I am trying to merge multiple tables that have a common column name which need not have the same values across the tables. For ex,
-tmp1-
id dat
1 234
2 432
3 412
-tmp2-
id nom
1 jim
2
3 ryan
4 jack
-tmp3-
id pin
1 gi23
2 x4ed
3 yit42
8 hiu11
If above are the input, the output needs to be,
id dat nom pin
1 234 jim gi23
2 432 x4ed
3 412 ryan yit42
4 jack
8 hiu11
Thanks in advance.
postgresql 8.2.15 on greenplum from R(pass-through queries)
use FULL JOIN ... USING (id) syntax.
please see example: http://sqlfiddle.com/#!12/3aff2/1
this is how diffrent join types work (provided that tab1.row3 meets joining condition with tab2.row1, and tab1.row3 meets tab2.row2):
| tab1 | | tab2 | | JOIN | | LEFT JOIN | | RIGHT JOIN | | FULL JOIN |
-------- -------- ------------------------- ------------------------- ------------------------- -------------------------
| row1 | | tab1.row1 | | tab1.row1 |
| row2 | | tab1.row2 | | tab1.row2 |
| row3 | | row1 | | tab1.row3 | tab2.row1 | | tab1.row3 | tab2.row1 | | tab1.row3 | tab2.row1 | | tab1.row3 | tab2.row1 |
| row4 | | row2 | | tab1.row4 | tab2.row2 | | tab1.row4 | tab2.row2 | | tab1.row4 | tab2.row2 | | tab1.row4 | tab2.row2 |
| row3 | | tab2.row3 | | tab2.row3 |
| row4 | | tab2.row4 | | tab2.row4 |
Related
I am a novice self-teaching Microsoft Access.
I have an MS Access database with a table of students (Table1).
Table1
+----+-----------+----------+------------+------------+
| id | firstname | lastname | Year_Group | Form_Group |
+----+-----------+----------+------------+------------+
| 2 | mnb | nbgfv | 7 | 1 |
| 3 | jhg | uhgf | 8 | 2 |
| 4 | poi | ijuy | 9 | 2 |
| 5 | tgf | tgfd | 10 | 2 |
| 6 | wer | qwes | 11 | 2 |
+----+-----------+----------+------------+------------+
Every day students days are recorded sort of like Table2.
Table2
+----------+----+-----------+----------+------------+--------+-----------+----------+
| Date | id | firstname | lastname | Year_Group | Effort | Behaviour | Homework |
+----------+----+-----------+----------+------------+--------+-----------+----------+
| 28/02/19 | 2 | mnb | nbgfv | 7 | Good | Good | Y |
| 28/02/19 | 3 | jhg | uhgf | 8 | OK | OK | Y |
| 28/02/19 | 4 | poi | ijuy | 9 | Bad | Bad | N |
| 01/03/19 | 5 | tgf | tgfd | 10 | Good | OK | Y |
| 01/03/19 | 6 | wer | qwes | 11 | Good | Good | Y |
+----------+----+-----------+----------+------------+--------+-----------+----------+
Is there a way (when using a list box or combo box) to select a student from Table1 so that their information is used for the corresponding columns in Table2?
Or is there a more efficient way to do this?
Firstly, you should normalise your data.
Currently, you are repeating the firstname, lastname, and Year_Group data in two separate tables, which not only bloats your database, but also means that such data must be maintained in two separate places, potentially leading to inconsistencies and then uncertainty as to which is the master.
