问题
I have a problem, that I can't solve. I'm using SQL Server 2005, C# CLR for using outer dll. The problem is at length of parameter. I need to use as function parameter type varchar(max). If at C# code I use string, SqlSring, I can't use T-SQL type varchar(max), just varchar(4000) of nvarchar(4000). I need to say, that can be situations, when I need to use more then 4000 symbols, so I need know, what C# type I need to use for varchar(max).
I have read a lot of articles, and several of them say, that for this I can use SqlChars. But! I have manipulations with strings. How can I have actions with string or SqlString and then convert to SqlChars? (It is possible SqlChars.ToString() or SqlChars.ToSqlString()).
I didn't find any C# code for this.
回答1:
What you need to do is add SqlFacet(MaxSize = -1) attribute to parameter:
[return: SqlFacet(MaxSize = -1)]
[Microsoft.SqlServer.Server.SqlFunction(IsDeterministic = true)]
public static SqlString YourSqlFunction([SqlFacet(MaxSize = -1)]SqlString sourceSS)
{ return new }
回答2:
I found the answer. Not just only me asked about this question. I have to read posts more attentively...
Can read here http://social.msdn.microsoft.com/Forums/is/sqlnetfx/thread/391ebb98-e1b5-47fc-a72d-9f1e39829e3a The problem of CLR compatibility solves not very difficult.
All time I wanted use varchar(max) and tried to use C# types string, SqlString, SqlChars. Need to use T-SQL nvarchar(max), and you can use any of C# types string, SqlString, SqlChars!
Of course nvarchar taking up more space than varchar at two times.
回答3:
Try using length -1. Something like this:
cmd.Parameters.Add("@param", SqlDbType.VarChar, -1).Value = "hdfiophdopigherog";
来源：https://stackoverflow.com/questions/7580123/t-sql-varcharmax-vs-clr-string-sqlstring-sqlchars