Incorrect syntax near keyword 'd1' - asp.net

Question

The SQL query works in SQL Server Management Studio. But, in Visual studio it gives an error
Incorrect syntax near D1
Code:
private void GetDataByID(string _id)
{
string connectionString = ConfigurationManager.ConnectionStrings["DatabaseConnectionString"].ConnectionString;
using (SqlConnection connection = new SqlConnection(connectionString))
{
string sqlCommand = "SELECT d1.*, d2.* FROM KFM.dbo.ToolBoxDocContent as d1, KFM.dbo.ToolBoxDocument as d2" +
"where d1.DocumentId = d2.DocumentId and = d2.DocumentId =" + _id;
SqlCommand cmd = new SqlCommand(sqlCommand, connection);
SqlDataReader MyReader;
try
{
connection.Open();
MyReader = cmd.ExecuteReader();
while (MyReader.Read())
{
string sDueWeek = MyReader["DueWeek"].ToString();
string sTitle = MyReader["DocumentTitle"].ToString();
//string sEnglishBodyContent = MyReader["DocumentBody"].ToString();
//string sFrenchBodyContent = MyReader["DocumentBody"].ToString();
txb_Week.Text = sDueWeek;
txb_Title.Text = sTitle;
}
}
catch (Exception ex)
{
Response.Write(ex.Message);
}
}
}

Answer 1

Change the query as shown below
"SELECT d1.*, d2.* FROM KFM.dbo.ToolBoxDocContent as d1, KFM.dbo.ToolBoxDocument as d2
where d1.DocumentId = d2.DocumentId and d2.DocumentId ='" + _id + "'";

Answer 2

In your query, you also have entered = sign after and.
Try this code
string sqlCommand = "SELECT d1.*, d2.* FROM KFM.dbo.ToolBoxDocContent d1 inner join KFM.dbo.ToolBoxDocument as d2 on d1.DocumentId = d2.DocumentId " + " where d2.DocumentId = " + _id;
Also it's better to write store procedure instead and call from your c# code.

Answer 3

private void GetDataByID(string _id)
{
string connectionString = ConfigurationManager.ConnectionStrings["DatabaseConnectionString"].ConnectionString;
string sqlCommand = "SELECT d1.*, d2.* "
+ " FROM KFM.dbo.ToolBoxDocContent as d1"
+ " INNER JOIN KFM.dbo.ToolBoxDocument as d2 ON d1.DocumentId = d2.DocumentId"
+ " WHERE d2.DocumentId = #ID";
using (SqlConnection connection = new SqlConnection(connectionString))
using (SqlCommand cmd = new SqlCommand(sqlCommand, connection))
{
cmd.Parameter.Add("#ID", SqlDbType.Int).Value = int.Parse(_id);
try
{
connection.Open();
using (SqlDataReader MyReader = cmd.ExecuteReader()_
{
while (MyReader.Read())
{
string sDueWeek = MyReader["DueWeek"].ToString();
string sTitle = MyReader["DocumentTitle"].ToString();
//string sEnglishBodyContent = MyReader["DocumentBody"].ToString();
//string sFrenchBodyContent = MyReader["DocumentBody"].ToString();
txb_Week.Text = sDueWeek;
txb_Title.Text = sTitle;
}
}
}
catch (Exception ex)
{
Response.Write(ex.Message);
}
}
}

Answer 4

One thing I have noticed in your query is that
space is not provided properly before two joins using '+'. Use space before where
incorrect syntax at where clause. remove extra '=' after and at and = d2.DocumentId = " + _id
Your final query will look like as mentioned below:
string sqlCommand = "SELECT d1.*, d2.* FROM KFM.dbo.ToolBoxDocContent as d1, KFM.dbo.ToolBoxDocument as d2" +
" where d1.DocumentId = d2.DocumentId and d2.DocumentId =" + _id;
Update:
string sqlCommand = "SELECT d1.*, d2.* FROM KFM.dbo.ToolBoxDocContent as d1, KFM.dbo.ToolBoxDocument as d2" +
" where d1.DocumentId = d2.DocumentId and d2.DocumentId = '" + _id + "'";