i have two tables (table1 and table2) with common column customer_id, with union and few filters i am getting all the values from table 1 and table2. I need only rows where both the tables have the data based on the common column customer_id. Below is the example.
The output that I need is as follows
Here's what I've tried:
SELECT customer_id,
age,
amount,
type
FROM table1
WHERE age > 5
UNION
SELECT customer_id,
age,
amount,
type
FROM table2
WHERE age > 5
Your query combines the rows of the two tables but doesn't match customers present in both. What you need to add is the condition on the "customer_id" being present in the corresponding other table:
SELECT *
FROM table1
WHERE age > 5 AND customer_id IN (SELECT customer_id FROM table2)
UNION
SELECT *
FROM table2
WHERE age > 5 AND customer_id IN (SELECT customer_id FROM table1)
You should choose between:
UNION, if you want to return unique rows between the two tables - makes an additional aggregation operation
UNION ALL, if you want to allow repeated rows between the two tables
If you don't have repeated identical rows in your tables, then you should go with the most efficient one, which is UNION ALL.
I use mysql db engine, I wonder is it possible that the data in the table one row transferred to another table, this table would consist of two columns, id and value
each of the transferred value would go into one row and row would look like ID, value, and for as long as it has a value that is transferred to new row maintains the id as long as it has a value that belonged to the id of a row from which it transferred
Initial table looks like
id |country_name |city_1 |city_2 |city_3 |city_4
------------------------------------------------------------------------
1 |Some_country |some_city1 |some_city2 |some_city3 |some_city4
Wanted table looks like
id | city_name
1 | some_city1
1 | some_city2
1 | some_city3
1 | some_city4
Use this for one particular ID
select id, city_name from(
select id, city_1 as city_name from yourTable
union all
select id, city_2 from yourTable
union all
select id, city_3 from yourTable
union all
select id, city_4 from yourTable
) as t where id= yourID
http://sqlfiddle.com/#!9/7ee1f/1
Use this for whole table
select id, city_name from(
select id, city_1 as city_name from yourTable
union all
select id, city_2 from yourTable
union all
select id, city_3 from yourTable
union all
select id, city_4 from yourTable
) as t
order by id
What you are looking for is often referred to as vertical pivoting: you want to pivot something like an array of four city names - hard-wired into the table definition - into four vertical rows.
The solution is a cross join with a temporary table with as many consecutive integers, starting from 1, as you have columns to pivot, in conjunction with a CASE-WHEN expression that makes use of that series of integers.
See here:
WITH foo(id,country_name,city_1,city_2,city_3,city_4) AS (
SELECT 1,'Some_country','some_city1','some_city2','some_city3','some_city4'
)
, four_indexes(idx) AS (
SELECT 1
UNION ALL SELECT 2
UNION ALL SELECT 3
UNION ALL SELECT 4
)
SELECT
id AS country_id
, idx AS city_id
, CASE idx
WHEN 1 THEN city_1
WHEN 2 THEN city_2
WHEN 3 THEN city_3
WHEN 4 THEN city_4
ELSE ''
END AS city_name
FROM foo CROSS JOIN four_indexes
;
country_id|city_id|city_name
1| 1|some_city1
1| 3|some_city3
1| 2|some_city2
1| 4|some_city4
Only the other day, I answered a question that was looking for reversing the operation we are performing here: horizontal pivoting.
See here if you're curious ...
How to go about a column with different values in a same row in sql?
Happy Playing -
Marco the Sane
SELECT DISTINCT field1, field2, field3, ......
FROM table;
I am trying to accomplish the following SQL statement, but I want it to return all columns.
Is this possible?
Something like this:
SELECT DISTINCT field1, *
FROM table;
You're looking for a group by:
select *
from table
group by field1
Which can occasionally be written with a distinct on statement:
select distinct on field1 *
from table
On most platforms, however, neither of the above will work because the behavior on the other columns is unspecified. (The first works in MySQL, if that's what you're using.)
