I'd like to know how I check whether one or more of the elements (numbers in this case) in a string, eg. '1,2,3,5' are in another ,eg. '3,4,5,6'
3 and 5 are common elements to each string in that example.
In this case it is to create a SQL query based on the string comparisons.
One column value in a db contains one number string, and needs to be compared to another. I need results that match values of each string.
$results = $db->query("SELECT * FROM db
WHERE comparisonString IN (".$idsString.")
")->fetchAll (PDO::FETCH_ASSOC);
But its not quite working... it could be a lateral or syntactic answer.
MORE SPECIFICALLY, I am only getting a result when the FIRST element in the comaprisonString matches the other string elements.
Ideally the solution will look something like this:
$results = $db->query("SELECT * FROM db
WHERE ELEMENTS IN comparisonString IN (".$idsString.")
")->fetchAll (PDO::FETCH_ASSOC);
"ELEMENTS IN" is made up syntax, but that's the sort of thing I'm after
First of all it smells like a bad schema design. Don't store delimited strings of values in your database. Normalize your data by creating a many-to-many table. It will pay off big time enabling you to normally maintain and query your data.
In the meantime if you're using MySQL and assuming that your table looks something like
CREATE TABLE Table1
(
id int not null auto_increment primary key,
column_name varchar(128)
);
and let's say you have sample data
| ID | COLUMN_NAME |
|----|-------------|
| 1 | 3,4,5,6 |
| 2 | 4,6,22 |
| 3 | 7,5,11 |
| 4 | 9,12,1,3 |
| 5 | 8,32,16 |
and you want to select all rows where column_name contains one or more values from a list 1,2,3,5 you can do either
SELECT *
FROM table1
WHERE FIND_IN_SET(1, column_name) > 0
OR FIND_IN_SET(2, column_name) > 0
OR FIND_IN_SET(3, column_name) > 0
OR FIND_IN_SET(5, column_name) > 0
or
SELECT *
FROM table1 t JOIN
(
SELECT id
FROM table1 t JOIN
(
SELECT 1 value UNION ALL
SELECT 2 UNION ALL
SELECT 3 UNION ALL
SELECT 5
) s
ON FIND_IN_SET(s.value, t.column_name) > 0
GROUP BY id
) q
ON t.id = q.id
Output (in both cases):
| ID | COLUMN_NAME |
|----|-------------|
| 1 | 3,4,5,6 |
| 3 | 7,5,11 |
| 4 | 9,12,1,3 |
Here is SQLFiddle demo
Related
Consider a sample table with these rows:
+----+----------+-------+
| id | postcode | value |
+----+----------+-------+
| 1 | A1A3A3 | one |
| 2 | A1A3A4 | two |
| 3 | A1A3B | three |
| 4 | A1A3C | four |
| 5 | A1A3D | five |
| 6 | A1A3 | six |
| 7 | A1A | seven |
| 8 | A1 | eight |
+----+----------+-------+
My goal is to perform a query, whereby it steps down through the postcode column until an exact match is found.
Let's say my starting query parameter is A1A3E9. The expected return value, based on the sample table, would be six. It is important to note, that each step down, I remove one character from the end of the starting query parameter.
So first I would try and find a match for A1A3E9, and then A1A3E, and then A1A3 and so forth.
