So I have the first code which I use:
with idlist as (
Select uniqueid as masterid
From table1
Union
Select uniqueid
From table2
)
Select i.masterid,
t1.*,
t2.*
From idlist as i
Left join table1 on t1.uniqueid = i.masterid
Left join table2 on t2.uniqueid = i.masterid
Purpose of the code above: to take 2 or more tables which have the same id column and union to one row.
Second code:
select [Id], [price], [description]
from [table1]
where name_1 % 10 = 8 -- enter name_1 manually
union all
select [Id], [price], [description]
from [table2]
where name_2 % 10 = 8
Purpose of the code above: check a specific column, if it ends with '8' then list its Id, price, description
What I want:
Basically combine those two codes. I need the second code to run within the result of the first code.
I thought of creating a new table for the result of the first query above, but as far as i know i need to create all the columns before inserting data into it, yet the result of the first query will be a combination of several tables which have a lot of different columns.
Nonetheless, i still want the result of the combo between the two queries to be in a new table.
So if had to put everything to words and steps:
Select id from tables> union under the same Id to one row with all their row content > create table with the result > run the second code above on the new table
Thanks
You seem to want a bunch of columns from both tables, so I'm wondering if this accomplishes what you want:
select *
from (select t1.*
from [table1] t1
where name_1 % 10 = 8
) t1 full join
(select t2.*
from [table2] t2
where name_2 % 10 = 8
) t2
on t1.id = t2.id;
Note that this is using full join -- which is what your first query is doing (well, assuming that id is not NULL).
Also, it seems very strange to be using an arithmetic calculation (%) on a column called "name".
Related
I'm trying to join two tables but not getting the desired results. Im new to SQL and will need help to joining these two tables.
The data in Table 2 is transposed and the table will only be populated only when the "value" field is populated with random values.
Details of Table 1 and Table 2 and expected output
You could use CTEs to split up the impact from outcome. Also, your screenshot had an error for task_id 6.
with t_impact as (
select task_id, value
from table2
where name = 'task_impact'
),
t_outcome as (
select task_id, value
from table2
where name = 'task_outcome'
)
select distinct t1.id,
t1.title,
i.value as task_impact,
o.value as task_outcome
from table1 t1
left join t_impact i
on t1.id = i.task_id
left join t_outcome o
on t1.id = o.task_id
order by t1.id
DB-fiddle found here.
I have multiple SELECT queries which is ran against different tables.
The output of all the queries have the same number of rows (every query when ran individually will have the same number of rows). Is there a way I can combine the output of all these queries into a single result? (Keep out from first query and add the output of next query as a column to the output of the next query). I dont want to save these tables into database as I am just doing some validation testing.
Example:
SELECT AAA,BBB,CCC FROM Table1
SELECT Table2.DDD, Table1.AAA
FROM Table2
INNER JOIN Table1
ON Table1.AAA = Table2.AAA
I tried writing combining the query as
SELECT Table1.AAA,Table1.BBB,Table1.CCC,T1.DDD
FROM Table1,
(SELECT Table2.DDD, Table1.AAA
FROM Table2
INNER JOIN Table1
ON Table1.AAA = Table2.AAA)T1
I tried doing the above combined query, but instead of getting 11 rows as output (both queries above had result of 11 rows), I am getting 35 rows as output.
Hope the question made sense!
You'll need to specify a criteria to match each row the first query with which row of the second query.
