Question

代码：

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;

基本上，我想删除coltype和colsubtype表中未提及coltype和colsubtype的所有记录。

我该怎么做。以下是我考虑采取的路径，但它不起作用 - 而且 - 它似乎不是一个好的设计。

delete from table1 
where coltype != (select coltype from coltype) 
    OR not (coltype = cst.coltype and colsubtype = cst.colsubtype 
from (select coltype,  colsubtype from colsubtype) cst)

Answer 1

使用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)

使用LEFT JOIN：

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

Answer 2

试一试

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
        )

Answer 3

您的代码需要非常重视“不存在”运算符

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
)

Answer 4

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))

删除并加入多个表

4 个答案: