Jill";

如果布尔值为true，则将分配变量名称作为杰克，如果没有，那么变量名将是吉尔。



在你的代码中参考这个理解，你就会得到它。

希望它有帮助。



-ANurag

If the boolean exp is true then the variable name will be assigned as Jack, if not then the variable name will be Jill.

Refer this understanding in your code and you will get it.
Hope it helps.

-ANurag

这是三元运算符 [ ^ ]。

It is a Ternary Operator[^].

引用：

条件？ first_expression：second_expression;

condition ? first_expression : second_expression;

For first line of code...
condition - DTLocal.Rows[0]["TruckReceiptDate"].ToString() == ""
first_expression - ""
second_expression - DateTime.Parse(DTLocal.Rows[0]["TruckReceiptDate"].ToString()).ToString("dd-MMM-yyyy"))

如果条件满足，将执行 first_expression ，否则将执行 second_expression 。



所以，对于第一行...

If condition is satisfied the first_expression will be executed, otherwise second_expression will be executed.

So, for first line...

txtTruckReceiptDate.Text = (DTLocal.Rows[0]["TruckReceiptDate"].ToString() == "" ? "" : DateTime.Parse(DTLocal.Rows[0]["TruckReceiptDate"].ToString()).ToString("dd-MMM-yyyy"));

这里检查 DTLocal.Rows [0] [TruckReceiptDate]的值.ToString（ ）。

和

- > 如果值为，则会将分配给 txtTruckReceiptDate.Text ，

- > 否则它指定 DateTime.Parse（DTLocal.Rows [0] [TruckReceiptDate]。ToString（））。ToString（dd-MMM-yyyy））到 txtTruckReceiptDate.Text

Here it checks the value of DTLocal.Rows[0]["TruckReceiptDate"].ToString().
And
-> if the value is "", it assigns "" to txtTruckReceiptDate.Text,
-> otherwise it assigns DateTime.Parse(DTLocal.Rows[0]["TruckReceiptDate"].ToString()).ToString("dd-MMM-yyyy")) to txtTruckReceiptDate.Text

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