I was wondering if there is a way to do something like selecting all without ... some columns here
something like SELECT */column1,column2 , is there a way to do this ?
I just need to output something like
column1 , column2 ( from another table ) , here all other columns without column1 ( or something to make the select skip the first few columns)
EDIT:
The thing is that i need this to be dynamic , so i cant just select what i don't know. I never know how many columns there will be , i just know the 1st and the 2nd column
EDIT: here is a picture http://oi44.tinypic.com/xgdyiq.jpg
I don't need the second id column , just the last column like i have pointed.
Start building custom views, which are geared aorund saving developers time and encapsulating them from the database schema.
Oh, so select all but certain fields. You have two options.
One is a little slow.. Copy the table, drop the fields you don't want, then SELECT *
The other is to build the field list from a subquery to information_schema or something, then remove occurrences of 'field_i_dont_want' in that list.
SELECT ( SELECT THE TABLES YOU WANT AND CONCAT INTO ONE STRING ) FROM TABLE
If you need to combine records from multiple tables, you need to find a way to relate them together. Primary Keys, Foreign Keys, or anything common among this.
I will try to explain this with a sql similar to your problem.
SELECT table1.id, table2.name, table1.column3, table1.column4
FROM table1
INNER JOIN table2 On table2.commmonfield = table1.commonfield
If you have 'n' columns in your table as in Col1,Col2,Col3....Coln you can select whatever columns you want to select from the table.
SELECT Col1,Col2 FROM YOURTABLE;
You either select all columns (*) or especify the columns you want one by one. There is no way to select 'all but some'.
The SQL language lets you either select a wildcard set of columns or enumerated single columns from a singular table. However you can join a secondary table and get a wildcard there.
SELECT
a.col1,
b.*
FROM
table_a as a
JOIN table_b as b ON (a.col5 = b.col_1)
Related
I have what I believe to be a pretty unique use case. I would like to be able to runs a single SELECT statement on a database where I get one column from four tables. I need to run where clauses on each different table where I have one main clause that will be across each of the tables and I am not able to JOIN because the data in each column will be a different length and I don't want to have duplicate items.
I have an example of the Select statement below. Also I understand if this is not possible.
SELECT s.service_id, u.id AS "user_id", h.mac_address, l.id AS "location_id" FROM services s
LEFT JOIN db.av_product ap ON s.product_id = ap.id
WHERE s.customer_code LIKE 'test_customer'
AND u.customer_code LIKE 'test_customer'
AND h.customer_code LIKE 'test_customer'
AND l.customer_code LIKE 'test_customer'
AND s.parent_id IS NULL
AND s.active=0
AND ap.sku NOT REGEXP 'fakeregex'
AND l.active = "1"
AND h.hardware_id NOT IN ('44','45')
AND (u.support_user != 1 OR u.support_user IS NULL);
TIA!
You will need to use joins for your tables to make a single query OR you can try multiple queries merged with UNION keyword.
If you want to make a single query, have a look about SELECT DISTINCT or GROUP BY for handling duplicates.
wut up?
do you know what UNION is?
The UNION operator is used to combine the result-set of two or more SELECT statements.
but every SELECT statement within UNION must have the same number of columns; so there we got a problem.
you can handle it with WHERE operator so I won't get in to it.
anyway, UNION!
shall we?
SELECT column_name(s) FROM table1
UNION
SELECT column_name(s) FROM table2;
anyway; your solution is UNION, maybe not like what I wrote.
you can try this link too.
https://www.w3schools.com/mysql/mysql_union.asp
have a clean code
What I am trying to do is select each distinct column1 value from table1 and then select all the columns from those rows returned from the above. Is this possible at all?
What I have so far, however, nothing is returned:
SELECT * FROM (SELECT DISTINCT column1 FROM table1)
I've thought about putting a unique/distinct restriction in the where clause of the query:
SELECT * FROM table1 WHERE some_unique_determiner column1
Any ideas how I could go about achieving the desired output?
Ok so answering my own question. What I need to do was to group the data by column1, without use of a nested query. Many thanks to #VR46 for the help.
SELECT * FROM table1 GROUP BY column1
Returned all columns from each unique value from column1
In your next posts, it will be better if you post your table structures, input and desired out put so it will be easier for us to understand.
If I did understand, there is one of two options:
Either you have duplicates, and you want to eliminate them so your correct query should be
select distinct COLUMNa,COLUMNb,COLUMNc... ETC
which will drop duplicates(that the entire row is the same).
Or you want to eliminate rows that have the same column1 and it doesn't matter if all the rest is the same or not.
In that case, You need to tell us which one of the result you want to keep, The up to date one,the older, random ETC.. because right now its impossible to make you a query that selects all the columns after you distinct, since all the duplicates will return like this:
SELECT * FROM TABLE WHERE COLUMN1 IN(SELECT DISTINCT COLUMN1 FROM TABLE)
Which is a wrong query since it doesn't do anything.
This may sound like an odd question, but I'm curious to know if it's possible...
Is there a way to simulate MySQL records using inline data? For instance, if it is possible, I would expect it to work something like this:
SELECT inlinedata.*
FROM (
('Emily' AS name, 26 AS age),
('Paul' AS name, 56 AS age)
) AS inlinedata
ORDER BY age
Unfortunately MySQL does not support the standard values row-constructor for this kind of things, so you need to use a "dummy" select for each row and combine the rows using UNION ALL
SELECT *
FROM (
select 'Emily' AS name, 26 AS age
union all
select 'Paul', 56
) AS inlinedata
ORDER BY age
The UNION ALL serves two purposes
It preserves any duplicate you might have on purpose
It's a (tiny) bit faster than a plain UNION (because it does not check for duplicates)
No, not without making it complicated, but you can create a temporary table and query that instead. Temporary tables are deleted when the current client session terminates.
