How Oracle databases implement left and right outer-union

Create or replace view V_wtk_all as

Select a.ID, O.short as Finddeptname, u.realname as Findusername, f.name as Findway, O1.short as Problematdeptname,

Z.name as Szzz, A.yhnr, s.name as Sszy, k.name as kind, w.name as WHHG, A.zgcs, A.ZGFZR, A.plandate, A.finishdate,

U1.realname as JDR, u2.realname as FXR, A.yqzt, A.yqdate, A.WTKZT

From WTK A, organization O, organization O1, OPERATORS u,operators u1,operators U2, Kind K, Findway F, SPField S, Szzz Z, WHHG W

where A.finddeptid =o.id (+) and a.problematdeptid=o1.id (+) and a.finduserid=u.id (+) and a.jdr=u1.id (+) and (+) and a.fxr=u2.id (+ )

and A.kindid=k.id (+) and a.findwayid=f.id (+) and a.spfieldid=s.id (+) and A.szzid =z.id (+) and a.whhgid=w.id (+)

has two tables

Table1

USER_ID user_name User_ps Tutorial S

1 AAA A

2 BBB b

3 CCC C

Table2

USER_ID User_power

1 111000

2 000111

Querying using SQL statements

Normal state:

Select table1.user_id,

Table1.user_name,

Table2.user_power

From Table1,table2

where table1.user_id = table2.user_id

But this retrieves only two of the data:

USER_ID user_name User_power

1 AAA 000111

2 BBB 111000

Enter the text you want to convert,

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Select Table1.user_id,table1.user_name,table2.user_power

From Table1,table2

where table1.user_id (+) = table2.user_id

We can get the following results

USER_ID user_name User_power

1 AAA 000111

2 BBB 111000

3 CCC (NULL)