You could fetch the distinct fields and stick to picking a single arbitrary row each time.
On some platforms (e.g. PostgreSQL, Oracle, T-SQL) this can be done directly using window functions:
select *
from (
select *,
row_number() over (partition by field1 order by field2) as row_number
from table
) as rows
where row_number = 1
On others (MySQL, SQLite), you'll need to write subqueries that will make you join the entire table with itself (example), so not recommended.
From the phrasing of your question, I understand that you want to select the distinct values for a given field and for each such value to have all the other column values in the same row listed. Most DBMSs will not allow this with neither DISTINCT nor GROUP BY, because the result is not determined.
Think of it like this: if your field1 occurs more than once, what value of field2 will be listed (given that you have the same value for field1 in two rows but two distinct values of field2 in those two rows).
You can however use aggregate functions (explicitely for every field that you want to be shown) and using a GROUP BY instead of DISTINCT:
SELECT field1, MAX(field2), COUNT(field3), SUM(field4), ....
FROM table GROUP BY field1
If I understood your problem correctly, it's similar to one I just had. You want to be able limit the usability of DISTINCT to a specified field, rather than applying it to all the data.
If you use GROUP BY without an aggregate function, which ever field you GROUP BY will be your DISTINCT filed.
If you make your query:
SELECT * from table GROUP BY field1;
It will show all your results based on a single instance of field1.
For example, if you have a table with name, address and city. A single person has multiple addresses recorded, but you just want a single address for the person, you can query as follows:
SELECT * FROM persons GROUP BY name;
The result will be that only one instance of that name will appear with its address, and the other one will be omitted from the resulting table. Caution: if your fileds have atomic values such as firstName, lastName you want to group by both.
SELECT * FROM persons GROUP BY lastName, firstName;
because if two people have the same last name and you only group by lastName, one of those persons will be omitted from the results. You need to keep those things into consideration. Hope this helps.
That's a really good question. I have read some useful answers here already, but probably I can add a more precise explanation.
Reducing the number of query results with a GROUP BY statement is easy as long as you don't query additional information. Let's assume you got the following table 'locations'.
--country-- --city--
France Lyon
Poland Krakow
France Paris
France Marseille
Italy Milano
Now the query
SELECT country FROM locations
GROUP BY country
will result in:
--country--
France
Poland
Italy
However, the following query
SELECT country, city FROM locations
GROUP BY country
...throws an error in MS SQL, because how could your computer know which of the three French cities "Lyon", "Paris" or "Marseille" you want to read in the field to the right of "France"?
In order to correct the second query, you must add this information. One way to do this is to use the functions MAX() or MIN(), selecting the biggest or smallest value among all candidates. MAX() and MIN() are not only applicable to numeric values, but also compare the alphabetical order of string values.
SELECT country, MAX(city) FROM locations
GROUP BY country
will result in:
--country-- --city--
France Paris
Poland Krakow
Italy Milano
or:
SELECT country, MIN(city) FROM locations
GROUP BY country
will result in:
--country-- --city--
France Lyon
Poland Krakow
Italy Milano
These functions are a good solution as long as you are fine with selecting your value from the either ends of the alphabetical (or numeric) order. But what if this is not the case? Let us assume that you need a value with a certain characteristic, e.g. starting with the letter 'M'. Now things get complicated.
The only solution I could find so far is to put your whole query into a subquery, and to construct the additional column outside of it by hands:
SELECT
countrylist.*,
(SELECT TOP 1 city
FROM locations
WHERE
country = countrylist.country
AND city like 'M%'
)
FROM
(SELECT country FROM locations
GROUP BY country) countrylist
will result in:
--country-- --city--
France Marseille
Poland NULL
Italy Milano
SELECT c2.field1 ,
field2
FROM (SELECT DISTINCT
field1
FROM dbo.TABLE AS C
) AS c1
JOIN dbo.TABLE AS c2 ON c1.field1 = c2.field1
Great question #aryaxt -- you can tell it was a great question because you asked it 5 years ago and I stumbled upon it today trying to find the answer!