You can query them and insert data into them just like with other tables. When you create them, you have to use the TEMPORARY keyword, like so:
CREATE TEMPORARY TABLE ...
This way, you can also reuse the data for multiple queries if needed, no data gets stored, and all records that you query have the right structure (whereas the syntax you give in your example would create problems when you spell a column name wrong)...
with cte as (
select '2012-04-04' as student_dob, '%test1%' as student_pat
union all
select '2012-05-04', '%test2%'
union all
select '2012-07-04', '%test3%'
union all
select '2012-05-11', '%test-n%'
)
select *
from students s
inner join cte c
on s.student_dob = c.student_dob and s.student_name like c.student_pat
arguably that's not a lot more readable, but taking a lead from that, you can just store those in a table or go through temporary table, like Roy suggested.
Also it's not great idea to make a group by student id and select also something else like you did in 2nd query.
I have two large tables in a database. They both contain a column called "name". My goal is to locate rows that contain names that are in one database but not the other.
I'm guessing there will be a join statement and a where, but I cannot figure out how to use the two in tandem in order to create a successful query.
Suggestions?
SELECT * FROM TABLE_A WHERE NAME NOT IN
( SELECT NAME FROM TABLE_B )
EXISTS might be faster than IN, see Difference between EXISTS and IN in SQL?.
You can use EXISTS like this. It's useful to know both approaches since they are not exactly equal. You can swap the EXISTS quantifier for SOME, ALL or ANY. I think you can figure out what would happen :)
select * from a1 where not exists(select 1 from a2 where name=a1.name);
Note that they are not 100% equal! SQL has three-valued logic!
I have two tables.
I query like this:
SELECT * FROM (
Select requester_name,receiver_name from poem_authors_follow_requests as one
UNION
Select requester_name,receiver_name from poem_authors_friend_requests as two
) as u
where (LOWER(requester_name)=LOWER('user1') or LOWER(receiver_name)=LOWER('user1'))
I am using UNION because i want to get distinct values for each user if a user exists in the first table and in the second.
For example:
table1
nameofuser
peter
table2
nameofuser
peter
if peter is on either table i should get the name one time because it exists on both tables.
Still i get one row from first table and a second from table number two. What is wrong?
Any help appreciated.
There are two problems with your SQL:
(THis is not the question, but should be considered) by using WHERE over the UNION instead of the tables, you create a performance nightmare: MySQL will create a temporary table containing the UNION, then query it over the WHERE. Using a calculation on a field (LOWER(requester_name)) makes this even worse.
The reason you get two rows is, that UNION DISTINCT will only suppress real duplicates, so the tuple (someuser,peter) and the tuple (someotheruser, peter) will result in duplication.
Edit
To make (someuser, peter) a duplicate of (peter, someuser) you could use:
SELECT
IF(requester_name='peter', receiver_name, requester_name) AS otheruser
FROM
...
UNION
SELECT
IF(requester_name='peter', receiver_name, requester_name) AS otheruser
FROM
...
So you only select someuser which you already know : peter
You need the where clause on both selects:
select requester_name, receiver_name
from poem_authors_follow_requests
where LOWER(requester_name) = LOWER('user1') or LOWER(receiver_name) = LOWER('user1')
union
select requester_name, receiver_name
from poem_authors_friend_requests
where LOWER(requester_name) = LOWER('user1') or LOWER(receiver_name) = LOWER('user1')
The two queries are independent of each other, so you shouldn't try to connect them other than by union.
You can use UNION if you want to select rows one after the other from several tables or several sets of rows from a single table all as a single result set.
UNION is available as of MySQL 4.0. This section illustrates how to use it.
Suppose you have two tables that list prospective and actual customers, a third that lists vendors from whom you purchase supplies, and you want to create a single mailing list by merging names and addresses from all three tables. UNION provides a way to do this. Assume the three tables have the following contents:
http://w3webtutorial.blogspot.com/2013/11/union-in-mysql.html
You are doing the union before and then applying the where clause. So you would get a unique combination of "requester_name,receiver_name" and then the where clause would apply. Apply the where clause in each select...
Select requester_name,receiver_name from poem_authors_follow_requests
where (LOWER(requester_name)=LOWER('user1')
or LOWER(receiver_name)=LOWER('user1'))
UNION
Select requester_name,receiver_name from poem_authors_friend_requests
where (LOWER(requester_name)=LOWER('user1')
or LOWER(receiver_name)=LOWER('user1'))
In your where statement, reference the alias "u" for each field refence in your where statement.
So the beginning of your where statement would be like: where (LOWER(u.requester_name) = ...
This is simlar to the answer you can see in: WHERE statement after a UNION in SQL?
You should be able to use the INTERSECT keyword instead of doing a nested query on a UNION.
SELECT member_id, name FROM a
INTERSECT
SELECT member_id, name FROM b
can simply be rewritten to
SELECT a.member_id, a.name
FROM a INNER JOIN b
USING (member_id, name)
http://www.bitbybit.dk/carsten/blog/?p=71