I have table like this :
ID | key | value
1 | A1 |o1
1 | A2 |o2
1 | A3 |o3
2 | A1 |o4
2 | A2 |o5
3 | A1 |o6
3 | A3 |o7
4 | A3 |o8
I want to write a oracle query that can filter value column based on key column .
some thing like this
select ID
where
if key = A1 then value ='o1'
and key = A3 then value ='o4'
please help me to write this query.
***To clarify my question ,I need list of IDs in result that all condition(key-value) are true for them. for each IDs I should check key-values (with AND ) and if all conditions are true then this ID is acceptable .
thanks
IF means PL/SQL. In SQL, we use CASE expression instead (or DECODE, if you want). Doing so, you'd move value out of the expression and use something like this:
where id = 1
and value = case when key = 'A1' then 'o1'
when key = 'A3' then 'o4'
end
You are mixing filtering and selection. List the columns that you want to display in the SELECT list and the columns used to filter in the WHERE clause
SELECT key, value
FROM my_table
WHERE ID = 1 AND key IN ('A1', 'A2')
If there is no value column in your table, you can use the DECODE function
SELECT key, DECODE(key, 'A1', 'o1', 'A2', 'o4', key) AS value
FROM my_table
WHERE ID = 1
After the key, you must specify pairs of search and result values. The pairs can be followed by a default value. In this example, since we did not specify a result for 'A3', the result will be the key itself. If no default value was specified, NULL would be returned for missing search values.
update
It seems that I have misunderstood the question (see #mathguy's comment). You can filter the way you want by simply using the Boolean operators AND and OR
SELECT * FROM
FROM my_table
WHERE
ID = 1 AND
(
key = 'A1' AND value ='o1' OR
key = 'A3' AND value ='o4'
)
By using this pattern it is easy to add more constraints of this kind. Note that AND has precedence over OR (like * over +).
Related
id value
1 a
2 b
3 c
How do i add second value 'z' to id=1 (separated by comma)?
id value
1 a,z
2 b
3 c
and how to remove the 'z' now if i have that final table?
You can use update:
update t
set value = concat(value, ',z')
where id = 1;
To answer your secondary question, yes.
If you run Select value from table where id = 1 it will return a,z. that means that if you are going to use it again in queries, you will quite possibly need to utilize a Split() type function, dependent on what you're doing with it.
The best and simplest way to do this is the following query according to me :
update table1 set value = concat(value,'z') where id = 1
where : Table1 is the name of your table.
Suppose I have a PostgreSQL table t that looks like
id | name | y
----+------+---
0 | 'a' | 0
1 | 'b' | 0
2 | 'c' | 0
3 | 'd' | 1
4 | 'e' | 2
5 | 'f' | 2
With id being the primary key and with a UNIQUE constraint on (name, y).
Suppose I want to update this table in such a way that the part of the data set with y = 0 becomes (without knowing what is already there)
id | name | y
----+------+---
0 | 'a' | 0
1 | 'x' | 0
2 | 'y' | 0
I could use
DELETE FROM t WHERE y = 0 AND name NOT IN ('a', 'x', 'y');
INSERT INTO t (name, y) VALUES ('a', 0), ('x', 0), ('y', 0)
ON CONFLICT (name) DO NOTHING;
I feel like there must be a one-statement way to do this (like what upsert does for the task "update the existing entries and insert missing ones", but then for "insert the missing entries and delete the entries that should not be there"). Is there? I heard rumours that oracle has something called MERGE... I'm not sure what it does exactly.
This can be done with a single statement. But I doubt whether that classifies as "simpler".
Additionally: your expected output doesn't make sense.
Your insert statement does not provide a value for the primary key column (id), so apparently, the id column is a generated (identity/serial) column.
But in that case, news rows can't have the same IDs as the ones before because when the new rows were inserted, new IDs were generated.
Given the above change to your expected output, the following does what you want:
with data (name, y) as (
values ('a', 0), ('x', 0), ('y', 0)
), changed as (
insert into t (name, y)
select *
from data
on conflict (name,y) do nothing
)
delete from t
where (name, y) not in (select name, y from data);
That is one statement, but certainly not "simpler". The only advantage I can see is that you do not have to specify the list of values twice.
Online example: https://rextester.com/KKB30299
Unless there's a tremendous number of rows to be updated, do it as three update statements.
update t set name = 'a' where id = 0;
update t set name = 'x' where id = 1;
update t set name = 'y' where id = 2;
This is simple. It's easily done in a loop with a SQL builder. There's no race conditions as there are with deleting and inserting. And it preserves the ids and other columns of those rows.
To demonstrate with some psuedo-Ruby code.
new_names = ['a', 'x', 'y']
# In a transaction
db.transaction {
# Query the matching IDs in the same order as their new names
ids_to_update = db.select("
select id from t where y = 0 order by id
")
# Iterate through the IDs and new names together
ids_to_update.zip(new_names).each { |id,name|
# Update the row with its new name
db.execute("
update t set name = ? where id = ?