I just tried to edit the accepted answer to include this, but in case my edit does not make it in:
If your table was not that large, and assuming your primary key was an auto-incrementing integer you could do something like this:
SELECT
table.*
FROM table
--be able to take out dupes later
LEFT JOIN (
SELECT field, MAX(id) as id
FROM table
GROUP BY field
) as noDupes on noDupes.id = table.id
WHERE
//this will result in only the last instance being seen
noDupes.id is not NULL
Try
SELECT table.* FROM table
WHERE otherField = 'otherValue'
GROUP BY table.fieldWantedToBeDistinct
limit x
You can do it with a WITH clause.
For example:
WITH c AS (SELECT DISTINCT a, b, c FROM tableName)
SELECT * FROM tableName r, c WHERE c.rowid=r.rowid AND c.a=r.a AND c.b=r.b AND c.c=r.c
This also allows you to select only the rows selected in the WITH clauses query.
For SQL Server you can use the dense_rank and additional windowing functions to get all rows AND columns with duplicated values on specified columns. Here is an example...
with t as (
select col1 = 'a', col2 = 'b', col3 = 'c', other = 'r1' union all
select col1 = 'c', col2 = 'b', col3 = 'a', other = 'r2' union all
select col1 = 'a', col2 = 'b', col3 = 'c', other = 'r3' union all
select col1 = 'a', col2 = 'b', col3 = 'c', other = 'r4' union all
select col1 = 'c', col2 = 'b', col3 = 'a', other = 'r5' union all
select col1 = 'a', col2 = 'a', col3 = 'a', other = 'r6'
), tdr as (
select
*,
total_dr_rows = count(*) over(partition by dr)
from (
select
*,
dr = dense_rank() over(order by col1, col2, col3),
dr_rn = row_number() over(partition by col1, col2, col3 order by other)
from
t
) x
)
select * from tdr where total_dr_rows > 1
This is taking a row count for each distinct combination of col1, col2, and col3.
select min(table.id), table.column1
from table
group by table.column1
SELECT *
FROM tblname
GROUP BY duplicate_values
ORDER BY ex.VISITED_ON DESC
LIMIT 0 , 30
in ORDER BY i have just put example here, you can also add ID field in this
Found this elsewhere here but this is a simple solution that works:
WITH cte AS /* Declaring a new table named 'cte' to be a clone of your table */
(SELECT *, ROW_NUMBER() OVER (PARTITION BY id ORDER BY val1 DESC) AS rn
FROM MyTable /* Selecting only unique values based on the "id" field */
)
SELECT * /* Here you can specify several columns to retrieve */
FROM cte
WHERE rn = 1
In this way can get 2 unique column with 1 query only
select Distinct col1,col2 from '{path}' group by col1,col2
you can increase your columns if need
Add GROUP BY to field you want to check for duplicates
your query may look like
SELECT field1, field2, field3, ...... FROM table GROUP BY field1
field1 will be checked to exclude duplicate records
or you may query like
SELECT * FROM table GROUP BY field1
duplicate records of field1 are excluded from SELECT
Just include all of your fields in the GROUP BY clause.
It can be done by inner query
$query = "SELECT *
FROM (SELECT field
FROM table
ORDER BY id DESC) as rows
GROUP BY field";
SELECT * from table where field in (SELECT distinct field from table)
SELECT DISTINCT FIELD1, FIELD2, FIELD3 FROM TABLE1 works if the values of all three columns are unique in the table.
If, for example, you have multiple identical values for first name, but the last name and other information in the selected columns is different, the record will be included in the result set.
I would suggest using
SELECT * from table where field1 in
(
select distinct field1 from table
)
this way if you have the same value in field1 across multiple rows, all the records will be returned.
