How to run this query without union operator? - mysql

I have a table that looks like this,
year,t1,t2,winner
I want to find the total appearances in the finals for a team, basically I need to union these two queries
select t1 from cups
union
select t2 from cups
and then do a group by. However, I would like to run this query without using UNION(not a homework) as I believe UNION is not standard SQL. I can't use IN as I will lose the counts. Does anybody have any suggestions?


You need to get two rows for each input row, one for t1 and one for t2. UNION is the proper and standard SQL way to do that. I can't even think of another vaguely sensible way to do it, and even those appear to scan the table twice.


You should use UNION ALL to include even the duplicates also.
Then count each team.
Query
select t.team,count(t.team) as `Total Appearances`
from
(
select team1 as team from tblMatches
union all
select team2 as team from tblMatches
)t
group by t.team;
SQL Fiddle


UNION Operator is reserved keyword in SQL
About SQL UNION Operator
The UNION operator is used to combine the result-set of two or more SELECT statements.
Notice that each SELECT statement within the UNION must have the same number of columns. The columns must also have similar data types. Also, the columns in each SELECT statement must be in the same order.
SQL UNION Syntax
SELECT column_name(s) FROM table1
UNION
SELECT column_name(s) FROM table2;
Same with Inner join
select t1
FROM cups
INNER JOIN cups2
ON t1.column_name=t2.column_name;
and you are finding two different fields in same table
select t1 from cups
union
select t2 from cups
so try this
SELECT *
FROM cups
WHERE t1=t2


If you are looking to find the team name and count of how many times that team has reached finals, something like this might be of help :
select team, count(1) as appearances from
( select t1 as team from cups
union all
select t2 as team from cups
) as totalAppearances
group by team

Related

How to duplicate returning values from a query in MySQL

When I use this I Get the table two times but I want each value duplicated before the next value comes
SELECT *
FROM student
WHERE major LIKE 'C%'
UNION ALL
SELECT *
FROM student
WHERE major LIKE 'C%';

You can use a union all. A union will not work, because it will eliminate duplicates. Another way is a cross join:
select
*
from
students t1 cross join
(select 1 as n union all select 2) n
WHERE major LIKE 'C%'
order by id;

Select the same columns from a list of tables

I am looking to run this query on a list of tables.
SELECT Description,Code,count(*) as count
FROM table1
group by Description,code
having count(*) > 1
I will have to run this query on 30+ different tables, I was wondering If I could change the from statement and just list off the table names.
In addition, is there some functionality that will add the name of the table that it came from in a seperate column to distinguish where the results came from?
Thanks in advance

You might use UNION ALL to put it together. Unless you need some dynamic table selection.
SELECT Description,Code,count(*) as count, 'table1' as tableNane
FROM table1
group by Description,code
having count(*) > 1
UNION ALL
SELECT Description,Code,count(*) as count, 'table2' as tableNane
FROM table2
group by Description,code
having count(*) > 1
...
Actualy I like #Shubhradeep Majumdar version. It will generate more concise code.
SELECT Description,Code, Count(Code), tableName FROM (
SELECT Description,Code, 'table1' as tableName
FROM table1
UNION ALL
SELECT Description,Code, 'table2' as tableName
FROM table2
) tables
GROUP BY tableName, Description, Code
HAVING COUNT(Code) > 1
But there might be a little catch to it. It is more elegant code, but it might actually be slower than first version. The problem is that tableName is appended at every record before grouping while in my first version you do that on already processed data.

Carrying over from #Marek's answer, You could first append all the tables to a table with union all.
select *, 'tab1' as tabnm from tab1
union all
select *, 'tab2' as tabnm from tab2
union all
select *, 'tab3' as tabnm from tab3
-- and so on...
And then use your code to process that final table.
will save you a great deal of time.
EDITED with a column specifying the table name

Mysql Union in different columns

I have the following query
SELECT *
FROM(
(SELECT
MAX(c.start_time) as start_1
FROM
c1 c)
UNION ALL
(SELECT
MAX(cc.created_at) as ccmax
FROM
cc1)
) as t
I'd like to have the result in a table with 2 columns start_1 and cmax instead of the single column I get with all the different results listed.
How should I do it? I ended up in a subselect believing this would have done the job.

For the data to be in two columns you would have to use a sub select.
SELECT
MAX(c1.start_time) as start_1, (SELECT MAX(cc1.created_at) FROM cc1) as ccmax
FROM c1

Quick SELECT WHERE IN like with flag

I have a list of ids and need to check whether user with id is in DB or not in one SELECT. Like SELECT WHERE IN (). But SELECT WHERE IN () doesn't suit my needs, I need in one SELECT distinguish those ids that are in table, and those that are not, not using any loops like multiple SELECTS. Any ideas are welcome!

