Interbase SQL statement not working
I am trying to write a SQL Statement for Interbase.
Whats wrong with this SQL?
md_master (trm) = Master Table cd_Med (cdt) = Detail table
SELECT trm.seq_no, trm.recipient_id, trm.payee_fullname, trm.payee_address1, trm.payee_address2, trm.payee_address3, trm.payee_address_city, trm.payee_address_state, trm.recip_zip, trm.recip_zip_4, trm.recip_zip_4_2, trm.check_no, trm.check_date, trm.check_amount,
cdt.com开发者_如何学运维_ss_source_sys, cdt.cd_pay_date, cdt.com_set_amount,
bnk.name, bnk.address, bnk.transit_routing,
act.acct_no
FROM md_master trm, cd_med cdt, accounts act, banks bnk
join cd_med on cdt.master_id = trm.id
join accounts on act.acct_id = trm.account_tag
join banks on bnk.bank_id = act.bank_id
ORDER BY cdt.master_id
I don't get an error, the computer just keeps crunching away and hangs.
I don't know about Interbase specifically, but that FROM clause seems a little strange (perhaps just some syntax I'm not familiar with though). Does this help?
...
FROM md_master trm
join cd_med cdt on cdt.master_id = trm.id
join accounts act on act.acct_id = trm.account_tag
join banks bnk on bnk.bank_id = act.bank_id
By the way, you have no WHERE clause so if any of these tables is large, I wouldn't be overly surprised that it takes a long time to run.
You have been bitten by an anti-pattern called implicit join syntax
SELECT * FROM table_with_a_1000rows, othertable_with_a_1000rows
Will do a cross-join on both tables selecting 1 million rows in the output.
You are doing:
FROM md_master trm, cd_med cdt, accounts act, banks bnk
A cross join on 4 tables (combined with normal joins afterwards), which could easily generate many billions of rows.
No wonder interbase hangs; it is working until the end of time to generate more rows then there are atoms in the universe.
The solution
Never use ,
after the FROM clause, that is an implicit join and it is evil.
Only use explicit joins, like so:
SELECT
trm.seq_no, trm.recipient_id, trm.payee_fullname, trm.payee_address1
, trm.payee_address2, trm.payee_address3, trm.payee_address_city
, trm.payee_address_state, trm.recip_zip, trm.recip_zip_4, trm.recip_zip_4_2
, trm.check_no, trm.check_date, trm.check_amount
, cdt.com_ss_source_sys, cdt.cd_pay_date, cdt.com_set_amount
, bnk.name, bnk.address, bnk.transit_routing
, act.acct_no
FROM md_master trm
join cd_med on cdt.master_id = trm.id
join accounts on act.acct_id = trm.account_tag
join banks on bnk.bank_id = act.bank_id
ORDER BY cdt.master_id
The error lie in the from clause. You are using half with comma separated tables without a relation in where clause and half with joins.
Just use joins and all should work fine
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