I had a problem in database. I have to insert duplicate records of a particular record on a another table based on a value.
First i used cursor to fetch each records and get the number of duplication i wants and after that used another cursor for duplication. Everything worked fine. But if the records in more than 500, i went dead slow. Then i did some research and found a way to insert without cursor.
INSERT INTO report(id, Name)
SELECT i.id,i.Name FROM (SELECT 1 AS id
UNION SELECT 2
UNION SELECT 3
UNION SELECT 4
UNION SELECT 5
UNION SELECT 6
UNION SELECT 7
UNION SELECT 8
UNION SELECT 9
UNION SELECT 10) AS o
INNER JOIN table i WHERE o.id<=i.frequence;
where frequence is the number of duplication. Please drop your idea to improve your query.
You could try creating a table with a record for each value from 1 to 10 and then join to that. I'm not sure it would be any faster though. You would have to experiment with it.
In this example the table with the values from 1 to 10 is called "dup" and the field containing these values is called "id".
INSERT INTO report(id, Name)
SELECT i.id, i.Name
FROM table i
JOIN dup d
ON d.id <= i.frequence;
If you have any table that contains a row number that goes at least as high as the maximum frequence, you could to this:
INSERT INTO report(id, Name)
SELECT i.id,i.Name FROM table i
inner join (
select distinct some_row_number_column from some_table
) o on o.some_row_number_column <= i.frequence;
This is basically the same as what you were doing, but it avoids the messy union all statements.
Or you could make a cursor that inserts numbers from 1 to the maximum frequence into a temporary table, then use that in your join. Or you could use a row numbering variable to generate the necessary sequence. Basically, do anything that will generate a list of consecutive numbers from 1 to the maximum that you need.
I would normally use recursion for this (DB2 syntax):
INSERT INTO report(id, Name)
with num_list (num) as (
values (1)
union all
select num + 1 from num_list
where num < (select max(frequence) from table)
)
SELECT i.id,i.Name FROM table i
inner join num_list on num_list.num <= i.frequence;
However, MySQL doesn't support recursion, apparently.
Given table 'x':
Source Dest Type
A B 2
A D 2
B C 2
Now I want the total count of Source and destination removing the matching ones..
Example of above one: For type 2, Count will be 4, i.e. Count(A,B,C,D)
I tried this:
select Count(distinct Source), Count(distinct destination),Count(distinct source)+Count( distinct destination),Type
from X
where Type=2 and Src NOT IN (select destination
from X
where Type=2)
I need to simplify this query for all the types.
Let me know if there is any way I could do it.
Thanks!
SELECT COUNT(DISTINCT a), Type
FROM (
SELECT DISTINCT Source AS a, Type
FROM x
UNION ALL
SELECT DISTINCT Dest AS a, Type
FROM x
)
GROUP By Type
The inner union query converts your two separate columns into a single column, then the outer query takes that union'd result and counts up the individual values, grouped by Type.
An inefficient method would be to do the following
SELECT
distinctMatches.type AS type,
COUNT(DISTINCT distinctMatches.name) AS quantity
FROM
(
(
SELECT DISTINCT
type,
source AS name
FROM x
)
UNION DISTINCT
(
SELECT DISTINCT
type,
destination AS name
FROM x
)
) AS distinctMatches
GROUP BY distinctMatches.type
This would give with your example data 1 row with type 2 and quantity 4
In an ideal world I'd look at the database design as it feels as if it should be split into multiple tables i.e. one for sources (as you seem to be grouping "source" and "destination" which indicates they are effectively the same item). If you are able to normalise the design further this type of query will be easier to do more efficiently
try this:
SELECT COUNT(xxx.a) as TotalCount
FROM
(SELECT source a, type FROM tableX
UNION
SELECT dest a, type FROM tableX) xxx
WHERE xxx.Type = 2