执行sql语句的问题！求救！！！

Question

需要执行3条sql语句，但是除了第一条执行成功外，第二条yjsl我想+1，结果确是成了+2，第三条语句更强，没有执行。
将三个语句在查询管理器中执行后，没有任何问题，哪位高手知道是怎么回事？             
                string sqlStr1,sqlStr2,sqlStr3;
                sqlStr1 = "update TBL_BookInfoMX set state='1',ReaderID='" + this.ReaderID + "',JCCS=JCCS+1 WHERE BookID='" + BookID + "'";
                sqlStr2 = "update TBL_ReaderInfo set yjsl=yjsl+1 where ReaderID='" + this.ReaderID + "'";
                sqlStr3 = "INSERT INTO TBL_BookBorrow VALUES ('"+this.ReaderID+"','"+BookID+"',Getdate(),null,0)";
                DataBase DB = new DataBase();                SqlConnection conn = DB.getDbConnection();
               
                try
                {
                    conn.Open();                    SqlCommand cmd1 = new SqlCommand(sqlStr1, conn);                    cmd1.ExecuteNonQuery();                    //将TBL_ReaderInfo中的YJSL+1                    SqlCommand cmd2 = new SqlCommand(sqlStr2, conn);                    cmd2.ExecuteNonQuery();                    //将记录插入TBL_BookBorrow中                      SqlCommand cmd3 = new SqlCommand(sqlStr2, conn);                    cmd3.ExecuteNonQuery();                }
                finally
                {
                    conn.Close();
                }
                return true;

Answer 1

 SqlCommand cmd2 = new SqlCommand(sqlStr2, conn);                    cmd2.ExecuteNonQuery();                    //将记录插入TBL_BookBorrow中                      SqlCommand cmd3 = new SqlCommand(sqlStr2, conn);2个sqlStr2