Question

I have this sql (below) written by a previous developer. How can I break it up into three or four parts and join it together again instead of this single big sql? Please advise. I’m really new to sql and no idea how to simplify it. Thanks. I’m using C# console application.

SELECT distinct
  department_name CTG_DEPARTMENT,
  chart_id SPC_CHART_ID,
  concat(process_id, concat('-', item_name)) MONITOR_ITEM,
  product_id CTG_PRODUCT, 
  graphtype SPC_GRAPH_TYPE,
  CASE WHEN viorules LIKE '%9%'  THEN 'OOS'
       WHEN viorules LIKE '%10%' THEN 'OOS'
       WHEN viorules IS NULL     THEN 'OK'
                                 ELSE 'OOC' END SPC_STATUS,
  process_stage,
  'L8B' fab_name 
FROM
(
  SELECT
    'ARRAY' process_stage,
     dept.item_name department_name,
     dept.chart_id,
     proc_id.item_name process_id,
     item.item_name,
     product.item_name product_id, 
     graphtype
  FROM 
  (
    SELECT
      item_name,
      chart_id
    FROM
      aryspch.c_ctg_filter f,
      aryspch.c_ctg_item i,
      aryspch.c_ctg_relate r
    WHERE
      GROUP_ID = 6 
      AND filter_name IN ('Department')
      AND f.filter_id = i.filter_id
      AND i.item_id = r.item_id
  ) dept
  ,
  (
    SELECT
      item_name,
      chart_id
    FROM
      aryspch.c_ctg_filter f,
      aryspch.c_ctg_item   i,
      aryspch.c_ctg_relate r
    WHERE
      GROUP_ID = 6
      AND filter_name IN ('Process_ID')    
      AND f.filter_id = i.filter_id
      AND i.item_id = r.item_id
  ) proc_id
  ,
  (
    SELECT
      item_name,
      chart_id
    FROM
      aryspch.c_ctg_filter f,
      aryspch.c_ctg_item   i,
      aryspch.c_ctg_relate r
    WHERE
      GROUP_ID = 6
      AND filter_name IN ('Item')
      AND f.filter_id = i.filter_id
      AND i.item_id = r.item_id
  ) item
  ,
  (
    SELECT
      item_name,
      chart_id
    FROM
      aryspch.c_ctg_filter f,
      aryspch.c_ctg_item   i,
      aryspch.c_ctg_relate r
    WHERE
      GROUP_ID = 6
      AND filter_name IN ('Product')
      AND f.filter_id = i.filter_id
      AND i.item_id = r.item_id
  ) product
  ,
  (
    SELECT DISTINCT
      chartid,
      graphtype
    FROM
      aryspch.spchis
    WHERE
      reporttime > SYSDATE - 2
  ) a
  WHERE
        dept.chart_id = proc_id.chart_id
    AND dept.chart_id = item.chart_id
    AND dept.chart_id = product.chart_id
    AND dept.chart_id = a.chartid
)
  spc
LEFT JOIN
(
  SELECT
    viorules,
    mtimestamp,
    chartid
  FROM
    aryspch.oochis
)
  oochis
    ON  spc.chart_id = oochis.chartid
    AND mtimestamp > SYSDATE - 2

Answer 1

One option is to use Common Table Expressions to define each sub-query, and then to join those named queries together.

WITH
  dept AS
(
  SELECT
    item_name,
    chart_id
  FROM
    aryspch.c_ctg_filter f,
    aryspch.c_ctg_item i,
    aryspch.c_ctg_relate r
  WHERE
    GROUP_ID = 6 
    AND filter_name IN ('Department')
    AND f.filter_id = i.filter_id
    AND i.item_id = r.item_id
)
,
  proc_id  AS
(
  SELECT
    item_name,
    chart_id
  FROM
    aryspch.c_ctg_filter f,
    aryspch.c_ctg_item   i,
    aryspch.c_ctg_relate r
  WHERE
    GROUP_ID = 6
    AND filter_name IN ('Process_ID')    
    AND f.filter_id = i.filter_id
    AND i.item_id = r.item_id
)
,
  item AS
(
  SELECT
    item_name,
    chart_id
  FROM
    aryspch.c_ctg_filter f,
    aryspch.c_ctg_item   i,
    aryspch.c_ctg_relate r
  WHERE
    GROUP_ID = 6
    AND filter_name IN ('Item')
    AND f.filter_id = i.filter_id
    AND i.item_id = r.item_id
)
,
  product AS
(
  SELECT
    item_name,
    chart_id
  FROM
    aryspch.c_ctg_filter f,
    aryspch.c_ctg_item   i,
    aryspch.c_ctg_relate r
  WHERE
    GROUP_ID = 6
    AND filter_name IN ('Product')
    AND f.filter_id = i.filter_id
    AND i.item_id = r.item_id
)
,
  a AS
(
  SELECT DISTINCT
    chartid,
    graphtype
  FROM
    aryspch.spchis
  WHERE
    reporttime > SYSDATE - 2
)
,
  spc AS
(
  SELECT
    'ARRAY' process_stage,
     dept.item_name department_name,
     dept.chart_id,
     proc_id.item_name process_id,
     item.item_name,
     product.item_name product_id, 
     graphtype
  FROM 
    dept,
    proc_id,
    item,
    product,
    a
  WHERE
        dept.chart_id = proc_id.chart_id
    AND dept.chart_id = item.chart_id
    AND dept.chart_id = product.chart_id
    AND dept.chart_id = a.chartid
)
,
  oochis AS
(
  SELECT
    viorules,
    mtimestamp,
    chartid
  FROM
    aryspch.oochis
)

SELECT distinct
  department_name CTG_DEPARTMENT,
  chart_id SPC_CHART_ID,
  concat(process_id, concat('-', item_name)) MONITOR_ITEM,
  product_id CTG_PRODUCT, 
  graphtype SPC_GRAPH_TYPE,
  CASE WHEN viorules LIKE '%9%'  THEN 'OOS'
       WHEN viorules LIKE '%10%' THEN 'OOS'
       WHEN viorules IS NULL     THEN 'OK'
                                 ELSE 'OOC' END SPC_STATUS,
  process_stage,
  'L8B' fab_name 
FROM
  spc
LEFT JOIN
  oochis
    ON  spc.chart_id = oochis.chartid
    AND mtimestamp > SYSDATE - 2