If, for example, the column AAA is unique in both queries and you want to match rows with the same values you could do:
select a.*, b.*
from (
SELECT AAA,BBB,CCC FROM Table1
) a
full join join (
SELECT Table2.DDD, Table1.AAA
FROM Table2
INNER JOIN Table1
ON Table1.AAA = Table2.AAA
) b on b.aaa = a.aaa
If there aren't any clear matching rules, you can produce an artificial row number on each result set and use it to match rows. For example:
select
a.aaa, a.bbb, a.ccc,
b.ddd, b.aaa
from (
SELECT AAA, BBB, CCC,
row_number() over(order by aaa) as rn
FROM Table1
) a
full join join (
SELECT Table2.DDD, Table1.AAA,
row_number() over(order by table1.aaa, table2.ddd) as rn
FROM Table2
INNER JOIN Table1
ON Table1.AAA = Table2.AAA
) b on b.rn = a.rn
If you have several results and want to have all of them as additional columns you can simply use ",":
create table temp1 as select '1' as c1 from DUAL;
create table temp2 as select '2' as c2 from DUAL;
create table temp3 as select '3' as c3 from DUAL;
select a.c1, b.c2, c.c3 from temp1 a, (select c2 from temp2) b, (select c3 from temp3) c;
An alternative could also be that you want to have all the results as additional rows then you would use UNION ALL between the individual results.
I have table 1 with data and table 2 as a lookup table with metadata. I need a query that returns all records from table 1 where either column in table 1 not exists in table two.
The following query works fine for one column, but if I use more than one column in my join it´s not.
working query:
select
T1.SCENARIO,
T1.year,
T1.period,
T1.ENTITY,
T1.account,
T1.ICP,
T1.MVMTS,
T1.C1,
T1.C2,
T1.C3,
T1.MULTI_GAAP,
T1.VLAUE
from
"fccs".MV_FACT_FCCS T1
left outer join "fccs".V_META_NOT_FOUND V2 on trim(T1.account) = trim(V2.account)
where
V2.account is null
not working correctly:
select
T1.SCENARIO,
T1.year,
T1.period,
T1.ENTITY,
T1.account,
T1.ICP,
T1.MVMTS,
T1.C1,
T1.C2,
T1.C3,
T1.MULTI_GAAP,
T1.VLAUE
from
"fccs".MV_FACT_FCCS T1
left outer join "fccs".V_META_NOT_FOUND V2 on trim(T1.account) = trim(V2.account)
and trim(T1.entity) = trim(v2.entity)
where
V2.account is null or v2.entity is null
The second query continues to bring the records from table 1 where exist in table 2.
Any help appreciated!
I need a query that returns all records from table 1 where either column in table 1 not exists in table two.
Use not exists:
select ff.*
from "fccs".MV_FACT_FCCS ff
where not exists (select 1
from "fccs".V_META_NOT_FOUND mnf
where trim(ff.account) = trim(mnf.account)
) or
not exists (select 1
from "fccs".V_META_NOT_FOUND mnf
where trim(ff.entity) = mnf.trimc
) ;
Note: This answers the question as written. You might mean that both conditions are not met. In that case, use and instead of or.
table1 (id, name)
table2 (id, name)
Query:
SELECT name
FROM table2
-- that are not in table1 already
SELECT t1.name
FROM table1 t1
LEFT JOIN table2 t2 ON t2.name = t1.name
WHERE t2.name IS NULL
Q: What is happening here?
A: Conceptually, we select all rows from table1 and for each row we attempt to find a row in table2 with the same value for the name column. If there is no such row, we just leave the table2 portion of our result empty for that row. Then we constrain our selection by picking only those rows in the result where the matching row does not exist. Finally, We ignore all fields from our result except for the name column (the one we are sure that exists, from table1).
While it may not be the most performant method possible in all cases, it should work in basically every database engine ever that attempts to implement ANSI 92 SQL
You can either do
SELECT name
FROM table2
WHERE name NOT IN
(SELECT name
FROM table1)
or
SELECT name
FROM table2
WHERE NOT EXISTS
(SELECT *
FROM table1
WHERE table1.name = table2.name)
See this question for 3 techniques to accomplish this
I don't have enough rep points to vote up froadie's answer. But I have to disagree with the comments on Kris's answer. The following answer:
SELECT name
FROM table2
WHERE name NOT IN
(SELECT name
FROM table1)
Is FAR more efficient in practice. I don't know why, but I'm running it against 800k+ records and the difference is tremendous with the advantage given to the 2nd answer posted above. Just my $0.02.
