Question

I have joined two tables using inner join. Here primary key of table TPREG is co_id and pol_id

 SELECT (SELECT etbl_desc_txt
       FROM uding604.tedit e
       WHERE etbl_typ_id = 'PITCD'
       AND   co_id = 'CP'
       AND   etbl_valu_id = p.pol_ind_typ_cd) pol_ind_typ_cd,
       (SELECT etbl_desc_txt
        FROM uding604.tedit e
        WHERE etbl_typ_id = 'PAYT'
        AND   co_id = 'CP'
        AND   etbl_valu_id = p.POL_BILL_TYP_CD) POL_BILL_TYP_CD,
       POL_PAC_DRW_DY,
       (SELECT etbl_desc_txt
        FROM uding604.tedit e
        WHERE etbl_typ_id = 'PAYM'
        AND   co_id = 'CP'
        AND   etbl_valu_id = p.POL_BILL_MODE_CD) POL_BILL_MODE_CD,
       t.SOURCE_CD
FROM uding604.tpol p,
     uding604.TPREG t
WHERE p.co_id = t.co_id
AND   p.pol_id = t.pol_id
AND   p.co_id = 'CP'
AND   p.pol_id = '000000011'
AND   t.co_id = 'CP'
AND   t.pol_id = '000000011'

How to make this query more simple?

Please guide.

Answer 1

You can transform the subqueryes to joins:.

SELECT e1.etbl_desc_txt as pol_ind_typ_cd,
       e2.etbl_desc_txt as POL_BILL_TYP_CD,
       POL_PAC_DRW_DY,
       e3etbl_desc_txt as POL_BILL_MODE_CD,
       t.SOURCE_CD
FROM uding604.tpol p,
     uding604.TPREG t,
     uding604.tedit e1,
     uding604.tedit e2,
     uding604.tedit e3
WHERE p.co_id = t.co_id
AND   p.pol_id = t.pol_id
AND   p.co_id = 'CP'
AND   p.pol_id = '000000011'
AND   t.co_id = 'CP'
AND   t.pol_id = '000000011'
AND   e1.etbl_typ_id = 'PITCD'
AND   e1.co_id = 'CP'
AND   e1.etbl_valu_id = p.pol_ind_typ_cd
AND   e2.etbl_typ_id = 'PAYT'
AND   e2.co_id = 'CP'
AND   e2.etbl_valu_id = p.POL_BILL_TYP_CD
AND   e3.etbl_typ_id = 'PAYM'
AND   e3.co_id = 'CP'
AND   e3.etbl_valu_id = p.POL_BILL_MODE_CD

The query is clearer on select clause but is fuzzy at Where clause.

What we can do is to move on ANSI JOIN syntax:

SELECT e1.etbl_desc_txt as pol_ind_typ_cd,
       e2.etbl_desc_txt as POL_BILL_TYP_CD,
       POL_PAC_DRW_DY,
       e3etbl_desc_txt as POL_BILL_MODE_CD,
       t.SOURCE_CD
FROM uding604.tpol p 
JOIN uding604.TPREG t on (p.co_id = t.co_id AND p.pol_id = t.pol_id)
JOIN uding604.tedit e1 on (e1.etbl_valu_id = p.pol_ind_typ_cd and e1.co_id = p.co_id)
JOIN uding604.tedit e2 on (e2.etbl_valu_id = p.POL_BILL_TYP_CD and e2.co_id = p.co_id)
JOIN uding604.tedit e3 on (e3.etbl_valu_id = p.POL_BILL_MODE_CD and e3.co_id = p.co_id)
WHERE p.co_id = 'CP'
AND   p.pol_id = '000000011'
AND   t.co_id = 'CP'
AND   t.pol_id = '000000011'
AND   e1.etbl_typ_id = 'PITCD'
AND   e2.etbl_typ_id = 'PAYT'
AND   e3.etbl_typ_id = 'PAYM'

Now is clearer what you want.

Note1. You may try to remove

AND   t.co_id = 'CP'
AND   t.pol_id = '000000011'

because is not logic necessarly.

Note2. You must test if these queryes return the same as your query.

Note3. You should allways use ANSI JOIN syntax, will help you when you not expect it.