@SuppressWarnings("unchecked")
    public <N extends Object> List<N> findOneColumn(String sql, List<?> params, final int mapperColumnIndex) {

        if (sql == null) {
            recordLog(" param sql is null!");
        }

        // 查询
        return findBySQL(sql, params, new RowMapper<N>() {
            public N mapRow(ResultSet rs, int count) throws SQLException {
                return (N) (rs.getObject(mapperColumnIndex));
            }
        });
    }
@ SuppressWarnings ( "unchecked" ) public < N extends Object > List < N > findOneColumn ( String sql , List < ? > params , final int mapperColumnIndex ) { if ( sql == null ) { recordLog ( " param sql is null!" ) ; } return findBySQL ( sql , params , new RowMapper < N > ( ) { public N mapRow ( ResultSet rs , int count ) throws SQLException { return ( N ) ( rs . getObject ( mapperColumnIndex ) ) ; } } ) ; }
查询某一列的值

@param sql
@param params
@param mapperColumnIndex 要返回的哪一列的值，由1开始。

@return