SELECT <column_list>
FROM TABLEA a
LEFTJOIN TABLEB b
ON a.Key = b.Key
WHERE b.Key IS NULL;
https://www.cloudways.com/blog/how-to-join-two-tables-mysql/
This is pure set theory which you can achieve with the minus operation.
select id, name from table1
minus
select id, name from table2
Here's what worked best for me.
SELECT *
FROM #T1
EXCEPT
SELECT a.*
FROM #T1 a
JOIN #T2 b ON a.ID = b.ID
This was more than twice as fast as any other method I tried.
Watch out for pitfalls. If the field Name in Table1 contain Nulls you are in for surprises.
Better is:
SELECT name
FROM table2
WHERE name NOT IN
(SELECT ISNULL(name ,'')
FROM table1)
You can use EXCEPT in mssql or MINUS in oracle, they are identical according to :
http://blog.sqlauthority.com/2008/08/07/sql-server-except-clause-in-sql-server-is-similar-to-minus-clause-in-oracle/
That work sharp for me
SELECT *
FROM [dbo].[table1] t1
LEFT JOIN [dbo].[table2] t2 ON t1.[t1_ID] = t2.[t2_ID]
WHERE t2.[t2_ID] IS NULL
You can use following query structure :
SELECT t1.name FROM table1 t1 JOIN table2 t2 ON t2.fk_id != t1.id;
table1 :
id
name
1
Amit
2
Sagar
table2 :
id
fk_id
email
1
1
amit#ma.com
Output:
name
Sagar
All the above queries are incredibly slow on big tables. A change of strategy is needed. Here there is the code I used for a DB of mine, you can transliterate changing the fields and table names.
This is the strategy: you create two implicit temporary tables and make a union of them.
The first temporary table comes from a selection of all the rows of the first original table the fields of which you wanna control that are NOT present in the second original table.
The second implicit temporary table contains all the rows of the two original tables that have a match on identical values of the column/field you wanna control.
The result of the union is a table that has more than one row with the same control field value in case there is a match for that value on the two original tables (one coming from the first select, the second coming from the second select) and just one row with the control column value in case of the value of the first original table not matching any value of the second original table.
You group and count. When the count is 1 there is not match and, finally, you select just the rows with the count equal to 1.
Seems not elegant, but it is orders of magnitude faster than all the above solutions.
IMPORTANT NOTE: enable the INDEX on the columns to be checked.
SELECT name, source, id
FROM
(
SELECT name, "active_ingredients" as source, active_ingredients.id as id
FROM active_ingredients
UNION ALL
SELECT active_ingredients.name as name, "UNII_database" as source, temp_active_ingredients_aliases.id as id
FROM active_ingredients
INNER JOIN temp_active_ingredients_aliases ON temp_active_ingredients_aliases.alias_name = active_ingredients.name
) tbl
GROUP BY name
HAVING count(*) = 1
ORDER BY name
See query:
SELECT * FROM Table1 WHERE
id NOT IN (SELECT
e.id
FROM
Table1 e
INNER JOIN
Table2 s ON e.id = s.id);
Conceptually would be: Fetching the matching records in subquery and then in main query fetching the records which are not in subquery.
First define alias of table like t1 and t2.
After that get record of second table.
After that match that record using where condition:
SELECT name FROM table2 as t2
WHERE NOT EXISTS (SELECT * FROM table1 as t1 WHERE t1.name = t2.name)
I'm going to repost (since I'm not cool enough yet to comment) in the correct answer....in case anyone else thought it needed better explaining.
SELECT temp_table_1.name
FROM original_table_1 temp_table_1
LEFT JOIN original_table_2 temp_table_2 ON temp_table_2.name = temp_table_1.name
WHERE temp_table_2.name IS NULL
And I've seen syntax in FROM needing commas between table names in mySQL but in sqlLite it seemed to prefer the space.
