oracle sql列别名

Question

I have 3 tables A, B, c and I want to join those tables. These tables have common columns like, id_no, order_no

and i want to write a query that returns all columns from all 3 tables with column name extension like tabA., tabB., tabC....I don't want to manually specify all column names. In that way i can differentiate the common columns among tables.

select tabA.id_no, tabA.order_no, tabA....., tabB.id_no, tabB.order_no,tabB..., tabC.id_no, tabC.order_no,tabC..
from A tabA, B tabB, C tabC
where tabA.id_no = tabB.id_no
and tabB.id_no = tabC.id_no

could u pls let me know how to achieve this in oracle sql.

Answer 1

Oracle SQL Developer can do that.

Write your * query, put your mouse over the '*'

SQL Developer offers to explode that to the fully qualified column list, click the blue text.

Ta-da.

Don't forget your WHERE clause or ANSI join in the FROM, or your DBA will explain to you what a Cartesian product is.

If your table has foreign keys, SQLDev can generate that as well.

Answer 2

You can do the following:

SELECT tabA.*, tabB.*, tabC.*
  FROM a tabA INNER JOIN b tabB
    ON tabA.id_no = tabB.id_no
 INNER JOIN c tabC
    ON tabB.id_no = tabC.id_no;

EDIT

If you want only to get a list of the columns associated with the three tables, and to see which column names are common among the three, then you can try something like the following:

SELECT column_name, COUNT(*), LISTAGG(table_name, ',') WITHIN GROUP ( ORDER BY table_name
  FROM all_tab_columns
 WHERE owner = '<table_owner>'
   AND table_name IN ('A','B','C')
 GROUP BY column_name;

NB LISTAGG() assumes you're using Oracle 11g or greater; prior to that you can use the undocumented function WM_CONCAT() .

Hope this helps.