如何使用C＃varchar数据类型？ [英] How to use the varchar data type in c#?

问题描述

我有这样的一段代码，我想使它VARCHAR不串。什么是适当的语法做，在C＃

 字符串emri =行[诺姆]的ToString（）。 
  

我有一个查询，我必须跑，我在使用它emri并与一列比较表，其中我在mysql中创建。在MySQL中列类型为varchar（20）。当我执行我的代码它给出了一个错误在我的查询，我猜也许是因为这个原因。

 我有这个疑问
查询字符串=IF NOT EXISTS（SELECT * FROM clienti WHERE CodCliente =+编号+和诺姆='+ emri +'AND RagioneSociale ='+ ragSoc +'AND PartitaIVA ='+皮瓦+'）INSERT INTO clienti VALUES（+编号+，'+ emri +，+ ragSoc +，+皮瓦+'），否则UPDATE clienti SET（+编号+ '+ emri +，+ ragSoc +，+皮瓦+'）; 
  

和它给了我这个问题。

 你在你的SQL语法错误;检查对应于你的MySQL服务器版本使用附近的正确语法手册IF NOT EXISTS（SELECT * FROM clienti WHERE CodCliente = 1 AND NomeCliente ='乔'在行1 
  

解决方案

有没有 VARCHAR 键入C＃。

A VARCHAR 几乎是一个字符串（可变长度的SQL，很明显），所以你有什么是好的

I have this piece of code and I want to make it varchar not string. What is the appropriate syntax to do that in c#

 string emri = row["Nome"].ToString();

I have a query that I have to run and I use emri in it and compare it with a column in table which I have created in mysql. the column in mysql is of type varchar(20). When I execute my code it gives an error in my query and I was guessing maybe it was for this reason

I have this query 
string query = "IF NOT EXISTS(SELECT * FROM clienti WHERE CodCliente=   " + id + "  AND Nome = '" + emri + "' AND RagioneSociale=' " + ragSoc + " ' AND PartitaIVA=' " + piva + " ') INSERT INTO clienti VALUES(" + id + " ,' " + emri + " ',' " + ragSoc + " ',' " + piva + " ') else UPDATE clienti SET( " + id + " ,' " + emri + " ',' " + ragSoc + " ',' " + piva + " ')";

and it gives me this problem

You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'IF NOT EXISTS(SELECT * FROM clienti WHERE CodCliente=   1  AND NomeCliente = 'Jo' at line 1

解决方案

There is no varchar type in C#.

A varchar is pretty much a string (of variable length in SQL, obviously), so what you have is fine.

这篇关于如何使用C＃varchar数据类型？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！