jdbc.SQLServerException: 必须声明标量变量 "@P0where"异常原因及其解决办法

异常描述：

一个删除语句的功能按钮用Servlet+JDBC实现，点击按钮后报错：

com.microsoft.sqlserver.jdbc.SQLServerException: 必须声明标量变量 "@P0where"

原因：sql语句换行后，SQL语句换行时，把单词间的空格丢了。

解决办法：补上，丢失的空格，保持SQL的正确性。注：SQL语句换行后仍需保留单行时候的单词之间空格。

纠正之前代码：

String sql="update umdata set idumfolder=?"
	+"where idumfolder=? and not id  in"  
	+"(select max(id) from  umdata where idumfolder=? group by  sto  )";

String sql="delete from umdata"
        +"where idumfolder=? and not id  in"  
        +"(select max(id) from  umdata where idumfolder=? group by  sto  )";

 

 以下是纠正后的代码： 

public class EmployeeDAOImpl implements EmployeeDAO{

//20140129重复记录移至垃圾箱
	public void moveAllRepeatToTrash(Employee e) throws Exception {
		Connection conn = DbUtil.getConnection();
		String sql="update umdata set idumfolder=? "
					+"where idumfolder=? and not id  in "  
					+"(select max(id) from  umdata where idumfolder=? group by  sto  )";

		PreparedStatement prep = conn.prepareStatement(sql);

		prep.setString(1, "trash");	
		prep.setString(2, "out");	
		prep.setString(3, "out");			
		prep.executeUpdate();
		DbUtil.close();
	}
	//20140129彻底删除重复记录	
	public void deleteAllRepeat(Employee e) throws Exception {
		Connection conn = DbUtil.getConnection();
		String sql="delete from umdata "
			+"where idumfolder=? and not id  in "  
			+"(select max(id) from  umdata where idumfolder=? group by  sto  )";
		
		PreparedStatement prep = conn.prepareStatement(sql);
		prep.setString(1, "out");	
		prep.setString(2, "out");		
		prep.executeUpdate();
		DbUtil.close();
	}