I'm not sure if this is what you need, but I guess you have table 1 which contains a lot of IDs, and you would like to see which ones occur in table 2 and which ones don't?
select T1.ID, count(*) 'Times of occurrences in T2'
from table 1 T1
left outer join table 2 T2
ON T1.ID = T2.ID
group by T1.ID

You should provide more details. Would it be a single query so a list could be hardcoded into query or you want to find general solution for any list of ids provided? How long is your list?
For single query and not very long list you can use union. On example:
SELECT some_value, EXISTS( SELECT 1 FROM tableName WHERE user_id = some_value )
UNION ALL
SELECT other_value, EXISTS( SELECT 1 FROM tableName WHERE user_id = other_value )
UNION ALL
SELECT other_value2, EXISTS( SELECT 1 FROM tableName WHERE user_id = other_value2 )
UNION ALL
.....
If your list of ids can vary and/or consists of thousands of records it is impossible. In list you have columnar layout and you want to change it to row-level results. In MsSQL there are PIVOT, UNPIVOT clauses which can do that. In MySQL such transformation without explicit unions are impossible.

Select from multiple tables without a join?

What is the easiest way to select data from two tables and rather than join them, have them appear as separate rows. Both tables have similar or matching fields and I want to run some aggregate function on them such as avg all the rows that occurred in the same month, from both tables.
for example I have two tables, one that is shows transactions from one system and another with transactions from a different system. Is there a way to grab all the transactions from both tables as separate rows? if table 1 had twenty records and table 2 have thirty records, I'd like there to be 50 rows on the return.

You could try something like this:
SELECT ...
FROM (
SELECT f1,f2,f3 FROM table1
UNION
SELECT f1,f2,f3 FROM table2
)
WHERE ...

You could try this notattion:
SELECT * from table1,table2
More complicated one :
SELECT table1.field1,table1.field2, table2.field3,table2.field8 from table1,table2 where table1.field2 = something and table2.field3 = somethingelse
Such queries are usually called "implicit JOINs" and Explicit vs implicit SQL joins asks how both compare. In some cases implicit query execution planning is identical to explicit JOINs.

The UNION ALL operator may be what you are looking for.
With this operator, you can concatenate the resultsets from multiple queries together, preserving all of the rows from each. Note that a UNION operator (without the ALL keyword) will eliminate any "duplicate" rows which exist in the resultset. The UNION ALL operator preserves all of the rows from each query (and will likely perform better since it doesn't have the overhead of performing the duplicate check and removal operation).
The number of columns and data type of each column must match in each of the queries. If one of the queries has more columns than the other, we sometimes include dummy expressions in the other query to make the columns and datatypes "match". Often, it's helpful to include an expression (an extra column) in the SELECT list of each query that returns a literal, to reveal which of the queries was the "source" of the row.
SELECT 'q1' AS source, a, b, c, d FROM t1 WHERE ...
UNION ALL
SELECT 'q2', t2.fee, t2.fi, t2.fo, 'fum' FROM t2 JOIN t3 ON ...
UNION ALL
SELECT 'q3', '1', '2', buckle, my_shoe FROM t4
You can wrap a query like this in a set of parenthesis, and use it as an inline view (or "derived table", in MySQL lingo), so that you can perform aggregate operations on all of the rows.
SELECT t.a
, SUM(t.b)
, AVG(t.c)
FROM (
SELECT 'q1' AS source, a, b, c, d FROM t1
UNION ALL
SELECT 'q2', t2.fee, t2.fi, t2.fo, 'fum' FROM t2
) t
GROUP BY t.a
ORDER BY t.a

If your question was this -- Select ename, dname FROM emp, dept without using joins..
Then, I would do this...
SELECT ename, (SELECT dname
FROM dept
WHERE dept.deptno=emp.deptno)dname
FROM EMP
Output:
ENAME DNAME
---------- --------------
SMITH RESEARCH
ALLEN SALES
WARD SALES
JONES RESEARCH
MARTIN SALES
BLAKE SALES
CLARK ACCOUNTING
SCOTT RESEARCH
KING ACCOUNTING
TURNER SALES
ADAMS RESEARCH
ENAME DNAME
---------- --------------
JAMES SALES
FORD RESEARCH
MILLER ACCOUNTING
14 rows selected.

You should try this
SELECT t1.*,t2.* FROM t1,t2

SELECT * from table1
UNION
SELECT * FROM table2

Union will fetch data by row not column,So If your are like me who is looking for fetching column data from two different table with no relation and without join.
In my case I am fetching state name and country name by id. Instead of writing two query you can do this way.
select
(
select s.state_name from state s where s.state_id=3
) statename,
(
select c.description from country c where c.id=5
) countryname
from dual;
where dual is a dummy table with single column--anything just require table to view

select 'test', (select name from employee where id=1) as name, (select name from address where id=2) as address ;

In this case we are assuming that we have two tables:
SMPPMsgLogand SMSService with common column serviceid:
SELECT sp.SMS,ss.CMD
FROM vas.SMPPMsgLog AS sp,vas.SMSService AS ss
WHERE sp.serviceid=5431
AND ss.ServiceID = 5431
AND Receiver ="232700000"
AND date(TimeStamp) <='2013-08-07'
AND date(TimeStamp) >='2013-08-06' \G;

you can try this works always for me
query="SELECT * from tableX,tableY,table8";