Currently, I achieve this simply with a series of IF/ELSE blocks, like this:
IF
EXISTS (
SELECT value FROM table
WHERE postcode=:userPost6_1
)
BEGIN
SELECT value FROM table
WHERE postcode=:userPost6_2
END
ELSE IF
EXISTS (
SELECT value FROM table
WHERE postcode=:userPost5_1
)
BEGIN
SELECT value FROM table
WHERE postcode=:userPost5_2
END
ELSE IF
EXISTS (
SELECT value FROM table
WHERE postcode=:userPost4_1
)
BEGIN
SELECT value FROM table
WHERE postcode=:userPost4_2
END
ELSE IF
EXISTS (
SELECT value FROM table
WHERE postcode=:userPost3_1
)
BEGIN
SELECT value FROM table
WHERE postcode=:userPost3_2
END
ELSE IF
EXISTS (
SELECT value FROM table
WHERE postcode=:userPost2_1
)
BEGIN
SELECT value FROM table
WHERE postcode=:userPost2_2
END
Note that I am using parameter binding in PHP, so just for context, my parameter bindings ultimately look like this:
$stmt->bindValue(':userPost6_1', "A1A3E9", PDO::PARAM_STR);
$stmt->bindValue(':userPost6_2', "A1A3E9", PDO::PARAM_STR);
$stmt->bindValue(':userPost5_1', "A1A3E", PDO::PARAM_STR);
$stmt->bindValue(':userPost5_2', "A1A3E", PDO::PARAM_STR);
$stmt->bindValue(':userPost4_1', "A1A3", PDO::PARAM_STR);
$stmt->bindValue(':userPost4_2', "A1A3", PDO::PARAM_STR);
$stmt->bindValue(':userPost3_1', "A1A", PDO::PARAM_STR);
$stmt->bindValue(':userPost3_2', "A1A", PDO::PARAM_STR);
$stmt->bindValue(':userPost2_1', "A1", PDO::PARAM_STR);
$stmt->bindValue(':userPost2_2', "A1", PDO::PARAM_STR);
I do not have have any concerns so far as performance is concerned, as I have an index on the postcode column (which contains 40,000+ rows). My concern is purely that this is visually, an unpleasant query to look at.
My question: Is there a cleaner way to write this query?
Here is one method:
select top (1) t.*
from t
where 'A1A3E9' like t.postcode + '%'
order by t.postcode desc;
The only issue is that your multiple if statements are probably faster. Getting performance is a real challenge with this type of problem. One method uses multiple joins:
select v.pc, coalesce(t0.value, t1.value, t2.value, . . . )
from (values ('A1A3E9')) v(pc) left join
t t0
on t0.postcode = v.pc left join
t t1
on t1.postcode = t0.postcode is null and
(case when len(v.pc) > 1 then left(v.pc, len(v.pc) - 1) end) left join
t t2
on t1.postcode is null and
t2.postcode = (case when len(v.pc) > 2 then left(v.pc, len(v.pc) - 2) end) left join
. . .
I would first spool all the potentially matching rows, eg:
select *
into #matches
from t
where postcode like 'AI%'
This can use an index on postcode and so should be cheap. Then whatever query you run against the matches will just operate over this subset. Even writing a UDF that compares postcode to a literal, eg:
select top 1 *
from #matches
order by dbo.NumberOfMatchingCharacters(postcode,'A1A3E9') desc
I have 2 different tables as want to get records in a single query. Currently, I am using 2 queries then merging the array result and then displaying the record. Following is my current code:
$db = JFactory::getDbo();
$query1 = "SELECT a.id as cId, a.title, a.parent_id,a.level FROM `categories` AS a WHERE ( a.title LIKE '%keyword%' )";
$result1 = $db->setQuery($query1)->loadObjectlist(); //gives selected records
$query2 = "SELECT b.id as indId, b.indicator , b.cat_id, b.subcat_id, b.section_id FROM `indicator` as b WHERE ( b.indicator LIKE '%keyword%' )";
$result2 = $db->setQuery($query2)->loadObjectlist(); //gives selected records
$_items = array_merge($result1,$result2); //then using $_items in php code to display the data
It is in Joomla however I just want to know how we can merge these 2 queries into one. I tried the following but it gives the result of first query from categories table.
(SELECT id as cId, title, parent_id,level, NULL FROM `categories` WHERE ( title LIKE '%birth%' ))
UNION ALL
(SELECT id as indId, indicator , cat_id, subcat_id, section_id FROM `indicator` WHERE ( indicator LIKE '%birth%' ))
Desired output:
+------+-------------+------------+--------+--------+----------------+--------+-----------+----------+
| cId | title | parent_id | level | indId | indicator | cat_id | subcat_id | section_id
+------+-------------+------------+--------+--------+----------------+--------+-----------+----------+
| 2874 | births | 2703 | 2 | null | null | null | null | null |
+------+-------------+------------+--------+--------+----------------+--------+-----------+----------+
| 13 | birth weight| 12 | 3 | null | null | null | null | null |
+------+-------------+------------+--------+--------+----------------+--------+-----------+----------+
| null | null | null | null | 135 | resident births| 23 | 25 | 1 |
+------+-------------+------------+--------+--------+----------------+--------+-----------+----------+
| null | null | null | null | 189 | births summary | 23 | 25 | 1 |
+------+-------------+------------+--------+--------+----------------+--------+-----------+----------+
This above output will help to get proper pagination records. I tried to use join but JOIN needs a common column in ON clause. Here, I want all the columns and their values. Basically I want to combine the 2 table records in one query. Any help would be appreciated
Here is an example,
There are a number of ways to do this, depending on what you really want. With no common columns, you need to decide whether you want to introduce a common column or get the product.
