System.Data.SyntaxErrorException: 'Syntax error: Missing operand after '=' operator.&-CodePudding

I'm trying to make a search bar that searches in the Access database table with multiple criteria . when I type in the search bar a number it will do the search just fine, but when I delete what's in the search bar it shows me this error: System.Data.SyntaxErrorException:

'Syntax error: Missing operand after '=' operator.'

And when I type a character it shows me this error:

'System.Data.EvaluateException: 'Cannot find column [a].'

note: the Chamber field is type number long integer .

here is the the search code:

 private void ResSearchtextBox_TextChanged(object sender, Eventers e)
 {
     Data View dv = dt.DefaultView;
     dv.RowFilter = "(Name LIKE'%"   ResSearch_textBox.Text   "%') OR (Surname LIKE'%"   ResSearch_textBox.Text   "%') OR (Chamber ="   ResSearch_textBox.Text   ")";            
     ResDGV.DataSource = dv;
 }

what I've tried

     private void ResSearchtextBox_TextChanged(object sender, EventArgs e)
     {
        DataView dv = dt.DefaultView;
        dv.RowFilter = "(Name LIKE'%"   ResSearch_textBox.Text   "%') OR (Surname LIKE'%"   ResSearch_textBox.Text   "%') OR (Chamber ='"   ResSearch_textBox.Text   "')";            
        ResDGV.DataSource = dv;
     }

CodePudding user response：

The issue you're seeing is because the RowFilter property expects a string in the format of an SQL WHERE clause, and you are trying to use it to filter based on the value in the ResSearch_textBox control. When the text box is empty, the RowFilter property is being set to "(Name LIKE'%%') OR (Surname LIKE'%%') OR (Chamber =)", which is causing the error you mentioned. When you type a character in the text box, the RowFilter property is being set to "(Name LIKE'%a%') OR (Surname LIKE'%a%') OR (Chamber ='a')", which is causing the second error you mentioned.

To fix these issues, you can add some logic to your code to handle the case where the text box is empty. One way to do this is to check the length of the text in the text box, and only apply the filter if the length is greater than 0. You can also use the TryParse method to try converting the text in the text box to a number, and only apply the Chamber = filter if the conversion is successful.

CodePudding user response：

If there is no value in ResSearch_textBox, the formatted row filter will be, in part, ...OR (Chamber =) in the first case,and ...OR (Chamber = ''), in the second. The first is invalid SQL, as the error indicates. The second might be a database error, because if the Chamber field is expected to be a number, ’’ can’t be converted to one. The solution depends on what you want to happen if there is no chamber filter. If you don’t want to do the query at all, you could add code to the handler to skip the query if there’s no value. You could also substitute a default value — 0, maybe? — instead of a blank.

CodePudding user response：

The error is pretty clear, then the value of the textbox is empty in that case it becomes something like (Name LIKE'%%') OR (Surname LIKE'%%') OR (Chamber =) and hence there is no value after = that is why you are seeing the Syntax error: Missing operand after '=' operator.' error.

your second error looks related to the datatype.

when you have only an a character in that case RowFilter is trying to compare with the string value but the Chamber datatype is different.

so you should add a check like before this code if (searchText == "" || add other checks here) { return; }