在StringBuilder中使用布尔表达式

Question

I'm using a string builder to build some SQL Scripts. I have a few Boolean Properties that I would like to test and then output different text based on true/false. I've you the C# syntax below when assigning a value to a variable, but it isn't working for this particular situation. Any ideas?

What I'm used to doing:

string someText = (dbInfo.IsIdentity) ? "First Option" : "Second Option";

Trying to duplicate the same thing inside a StringBuilder method, but this isn't working..

script.Append("sometext" + (dbInfo.IsIdentity) ? " IDENTITY(1,1)" : "");

Answer 1

添加括号：

script.Append("sometext" + ((dbInfo.IsIdentity) ? " IDENTITY(1,1)" : ""));

Answer 2

What about this?

script.Append( "sometext" );
script.Append( dbInfo.IsIdentity ? " IDENTITY(1,1)" : "" );

Answer 3

Other from stating that if you have a stringbuilder you should use it to concatenate strings.

That said, the code bellow should work.

script.Append("sometext");
script.Append(dbInfo.IsIdentity ? " IDENTITY(1,1)" : "");

In this particular case you could also do:

script.Append("sometext");
if(dbInfo.IsIdentity) script.Append(" IDENTITY(1,1)");

Answer 4

附加括号甚至更好使用AppendFormat

script.AppendFormat("sometext{0}", dbInfo.IsIdentity ? " IDENTITY(1,1)" : "");

Answer 5

Just a hunch but I think you need some more brackets:

script.Append("sometext" + ((dbInfo.IsIdentity) ? " IDENTITY(1,1)" : ""));

I would urge you to use a temporary variable for readability sake.

Answer 6

First, I would try wrapping the if/then/else in a set of parenthesis and see if that fixes the problem. It may be a problem with the order in which that expression is being evaluated.

Answer 7

一个快速的建议：如果要像这样生成SQL，与使用直接C＃相比，使用StringString之类的模板来生成SQL可能会更好。