Instead, I would suggest that your Students table should contain all information pertaining to the characteristics of a student:
Students
+----+-----------+----------+------------+------------+
| id | firstname | lastname | Year_Group | Form_Group |
+----+-----------+----------+------------+------------+
| 2 | mnb | nbgfv | 7 | 1 |
| 3 | jhg | uhgf | 8 | 2 |
| 4 | poi | ijuy | 9 | 2 |
| 5 | tgf | tgfd | 10 | 2 |
| 6 | wer | qwes | 11 | 2 |
+----+-----------+----------+------------+------------+
And the information pertaining to each school day should only reference the student ID in the Students table:
SchoolDays
+----------+----+--------+-----------+----------+
| Date | id | Effort | Behaviour | Homework |
+----------+----+--------+-----------+----------+
| 28/02/19 | 2 | Good | Good | Y |
| 28/02/19 | 3 | OK | OK | Y |
| 28/02/19 | 4 | Bad | Bad | N |
| 01/03/19 | 5 | Good | OK | Y |
| 01/03/19 | 6 | Good | Good | Y |
+----------+----+--------+-----------+----------+
Then, if you want to display the data in its entirety, you would use a query which joins the two tables, e.g.:
select
t2.date,
t1.firstname,
t1.lastname,
t1.year_group,
t2.effort,
t2.behaviour,
t2.homework
from
students t1 inner join schooldays t2 on t1.id = t2.id
I have two subqueries. Here is the output of subquery A....
id | date_lat_lng | stat_total | rnum
-------+--------------------+------------+------
16820 | 2016_10_05_10_3802 | 9 | 2
15701 | 2016_10_05_10_3802 | 9 | 3
16821 | 2016_10_05_11_3802 | 16 | 2
17861 | 2016_10_05_11_3802 | 16 | 3
16840 | 2016_10_05_12_3683 | 42 | 2
17831 | 2016_10_05_12_3767 | 0 | 2
17862 | 2016_10_05_12_3802 | 11 | 2
17888 | 2016_10_05_13_3683 | 35 | 2
17833 | 2016_10_05_13_3767 | 24 | 2
16823 | 2016_10_05_13_3802 | 24 | 2
and subquery B, in which date_lat_lng and stat_total has commonality with subquery A, but id does not.
id | date_lat_lng | stat_total | rnum
-------+--------------------+------------+------
17860 | 2016_10_05_10_3802 | 9 | 1
15702 | 2016_10_05_11_3802 | 16 | 1
17887 | 2016_10_05_12_3683 | 42 | 1
15630 | 2016_10_05_12_3767 | 20 | 1
16822 | 2016_10_05_12_3802 | 20 | 1
16841 | 2016_10_05_13_3683 | 35 | 1
15632 | 2016_10_05_13_3767 | 23 | 1
17863 | 2016_10_05_13_3802 | 3 | 1
16842 | 2016_10_05_14_3683 | 32 | 1
15633 | 2016_10_05_14_3767 | 12 | 1
Both subquery A and B pull data from the same table. I want to delete the rows in that table that share the same ID as subquery A but only where date_lat_lng and stat_total have a shared match in subquery B.
Effectively I need:
DELETE FROM table WHERE
id IN
(SELECT id FROM (subqueryA) WHERE
subqueryA.date_lat_lng=subqueryB.date_lat_lng
AND subqueryA.stat_total=subqueryB.stat_total)
Except I'm not sure where to place subquery B, or if I need an entirely different structure.
Something like this,
DELETE FROM table WHERE
id IN (
SELECT DISTINCT id
FROM subqueryA
JOIN subqueryB
USING (id,date_lat_lng,stat_total)
)
I'm relatively new to PostgreSQL and trying to figure out how to solve the following scenario. Let's say I have three tables:
stores
| store_id |
|----------|
| 1 |
| 2 |
| 3 |
products
| product_id |
|------------|
| 1 |
| 2 |
| 3 |
store_has_product
| store_id | product_id |
|----------|------------|
| 1 | 3 |
| 1 | 2 |
| 2 | 1 |
| 3 | 3 |
| 1 | 1 |
| 3 | 1 |
| 3 | 2 |
And now I'm trying to build a query to join all products to the stores table and group them in an array, so that I have an output like this:
| store_id | products |
|----------|-----------|
| 1 | {3, 2, 1} |
| 2 | {2} |
| 3 | {3, 1, 2} |
I know that Arrays are possible with PostgreSQL, but I don't get how to write such a query and probably already spent too much time thinking about a solution.
