Why query doesn't work if the value is blank - asp.net

Question

I have a query that executes in my C# code:
protected void btnSearch_Click(object sender, EventArgs e) {
Conn = new SqlConnection(cString);
Conn.Open();
theGender = slcGender.SelectedItem.Text;
if (slcLocation.SelectedItem.Value == "") {
locVal = slcLocation.SelectedItem.Value;
}
if (slcLocation.SelectedItem.Value != "") {
locVal = slcLocation.SelectedItem.Text;
}
if (slcSpecialty.SelectedItem.Value == "") {
speVal = slcSpecialty.SelectedItem.Value;
}
if (slcSpecialty.SelectedItem.Value != "") {
speVal = slcSpecialty.SelectedItem.Text;
}
if (slcGender.SelectedItem.Value == "") {
genVal = slcGender.SelectedItem.Value;
}
if (slcGender.SelectedItem.Value != "") {
genVal = theGender.Substring(0, 1);
}
sqlCode =
"DECLARE #strLocation varchar(200)
SET #strLocation = '" + locVal + "'
DECLARE #strSpecialty varchar(200)
SET #strSpecialty = '" + speVal + "'
DECLARE #strGender varchar(200)
SET #strGender = '" + genVal + "'
SELECT
[content_title] AS [Physician Name]
, CAST([content_html] AS XML).value('(root/Physicians/picture/img/#src)[1]','varchar(255)') AS [Image]
, dbo.usp_ClearHTMLTags(CONVERT(nvarchar(600), CAST([content_html] AS XML).query('root/Physicians/gender'))) AS [Gender]
, CAST([content_html] AS XML).query('/root/Physicians/OfficeLocations/office1/a') AS [Office1]
, CAST([content_html] AS XML).query('/root/Physicians/OfficeLocations/office2/a') AS [Office2]
, CAST([content_html] AS XML).query('/root/Physicians/OfficeLocations/office3/a') AS [Office3]
, CAST([content_html] AS XML).query('/root/Physicians/OfficeLocations/office4/a') AS [Office4]
, dbo.usp_ClearHTMLTags(CONVERT(nvarchar(600), CAST([content_html] AS XML).query('/root/Physicians/phone1'))) AS [Phone #]
FROM
[database].[dbo].[content]
WHERE
[folder_id] = '188'
AND
(content_html LIKE '%<gender>'+ #strGender+'</gender>%')
AND
(content_html LIKE '%'+#strSpecialty+'%')
AND
(content_html LIKE '%'+#strLocation+'%')
ORDER BY
[content_title]";
/* EXECUTE AND DISPLAY THE DATA IN THE ASP PAGE */
using(SqlCommand command = new SqlCommand(sqlCode, Conn)) {
command.CommandType = CommandType.Text;
using (SqlDataReader reader = command.ExecuteReader()) {
if (reader.HasRows) {
rptContent.DataSource = reader;
rptContent.DataBind();
}
else {
dlo.InnerHtml = "NO RESULT";
}
}
}
}
The declaration are for three separate dropdownlist in my ASP.net page. I am having an issue where If I execute the query with the above code, no result will show up, although there should be about 5 results.
The three dropdownboxes are as follow:
The All Locations, All Specialties, Any Gender has value of "" which should makes the following code search for ALL, if I understand correctly?
(content_html LIKE '%<gender>'+ #strGender+'</gender>%')
AND
(content_html LIKE '%'+#strSpecialty+'%')
AND
(content_html LIKE '%'+#strLocation+'%')
The only time it works if I fill in the gender and/or location along with the specialty, before the query gives me anything back.
How do I resolve it?

Answer 1

If gender is missing, it is probably missing, so there are no <gender> delimiters. Perhaps this will fix the problem:
(#strGender = '' or (content_html LIKE '%<gender>'+ #strGender+'</gender>%')) . . .