Under the simplified function:
The table has A username field
Table B have a username, testa, testc
Table C have the username, testb testd, teste
-- -- -- -- -- -- -- -- -- --
Now want to query data from tables B and C testa or testb, conditions the username is equal to the table A username
If the table has data from table B B testa, table with data from the table C C testb, both table data from table B testa,

How to write the SQL?

CodePudding user response:

There is a thing called the stored procedure

CodePudding user response:

Have a sample data?

CodePudding user response:

The select a.u sername. NVL (testa, testb)
From A A, outer B B, outer C C
Where a.u sername=b.u sername
And a.u sername=c.u sername