", name, id)
}
}
Fooling around some, here's how I did it in "one" statement, or at least one thing sent to the server, while preserving the IDs and no race conditions.
do $$
declare change text[];
declare changes text[][];
begin
select array_agg(array[id::text,name])
into changes
from unnest(
(select array_agg(id order by id) from t where y = 0),
array['a','y','z']
) with ordinality as a(id, name);
foreach change slice 1 in array changes
loop
update t set name = change[2] where id = change[1]::int;
end loop;
end$$;
The goal is to produce an array of arrays matching the id to its new name. That can be iterated over to do the updates.
unnest(
(select array_agg(id order by id) from t where y = 0),
array['a','y','z']
) with ordinality as a(id, name);
That bit produces rows with the IDs and their new names side by side.
select array_agg(array[id::text,name])
into changes
from unnest(...) with ordinality as a(id, name);
Then those rows of IDs and names are turned into an array of arrays like: {{1,a},{2,y},{3,z}}. (There's probably a more direct way to do that)
foreach change slice 1 in array changes
loop
update t set name = change[2] where id = change[1]::int;
end loop;
Finally we loop over the array and use it to perform each update.
You can turn this into a proper function and pass in the y value to match and the array of names to change them to. You should verify that the length of the ids and names match.
This might be faster, depends on how many rows you're updating, but it isn't simpler, and it took some time to puzzle out.
So I found these 2 articles but they don't quite answer my question...
Find max value and show corresponding value from different field in SQL server
Find max value and show corresponding value from different field in MS Access
I have a table like this...
ID Type Date
1 Initial 1/5/15
1 Periodic 3/5/15
2 Initial 2/5/15
3 Initial 1/10/15
3 Periodic 3/6/15
4
5 Initial 3/8/15
I need to get all of the ID numbers that are "Periodic" or NULL and corresponding date. So I want a to get query results that looks like this...
ID Type Date
1 Periodic 3/5/15
3 Periodic 3/6/15
4
I've tried
select id, type, date1
from Table1 as t
where type in (select type
from Table1 as t2
where ((t2.type) Is Null) or "" or ("periodic"));
But this doesn't work... From what I've read about NULL you can't compare null values...
Why in SQL NULL can't match with NULL?
So I tried
SELECT id, type, date1
FROM Table1 AS t
WHERE type in (select type
from Table1 as t2
where ((t.Type)<>"Initial"));
But this doesn't give me the ID of 4...
Any suggestions?
Unless I'm missing something, you just want:
select id, type, date1
from Table1 as t
where (t.type Is Null) or (t.type = "") or (t.type = "periodic");
The or applies to boolean expressions, not to values being compared.
Phone_book
+----+---------+-----------+--------------+
| id | key | code | value |
+----+---------+-----------+--------------+
| 1 | MAX_VAL | 111 | reset |
+----+------+--------------+--------------+
| 2 | MIN_VAL | 222 | set |
+----+------+--------------+--------------+
| 3 | MIN_VAL | 0 | NA |
+----+---------+-----------+--------------+
Key and code combination is the primary key.
Requirement:
if KEY and CODE is present, return VALUE.
if KEY is present and CODE not exist return the VALUE of CODE 0.
Implementation:
Achieved this with using multiple query. Syntax used is for JPQL
1) "SELECT param FROM Phone_book param WHERE upper(key)=:paramKey AND code=:estCode";
if this returns null, while shoot another query
2) "SELECT param FROM Phone_book param WHERE upper(key)=:paramKey AND code=:O";
What I looking for :
Can I achieve this in one query, or a better way ?
Thanks in advance.
In Oracle SQL, the below will suffice your need. No need to write PLSQL for this.
SELECT key,
nvl(code,0) -- This will make sure if code is null then value is 0
FROM Phone_book
WHERE (key is not NULL AND CODE IS NOT NULL) -- This will help in fetching value when KEY and CODE is present
OR ( key is not null and code is null); -- This will help in fetching value when KEY is present and CODE is null.
MySQL Relevant because the question was tagged MySQL initially
You can give it a try:
SELECT
defaultTable.`key`,
COALESCE(queryTable.`value`,defaultTable.`value`) AS v
FROM
(
SELECT
`key`,
`value`
FROM Phone_book
WHERE UPPER(`key`) = ?
AND `code` = 0
) AS defaultTable
LEFT JOIN
(
SELECT
`key`,
`value`
FROM Phone_book
WHERE UPPER(`key`) = ?
AND `code` = ?
) AS queryTable
ON defaultTable.`key` = queryTable.`key`;
Note: Replace the question marks by your provided values.
When there doesn't exist any record for the supplied key and code values then queryTable.value will be NULL.
So COALESCE will pick the value from defaulTable if any.
select
case
when key is not null and code is not null then value
when key is not null and code is null then 0
end
from phone_book;
select value from (
select value, row_number() over (order by case when code = 0 then 2 else 1 end) rn
from phonebook pb
where upper(key) = :paramKey and (code = :estCode or code = 0))
where rn = 1
Select values having requested key and requested code or code 0. Sort them properly with function row_number and take first value.
Lets say I have a schema:
key STRING NULLABLE
values INTEGER REPEATED
Now, please note that second column is a repeated field of integers,
Lets say the data is something like:
key:'abc'
values: 1 2 3 (3 separate values, same for below values)
key:'def'
values: 1 2 5
key:'ghi'
values: 1 6 9
And here I wish to find out keys which has values 1 and 2 ? Expecting 'abc' and 'def' as result set.
Looking for a query for this. I want an 'and' ('in' does not work here). I need those both values to be present for any key to return as result.
SELECT
key,
SUM(values = 1 or values = 2) WITHIN RECORD AS check
FROM yourtable
HAVING check = 2