记录从sql server中删除 [英] record deleting from sql server

问题描述

SqlConnection con=new SqlConnection ("connectionstring");
        con.Open ();
        SqlCommand cmd = new SqlCommand("select count(*) from tableName where cid=1233", con);
        int i = 0;
        i=(int)cmd.ExecuteScalar();
        if (i > 0)
        {
            //record is available
            SqlCommand deleteCmd = new SqlCommand("delete tablename where cid=1233", con);
            int res = 0;
            res=deleteCmd.ExecuteNonQuery();
            if (res > 0)
            {
                //deleted successfully
            }
            else
            {
                //failed to delete
            }
        }
        else
        {
            //there is no record
        }

这是问题所在
i =(int)cmd.ExecuteScalar();

每次我得到我> 0 false

here is the problem
i=(int)cmd.ExecuteScalar();

every time me getting i > 0 false

推荐答案

您需要在以下行中进行修复，

SqlConnection con=new SqlConnection ("connectionstring");

SqlConnection 需要一个连接字符串，当您传递"connectionstring"时，该字符串不是SqlConnection的有效连接字符串.

供您参考，

sqlconnection [ ^ ]

连接字符串/ [ ^ ]

sqlconnection-connection-string.aspx [ ^ ]

希望对您有所帮助:)

You would need to fix in the below line,

SqlConnection con=new SqlConnection ("connectionstring");

SqlConnection needs a connection string where as you are passing "connectionstring" which is not a valid connection string for SqlConnection.

For your ref,

sqlconnection[^]

connectionstrings/[^]

sqlconnection-connection-string.aspx[^]

Hope it helps :)

这意味着查询

This means the query

select count(*) from tableName where cid=1233

总是返回0.检查数据库中是否有与此条件相关的记录.

always returns 0. Check if there are any records in database with this condition.

在条件必须且应满足的查询中，oly您将得到i = 1，只需给出有效的连接字符串和有效的查询

Hi,
in query where condition must and should satisfy then oly u will get i=1 ,just give valid connectionstring and valid query

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