I have a select statement like below
select *
from employees
where emp_id <= v_emp_id;
I want this emp_id to be <= v_emp_id if country is not USA.
If country is USA, then I want emp_id to be = v_usa_emp_id.
Your question is a bit ambiguous. I have assumed that country is an attribute in the table employees of data type VARCHAR.
SELECT * FROM employees
WHERE
(emp_id = v_emp_id AND country = 'USA')
OR (emp_id <= v_emp_id AND country != 'USA')
You might want to take a look at WHERE, OR and AND.
Quoting the OR page linked above:
If you use multiple logical operators in a statement, Oracle evaluates the OR operators after the NOT and AND operators. However, you can change the order of evaluation by using parentheses.
Related
I'd like to combine multiple unrelated searches into 1 single query but also be able to add a "reference" to tell apart which records belong to which queries.
Example:
SELECT * FROM users WHERE
(name ILIKE '%mark smith%' AND country='US') // condition id #1
OR
(name ILIKE '%christine smith%') // condition id #2
OR
... + 1000 queries
How can i tell which users match which condition without running a client-side ILIKE simulation on all returned records?
In other words, is there a Postgres pattern to add references to conditions somehow?
condition_1_users = [...]
condition_2_users = [...]
etc..
You can replicate your filtering logic into a CASE expression in the select clause:
SELECT *, CASE WHEN name ILIKE '%mark smith%' AND country = 'US'
THEN 1
WHEN name ILIKE '%christine smith%'
THEN 2
... END AS condition
FROM users
WHERE
(name ILIKE '%mark smith%' AND country = 'US')
OR
(name ILIKE '%christine smith%')
...
SUMMARY: I've two tables I want to derive info out of: family_values (family_name, item_regex) and product_ids (product_id) to be able to update the property family_name in a third.
Here the plan is to grab a json array from the small family_values table and use the column value item_regex to do a test match against the product_id for every row in product_ids.
MORE DETAILS: Importing static data from CSV to table of orders. But, in evaluating cost of goods and market value I'm needing to continuously determine family from a prefix regex (item_regex from family_values) match on the product_id.
On the client this looks like this:
const families = {
FOOBAR: 'Big Ogre',
FOOBA: 'Wood Elf',
FOO: 'Valkyrie'
};
// And to find family, and subsequently COGs and Market Value:
const findFamily = product_id => Object.keys(families).find(f => new RegExp('^' + f).test(product_id));
This is a huge hit for the client so I made a family_values table in PG to include a representative: family_name, item_regex, cogs, market_value.
Then, the product_ids has a list of only the products the app cares about (out of millions). This is actually used with an insert trigger 'on before' to ignore any CSV entries that aren't in the product_ids view. So, I guess after that the product_ids view could be taken out of the equation because the orders, after inserting readonly data, has its own matching product_id. It does NOT have family_name, so I still have the issue of determining that client-side.
PSUEDO CODE: update family column of orders with family_name from family_values regex match against orders.product_id
OR update the product_ids table with a new family column and use that with the existing on insert trigger (used to left pad zeros and normalize data right now). Now I'm thinking this may be just an update as suggested, but not real good with regex in PG. I'm a PG novice.
PROBLEM: But, I'm having a hangup in doing what I thought would be like a JS Array Find operation. The family_values have been sorted on the item_regex so that the most strict match would be on top, and therefor found first.
For example, with sorting we have:
family_values_array = [
{"family_name": "Big Ogre", "item_regex": "FOOBAR"},
{"family_name": "Wood Elf", "item_regex": "FOOBA"},
{"family_name": "Valkyrie", "item_regex": "FOO"}]
So, that the comparison of product_id of ^FOOBA would yield family "Wood Elf".
SOLUTION:
The solution I finally came about using was simply using concat to write out the front-anchored regex. It was so simple in the end. The key line I was missing is:
select * into family_value_row from iol.family_values
where lvl3_id = product_row.lvl3_id and product_row.product_id
like concat(item_regex, '%') limit 1;
Whole function:
create or replace function iol.populate_families () returns void as $$
declare
product_row record;
family_value_row record;
begin
for product_row in
select product_id, lvl3_id from iol.products
loop
-- family_name is what we want after finding the BEST match fr a product_id against item_regex
select * into family_value_row from iol.family_values
where lvl3_id = product_row.lvl3_id and product_row.product_id like concat(item_regex, '%') limit 1;
-- update family_name and value columns
update iol.products set
family_name = family_value_row.family_name,
cog_cents = family_value_row.cog_cents,
market_value_cents = family_value_row.market_value_cents
where product_id = product_row.product_id;
end loop;
end;
$$
LANGUAGE plpgsql;
Use concat as updated above:
select * into family_value_row from iol.family_values
where lvl3_id = product_row.lvl3_id and product_row.product_id
like concat(item_regex, '%') limit 1;
I'm trying to parameterize my postgresql query in order to prevent SQL injection in my ruby on rails application. The SQL query will sum a different value in my table depending on the input.
Here is a simplified version of my function:
def self.calculate_value(value)
calculated_value = ""
if value == "quantity"
calculated_value = "COALESCE(sum(amount), 0)"
elsif value == "retail"
calculated_value = "COALESCE(sum(amount * price), 0)"
elsif value == "wholesale"
calculated_value = "COALESCE(sum(amount * cost), 0)"
end
query = <<-SQL
select CAST(? AS DOUBLE PRECISION) as ? from table1
SQL
return Table1.find_by_sql([query, calculated_value, value])
end
If I call calculate_value("retail"), it will execute the query like this:
select location, CAST('COALESCE(sum(amount * price), 0)' AS DOUBLE PRECISION) as 'retail' from table1 group by location
This results in an error. I want it to execute without the quotes like this:
select location, CAST(COALESCE(sum(amount * price), 0) AS DOUBLE PRECISION) as retail from table1 group by location
I understand that the addition of quotations is what prevents the sql injection but how would I prevent it in this case? What is the best way to handle this scenario?
