Basic Join with Rowid

marcopo · #1 (**permalink**) 01-21-13, 10:12

Hi,

I have got a basic question but in my database it will not work.

I have two tables. Both have the similar amount of rows. I want to add one column of the first table into the second table. Here, the values should be in the same order as before. Table1.row1 = Table2.row1; Table1.row2 = Table2.row2 ; Table1.row3 = Table2.row3....Table1.row(n) = Table2.row(n).

The issue is, there is no really connector for a join. I tried with rowid, but no selected row is presented. (permanently is the column I will add)

Code:

SElECT tab.rowid rid
nvl(permanently2, permanently) permanently,
tab2.rowid bum
    from  tab,
            tab2
                 where tab.rowid= tab1.rowid;

Thanks

anacedent · #2 (**permalink**) 01-21-13, 10:15

rows in a tables are like balls in a basket.
rows in a table have NO inherent order!

which ball in a basket is the "first" ball?
which ball in a basket is the "next" ball?

Simply put the "requirement" makes no sense.

anacedent · #3 (**permalink**) 01-21-13, 10:30

ROWID Pseudocolumn

rowid are guaranteed to be unique & therefore can NEVER be equal to another rowid.

marcopo · #4 (**permalink**) 01-21-13, 10:45

and rownum?

anacedent · #5 (**permalink**) 01-21-13, 10:55

how many columns in TABLE1?
how many columns in TABLE2?

what happens when TABLE1 & TABLE2 have different number of rows?

anacedent · #6 (**permalink**) 01-21-13, 11:23

Quote:

Originally Posted by marcopo

and rownum?

what about rownum?

SELECT * FROM TABLE1 ORDER BY COLUMN1;

does query above have same "first row" (ROWNUM=1) as query below?

SELECT * FROM TABLE1 ORDER BY COLUMN2;

so exactly which row is "first row" from TABLE1?

Celko · #7 (**permalink**) 01-22-13, 14:05

Quote:

Originally Posted by marcopo

and rownum?

It is how non-RDBMS programmers mimic a 1950's magnetic tape. Their mindsets cannot handle abstractions like keys, sets, data types, etc. They live in a world of punch cards and physical files.

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