The bottom line is when you use bad variable names it leaves questions. My variables should make more sense. And someone should explain why we need a comma or no comma.
I tried all solutions above but they did not work in my case. The following query worked for me.
SELECT NAME
FROM table_1
WHERE NAME NOT IN
(SELECT a.NAME
FROM table_1 AS a
LEFT JOIN table_2 AS b
ON a.NAME = b.NAME
WHERE any further condition);
How does SQLite internally treats the alias?
Does creating a table name alias internally creates a copy of the same table or does it just refers to the same table without creating a copy?
When I create multiple aliases of the same table in my code, performance of the query is severely hit!
In my case, I have one table, call it MainTable with namely 2 columns, name and value.
I want to select multiple values in one row as different columns. for example
Name: a,b,c,d,e,f
Value: p,q,r,s,t,u
such that a corresponds to p and so on.
I want to select values for names a,b,c and d in one row => p,q,r,s
So I write a query
SELECT t1.name, t2.name, t3.name, t4.name
FROM MainTable t1, MainTable t2, MainTable t3, MainTable t4
WHERE t1.name = 'a' and t2.name = 'b' and t3.name = 'c' and t4.name = 'd';
This way f writing the query kills the performance when size of the table increases as rightly pointed above by Larry.
Is there any efficient way to retrieve this result. I am bad at SQL queries :(
If you list the same table more than once in your SQL statement and do not supply conditions on which to JOIN the tables, you are creating a cartesian JOIN in your result set and it will be enormous:
SELECT * FROM MyTable A, MyTable B;
if MyTable has 1000 records, will create a result set with one million records. Any other selection criteria you include will then have to be evaluated across all one million records.
I'm not sure that's what you're doing (your question is very unclear), but it may be a start on solving your problem.
Updated answer now that the poster has added the query that is being executed.
You're going to have to get a little tricky to get the results you want. You need to use CASE and MAX and, unfortunately, the syntax for CASE is a little verbose:
SELECT MAX(CASE WHEN name='a' THEN value ELSE NULL END),
MAX(CASE WHEN name='b' THEN value ELSE NULL END),
MAX(CASE WHEN name='c' THEN value ELSE NULL END),
MAX(CASE WHEN name='d' THEN value ELSE NULL END)
FROM MainTable WHERE name IN ('a','b','c','d');
Please give that a try against your actual database and see what you get (of course, you want to make sure the column name is indexed).
Assuming you have table dbo.Customers with a million rows
SELECT * from dbo.Customers A
does not result in a copy of the table being created.
As Larry pointed out, the query as it stands is doing a cartesian product across your table four times which, as you has observed, kills your performance.
The updated ticket states the desire is to have 4 values from different queries in a single row. That's fairly simple, assuming this syntax is valid for sqllite
You can see that the following four queries when run in serial produce the desired value but in 4 rows.
SELECT t1.name
FROM MainTable t1
WHERE t1.name='a';
SELECT t2.name
FROM MainTable t2
WHERE t2.name='b';
SELECT t3.name
FROM MainTable t3
WHERE t3.name='c';
SELECT t4.name
FROM MainTable t4
WHERE t4.name='d';
The trick is to simply run them as sub queries like so there are 5 queries: 1 driver query, 4 sub's doing all the work. This pattern will only work if there is one row returned.
SELECT
(
SELECT t1.name
FROM MainTable t1
WHERE t1.name='a'
) AS t1_name
,
(
SELECT t2.name
FROM MainTable t2
WHERE t2.name='b'
) AS t2_name
,
(
SELECT t3.name
FROM MainTable t3
WHERE t3.name='c'
) AS t3_name
,
(
SELECT t4.name
FROM MainTable t4
WHERE t4.name='d'
) AS t4_name
Aliasing a table will result a reference to the original table that exists for the duration of the SQL statement.