Caml Query returns all the values from sharepoint online

Question

i am using a caml query to check if a specific value exist in a sharepoint list. but it ends up returnning all the values instead of one.

          while (reader.Read())
                {
                 //   MessageBox.Show(reader[5].ToString());
                    CamlQuery camlQuery = new CamlQuery();
                    camlQuery.ViewXml =
                        @"<Query>
<Where>
  <Eq>
    <FieldRef Name='Email_x0020_Address' />
    <Value Type='Text'>[email protected]</Value> </Eq></Where></Query>";
                    ListItemCollection listItems = myList.GetItems(camlQuery);
                    ctx.Load(
                         listItems
                         );
                    ctx.ExecuteQuery();

                    if (listItems.Count != 0)
                    {
                        MessageBox.Show("Item Exists");
                        foreach (ListItem listItem in listItems.ToList())
                        {
                            MessageBox.Show(listItem["Email_x0020_Address"].ToString());
                        }
                    }
                    else
                    {
                        MessageBox.Show("Item Does not exists");
                    }

Answer 1

You are missing View tag.

Please try to put your query inside View tag. It will retrieve filtered data only.

<View>
    <Query>
        <Where>
            ...
            ...
            ...
        </Where>
    </Query>
</View>

Answer 2

Removing the Query keyword could work.

camlQuery.ViewXml = @"<Where><Eq><FieldRef Name='Email_x0020_Address' /<Value Type='Text'>[email protected]</Value></Eq></Where>";

Alternatively, you can try to first append all the items in the list to a List of ListItem and then do your query by using LINQ. It was suggested to me by someone in here and I find it easier, more structured and never fails in large data sets (unlike CAML Query which does not work with over 5000 items).