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Delete with join to multiple tables

开发者 https://www.devze.com 2023-02-04 12:33 出处:网络
Code: create table coltype (coltype varchar(5)); insert into coltype values (\'typ1\'); create table colsubtype (coltype varchar(5), colsubtype varchar(5));

Code:

create table coltype (coltype varchar(5));

insert into coltype values ('typ1');

create table colsubtype (coltype varchar(5), colsubtype varchar(5));

insert into colsubtype values ('typ2', 'st1');
insert into colsubtype values ('typ2', 'st2');

create table table1 (col1 varchar(5), coltype varchar(5), colsubtype varchar(5));

insert into table1 values ('val1','typ1', 'st1');
insert into table1 values ('val2','typ1', 'st2');
insert into table1 values ('val3','typ1', 'st3');
insert into table1 values ('val4','typ2', 'st1');
insert into table1 values ('val5','typ2', 'st2');
insert into table1 values ('val6','typ2', 'st3');
insert into table1 values ('val7','typ3', 'st1');
insert into table1 values ('val8','typ3', 'st2');
insert into table1 values ('val9','typ3', 'st3');

commit;

Basically, I want to delete all records where the coltype and colsubtype is not mentioned in the coltype and colsubtype tables.

How do I do that. The below is path I was thinking of taking but it does not work - and - it does not seem like a good design.

delete from table1 
where coltype != (select coltype from coltype) 
    OR not (coltype = cst.coltype and colsu开发者_运维技巧btype = cst.colsubtype 
from (select coltype,  colsubtype from colsubtype) cst)


Using NOT EXISTS:

delete from t1 
    from table1 t1
    where not exists (select null from coltype ct where ct.coltype = t1.coltype)
       or not exists (select null from colsubtype cst where cst.colsubtype = t1.colsubtype)

Using LEFT JOINs:

delete from t1 
    from table1 t1
        left join coltype ct
            on t1.coltype = ct.coltype
        left join colsubtype cst
            on t1.colsubtype = cst.colsubtype
    where ct.coltype is null 
       or cst.colsubtype is null


Give this a try

delete from table1
where not exists
        (
        select *
        from coltype
        where table1.coltype = coltype.coltype
        )
    and not exists
        (
        select *
        from colsubtype
        where table1.coltype = colsubtype.coltype
            and table1.colsubtype = colsubtype.colsubtype
        ) 


your code will need to leverage the "not exists" operator pretty heavily

delete from table1
where not exists
(
    select 1 from colType ct where ct.colType = table1.colType
)
and not exists
(
    select 1 from colsubtype cst where cst .colSubType = table1.colSubType
)


DELETE FROM table1
WHERE coltype IN 
(SELECT coltype 
 FROM table1 
 WHERE coltype NOT IN (SELECT coltype FROM coltype))
OR colsubtype IN 
(SELECT colsubtype 
 FROM table1 
 WHERE colsubtype NOT IN (SELECT colsubtype FROM colsubtype))
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