Assignment error is thrown in the query

I have a query like this....

selectLeaveDetails = 
   "SELECT  UL.[PK_ID],UD.FIRST_NAME + ' ' + UD.LAST_NAME AS REQUESTBY," +
   "UL.[DATE_FROM] AS FROMDATE,UL.[DATE_TO] AS TODATE," 开发者_运维知识库+
   "UL.LEAVE_REQUEST_ON AS REQUESTON," +
   "REPLACE(UL.LEAVE_REQUEST_NOTES, '\n', '<br />') AS REQUESTNOTES," +
   "STATUS=CASE " +
   " WHEN UL.[LEAVE_STATUS] = '1' THEN 'ACTIVE' " +
   " WHEN UL.[LEAVE_STATUS] = '-1' THEN 'CANCELLED' " +
   " WHEN UL.[LEAVE_STATUS] = '2' THEN 'REPLACED' END," +
   "UL.LEAVE_RESPONSE_ON AS RESPONSEON," +
   "ULL.FIRST_NAME + ' ' + ULL.LAST_NAME AS RESPONSEBY," +
   "UL.[LEAVE_RESPONSE_NOTES] AS RESPONSENOTES,UL.FK_LEAVE_REQUESTER " +
   "FROM (M_USER_LEAVES UL " +
   "INNER JOIN M_LEADERLED MLL ON MLL.LED_ID = MUD.PK_ID WHERE MLL.LEADER_ID = '" + Session["UserID"].ToString() ****" +****
   "LEFT JOIN M_USER_DETAILS UD ON UD.PK_ID = UL.FK_LEAVE_REQUESTER) " +
   "LEFT JOIN M_USER_DETAILS ULL ON ULL.PK_ID = UL.FK_LEAVE_RESPONSE_BY " +
   " WHERE UL.DATE_FROM BETWEEN '01/01/" + cmbYearList.SelectedItem.Text + "' AND '12/31/" + cmbYearList.SelectedItem.Text + "'" +
   " AND UD.ACTIVE=1";

In the cmbYearList.SelectedItem.Text + "' AND '12/31/" + cmbYearList.SelectedItem.Text + "'" query...only assignment,increment,decrement error is thrown

Can anyone help me?

Your FROM clause is somehow pretty mangled up:

FROM (M_USER_LEAVES UL 
       INNER JOIN M_LEADERLED MLL ON MLL.LED_ID = MUD.PK_ID 
       WHERE MLL.LEADER_ID = 'XXXX" 
       LEFT JOIN M_USER_DETAILS UD ON UD.PK_ID = UL.FK_LEAVE_REQUESTER) 

You have an INNER JOIN, then a WHERE clause, followed by a LEFT JOIN .... this seems pretty odd..... what exactly are you trying to do here?? Why do you need to put this into a subquery - can't you just INNER JOIN and LEFT JOIN those tables into a single statement and define the necessary WHERE constraints?

Also, your WHERE clause in here gets an opening single quote and a closing double quote - that won't work ......

WHERE MLL.LEADER_ID = 'XXXX" 
                     ***   ***

You need to get your SQL query working in SQL Server Management Studio first - then transfer it into your C# code.