要清除Windows应用程序中'='附近的错误语法错误 [英] To clear a error incorrect syntax near '=' in windows application

问题描述

在给定编码中，由于在="="附近语法错误，我有错误.请更正该错误

i have error as incorrect syntax near ''='' , in given coding. please correct that error

private void listBox1_SelectedIndexChanged(object sender, EventArgs e)
       {

           cmd = new SqlCommand(" select * from imagedemo where='"+listBox1.SelectedItem.ToString()+"'", con);
           con.Open();
           SqlDataReader dr;
           try
           {
               dr = cmd.ExecuteReader();
               if (dr.Read())
               {
                   byte[] picture = (byte[])dr["imgimage"];
                   ms = new MemoryStream(picture);
                   ms.Seek(0, SeekOrigin.Begin);
                   pictureBox1.Image = Image.FromStream(ms);

               }

           }
           catch (Exception ex)
           {
               MessageBox.Show(ex.Message);
           }
           finally
           {
               con.Close();
           }
       }

推荐答案

查询select * from imagedemo where=''"+listBox1.SelectedItem.ToString()+"''"存在问题.
您尚未提供列名.

尝试直接在SQL后端编辑器中运行此查询，以查看语法是否正确.

There is an issue with the query select * from imagedemo where=''"+listBox1.SelectedItem.ToString()+"''".
You have not provided the column name.

Try running this query in the SQL backend editor directly to see if the syntax is all correct.

您的SQL查询未声明您要查询的字段.而不是 WHERE = ，您应该有WHERE yourField =(其中，您的字段应替换您要查询的字段的名称.您还应该考虑使用参数化查询而不是字符串连接，因此我将这样编写查询: :-

Your SQL query does not state the field that you are querying against. Instead of WHERE = , you should have WHERE yourField = (where yourField should be substituted for the name af the field you wish to query against. You should also consider using parameterised queries instead of string concatenation, so I would write the query like this:-

SELECT field1, field2, field3 FROM myTable WHERE field4 = @field4Parameter;<br />
mycommand.Parameters.AddWithValue("@field4Parameter", myParameter)

注意，我为查询中的所有字段命名，而不是使用*符号.这样，当我检索结果时，它们总是以相同的顺序返回.

希望对您有帮助

Notice i named all my fields in the query instead of using the * symbol. That way when I retrieve the results they always come back in the same order.

Hope that helps

您在where子句中缺少参数，必须在where和before之后指定字段名称=

You are missing parameter in where clause,must specify field name after where and before =

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