Thanks for your help!
If you are using version 8.4 or later you can use array_agg:
SELECT store_id, array_agg(product_id::text) as products
FROM store_has_product
GROUP BY store_id
For example I have a table called product_list, which holds a list of products:
+----+-------+-----------+-------------+--+
| id | name | weight(g) | type | |
+----+-------+-----------+-------------+--+
| 1 | Shirt | 157 | Clothes | |
+----+-------+-----------+-------------+--+
| 2 | Ring | 53 | Accessories | |
+----+-------+-----------+-------------+--+
| 3 | Pants | 202 | Clothes | |
+----+-------+-----------+-------------+--+
and a table called product_price:
+----------+----+-------+--------+--+
| price_id | id | name | price | |
+----------+----+-------+--------+--+
| 1 | 1 | Shirt | 99.00 | |
+----------+----+-------+--------+--+
| 2 | 2 | Ring | 149.00 | |
+----------+----+-------+--------+--+
| 3 | 3 | Pants | 119.00 | |
+----------+----+-------+--------+--+
If I insert 1 row of data into product_list, part of the data (such as product_id & product name) should also be inserted in another table like product_price which holds the price for all products (new products would have 0 or NULL values for their price). Eg:
product_list:
+----+--------+-----------+-------------+--+
| id | name | weight(g) | type | |
+----+--------+-----------+-------------+--+
| 1 | Shirt | 157 | Clothes | |
+----+--------+-----------+-------------+--+
| 2 | Ring | 53 | Accessories | |
+----+--------+-----------+-------------+--+
| 3 | Pants | 202 | Clothes | |
+----+--------+-----------+-------------+--+
| 4 | Shirt2 | 175 | Clothes | |
+----+--------+-----------+-------------+--+
product_price:
+----------+----+-------+--------+--+
| price_id | id | name | price | |
+----------+----+-------+--------+--+
| 1 | 1 | Shirt | 99.00 | |
+----------+----+-------+--------+--+
| 2 | 2 | Ring | 149.00 | |
+----------+----+-------+--------+--+
| 3 | 3 | Pants | 119.00 | |
+----------+----+-------+--------+--+
| 4 | 4 | Shirt2| 0.00 | |
+----------+----+-------+--------+--+
My question here is the method in approaching this. What is the proper way (in a professional manner) would an experienced person approach this matter?
These are 2 approaches I have in mind:
1 - Using triggers to insert into the other tables like product_price,etc whenever I insert a product data into product_list
2 - Using a function (stored procedure) like product_add to add a new product into each tables.
Which method is better? Or if there a better suggestion, then I'd like to know about it. Thanks in advance.
TLDR: Should I use Triggers or instead use Stored Procedures, which is better? Or you have a better suggestion?
In Postgres, you can use CTEs:
with pl as (
insert into product_list(name, weight, type)
select . . .
returning *
)
insert into product_price(id, price)
select id, NULL
from pl;
Note: You shouldn't repeat the name column in the product_list and product_price table. It should only be in the list table.
I have three tables.
table a
| uid | name | number |
|-----+---------+--------|
| 1 | table | 1 |
| 2 | chair | 2 |
table b
| uid | name | number |
|-----+---------+--------|
| 1 | john | 1 |
| 2 | billy | 0 |
| 3 | bob | 2 |
| 4 | sally | 1 |
table c
| uid | table a | john | billy | bob | sally |
|-----+---------+--------+--------+-------|-------|
| 1 | table | T | | | T |
| 2 | chair | | | C | |
What I need to be able to do is look at the column names in table c, find the corresponding row entry in table b and if the numbers are the same as the numbers from table a, then set the table c value to T. Otherwise set it to C. This needs to be triggered whenever either table a or table b are updated.
How can I write an update the table using if or case statement.
Thanks.