NOTE: This is a simplified version of the queries I'll be writing and I'll want to use find_by_sql.
Prepared statement can not change query structure: table or column names, order by clause, function names and so on. Only literals can be changed this way.
Where is SQL injection? You are not going to put a user-defined value in the query text. Instead, you check the given value against the allowed list and use only your own written parts of SQL. In this case, there is no danger of SQL injection.
I also want to link to this article. It is safe to create a query text dynamically if you control all parts of that query. And it's much better for RDBMS than some smart logic in query.
I have a table containing transactions with an amount. I want to create a batch of transactions so that the sum of amount of each 'group by' is negative.
My problematic is to get all ids of the rows concerned by a 'group by' where each group is validate by a sum condition.
I find many solutions which don't work for me.
The best solution I found is to request the db a first time with the 'group by' and the sum, then return ids to finally request the db another time with all of them.
Here an example of what I would like (it doesn't work!) :
SELECT * FROM transaction_table transaction
AND transaction.id IN (
select string_agg(grouped::character varying, ',' ) from (
SELECT array_agg(transaction2.id) as grouped FROM transaction_table transaction2
WHERE transaction2.c_scte='c'
AND (same conditions)
GROUP BY
transaction2.motto ,
transaction2.accountBnf ,
transaction2.payment ,
transaction2.accountClt
HAVING sum(transaction2.amount)<0
)
);
the result of the array_agg is like:
{39758,39759}
{39757,39756,39755,39743,39727,39713}
and the string_agg is :
{39758,39759},{39757,39756,39755,39743,39727,39713}
Now I just need to use them but I don't know how to...
unfortunatly, it doesn't work because of type casting :
ERROR: operator does not exist: integer = integer[]
Indice : No operator matches the given name and argument type(s). You might need to add explicit type casts.
Maybe you are looking for
SELECT id, motto, accountbnf, payment, accountclnt, amount
FROM (SELECT id, motto, accountbnf, payment, accountclnt, amount,
sum(amount)
OVER (PARTITION BY motto, accountbnf, payment, accountclnt)
AS group_total
FROM transaction_table) AS q
WHERE group_total < 0;
The inner SELECT adds an additional column using a window function that calculates the sum for each group, and the outer query removes all results where that sum is not negative.
Finally I found this option using the 'unnest' method. It works perfectly.
Array_agg bring together all ids in different array
unnest flattened all of them
This comes from here
SELECT * FROM transaction_table transaction
WHERE transaction.id = ANY(
SELECT unnest(array_agg(transaction2.id)) as grouped FROM transaction_table transaction2
WHERE transaction2.c_scte='c'
AND (same conditions)
GROUP BY
transaction2.motto ,
transaction2.accountBnf ,
transaction2.payment ,
transaction2.accountClt
HAVING sum(transaction2.amount)<0
);
The problem with this solution is that hibernate doesn't take into account the array_agg method.
I have a genuine use-case which requires referring to column aliases in a "where" clause. I'm trying to use the techniques outlined here, which I expect to work in Sybase and MySQL but don't seem to work in either H2 or HSQLDB:
http://databases.aspfaq.com/database/how-do-i-use-a-select-list-alias-in-the-where-or-group-by-clause.html
If you'd be kind enough to try and recreate my issue, here's how you can do it:
create table CUSTOMER (code varchar(255), description varchar(255), active bit, accountOpeningDate date, currentBalance numeric(20,6), currentBalanceDigits int)
insert into CUSTOMER (code, description, active, accountOpeningDate, currentBalance, currentBalanceDigits) values ('BMW', 'BMW Motors', 0, '2011-01-01', 345.66, 2)
insert into CUSTOMER (code, description, active, accountOpeningDate, currentBalance, currentBalanceDigits) values ('MERC', 'Mercedes Motors', 1, '2012-02-02', 14032, 0)
Then, this SQL query fails:
select nest.* from (
select CODE "id", DESCRIPTION "description",
ACTIVE "active",
accountOpeningDate "accountOpeningDate",
currentBalance "currentBalance"
from customer
) as nest
where nest.id = 'BMW'
It's fine if you strip of the "where nest.id = 'BMW'". However, trying to use any of the aliases in either the where clause or the select clause (nest.id rather than next.*) then the query fails. Error code is Column "NEST.ID" not found; ... [42122-167] 42S22/42122
The same failure occurs if you try and create a view with aliased column names then try and select from the view. For example:
create view customer_view as
select CODE "id", DESCRIPTION "description",
ACTIVE "active",
accountOpeningDate "accountOpeningDate",
currentBalance "currentBalance"
from customer
Then:
select id from customer_view
The problem is the mixed usage of unquoted and quoted identifiers. According to the SQL specification, unquoted identifiers (such as id) are case insensitive, and the database might convert them to uppercase or lowercase. Quotes identifiers (such as "id") are case sensitive, and the database engine must not convert the identifier.
H2 converts unquoted identifiers to uppercase (like other database engines such as Oracle). In your query, you have used both quoted and unquoted identifiers. Simplied test case (fails for H2 and other databases):
select * from (select 1 "id") where id = 1
To solve the problem, you need to use either quoted identifiers everywhere, or unquoted identifiers:
select * from (select 1 id) where id = 1
or
select * from (select 1 "id") where "id" = 1