使用 GROUP BY 分组查询

    SELECT
    sum( m.proj_amount ) AS planAmount,
    sum( c.construct_cost ) AS actualAmount,
    YEAR ( m.plan_start_time ) AS YEAR,
    MONTH ( m.plan_start_time ) AS MONTH
    FROM
    tb_maintain_plan AS m
    LEFT JOIN tb_construct_manage AS c ON m.proj_name = c.proj_name
    WHERE
    m.plan_period = ‘月度’ and m.road_segment_name = ‘滨江高速/金水段’
    GROUP BY
    YEAR ( m.plan_start_time ),
    MONTH ( m.plan_start_time )