getting mutually exclusive data from 2 tables

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April 30th, 2003, 02:06 AM

shafan

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getting mutually exclusive data from 2 tables :SOLVED

Hi,
I'm trying to extract all the records which DO NOT exist in another table based on a joined field.
Is there another way of doing it besides
"...WHERE JoinedFieldValue NOT IN( comma seperated value list)" ?

thanx

Last edited by shafan : May 4th, 2003 at 02:12 AM.

April 30th, 2003, 02:30 AM

NoXcuz

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Use a left join like
SELECT t1.* FROM table1 t1 LEFT JOIN table2 t2 ON t1.id = t2.id WHERE t2.id IS NULL

//NoXcuz

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April 30th, 2003, 04:19 AM

shafan

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no good.
for example:
I have in table 1 IDs 1, 2, 5
and in table 2 IDs 1, 2, 3, 4, 5

I want a query that will return IDs 3 and 4 (the ones which are not present in both tables).

There are no Null values in the compared field.

thanx

April 30th, 2003, 05:12 AM

NoXcuz

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I don't know what you tried, but with your given example in Postgresql:

Code:

test=# create table table1 (
test(# id int);
CREATE
test=# insert into table1 values (1);
INSERT 22516 1
test=# insert into table1 values (2);
INSERT 22517 1
test=# insert into table1 values (5);
INSERT 22518 1
test=# create table table2 (
test(# id int);
CREATE
test=# insert into table2 values (1);
INSERT 22521 1
test=# insert into table2 values (2);
INSERT 22522 1
test=# insert into table2 values (3);
INSERT 22523 1
test=# insert into table2 values (4);
INSERT 22524 1
test=# insert into table2 values (5);
INSERT 22525 1
test=# SELECT t2.id FROM table2 t2 LEFT JOIN table1 t1 ON t2.id = t1.id WHERE t1.id IS NULL;
 id
----
  3
  4
(2 rows)

Using a LEFT JOIN (or RIGHT JOIN) will produce NULL values in the above context, wheter the table itself contains them or not.

//NoXcuz

April 30th, 2003, 05:57 AM

shafan

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I didn't provide all the information.
The tables sit in diferent data bases: one is Access2000 and the other is FoxPro 6.

I have 2 ADO connections - can't use a JOIN.

Sorry...

April 30th, 2003, 06:08 AM

NoXcuz

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Two alternatives as I see it.

Use a scripting language and arrays
If the result sets aren't too big, you can select all id' from table1 and store them in an array. Then do the same hing for table2 and compare the arrays. The difference is your answer...
Temporary (or permanent) tables in either database
Don't know if Acess or Foxpro supports temporary tables, but if they don't you could create a table to store the result and drop it afterwards. Say that you use Access for example. Do a 'select all id's from foxpro-table' and create a table in Access where you store the result set. Then you can run the query in my previous post to get the difference.

//NoXcuz

May 4th, 2003, 02:11 AM

shafan

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I've filled 2 arrays and then compared them.

Thanks!

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