Let's say you have the two tables:
parts: custs:
+----+----------+ +-----+------+
| id | desc | | id | name |
+----+----------+ +-----+------+
| 1 | Sprocket | | 100 | Bob |
| 2 | Flange | | 101 | Paul |
+----+----------+ +-----+------+
Forget the actual columns since you'd most likely have a customer/order/part relationship in this case; I've just used those columns to illustrate the ways to do it.
A cartesian product will match every row in the first table with every row in the second:
> select * from parts, custs;
id desc id name
-- ---- --- ----
1 Sprocket 101 Bob
1 Sprocket 102 Paul
2 Flange 101 Bob
2 Flange 102 Paul
That's probably not what you want since 1000 parts and 100 customers would result in 100,000 rows with lots of duplicated information.
Alternatively, you can use a union to just output the data, though not side-by-side (you'll need to make sure column types are compatible between the two selects, either by making the table columns compatible or coercing them in the select):
> select id as pid, desc, '' as cid, '' as name from parts
union
select '' as pid, '' as desc, id as cid, name from custs;
pid desc cid name
--- ---- --- ----
101 Bob
102 Paul
1 Sprocket
2 Flange
In some databases, you can use a rowid/rownum column or pseudo-column to match records side-by-side, such as:
id desc id name
-- ---- --- ----
1 Sprocket 101 Bob
2 Flange 101 Bob
The code would be something like:
select a.id, a.desc, b.id, b.name
from parts a, custs b
where a.rownum = b.rownum;
It's still like a cartesian product but the where clause limits how the rows are combined to form the results (so not a cartesian product at all, really).
I haven't tested that SQL for this since it's one of the limitations of my DBMS of choice, and rightly so, I don't believe it's ever needed in a properly thought-out schema. Since SQL doesn't guarantee the order in which it produces data, the matching can change every time you do the query unless you have a specific relationship or order by clause.
I think the ideal thing to do would be to add a column to both tables specifying what the relationship is. If there's no real relationship, then you probably have no business in trying to put them side-by-side with SQL.
As #Sinto suggested the answer for union and dummy column names following is the whole correct query:
(SELECT id as cId, title, parent_id,level, NULL as indId, NULL as indicator , NULL as cat_id, NULL as subcat_id, NULL as section_id FROM `jm_categories` WHERE ( title LIKE '%births%' )) UNION ALL (SELECT NULL as cId, NULL as title, NULL as parent_id,NULL as level, id as indId, indicator , cat_id, subcat_id, section_id FROM `jm_indicator_setup` WHERE ( indicator LIKE '%births%' ))
We have to match the column names from both tables so that we get records as a combination.
I have a table like
+------+----------+
| id | location |
+------+----------+
| 1 | TVM |
| 2 | KLM |
| 3 | EKM |
+------+----------+
And I have an array of id like [1,2,1,3,1]. I need to get the result as
+------+----------+
| id | location |
+------+----------+
| 1 | TVM |
| 2 | KLM |
| 1 | TVM |
| 3 | EKM |
| 1 | TVM |
+------+----------+
I am already tried WHERE IN like conditions but no luck.
A where statement cannot multiply the number of rows. It can only filter rows out. You want a join:
select tl.*
from tablelike tl join
(select 1 as n union all select 2 union all select 1 union all
select 3 union all select 1
) n
on tl.id = n.n;
Note: if you are already generating the list via a query or from a table, then use that for the query rather than passing the list out of the database and then back in.
You could also return this result with a query like this; this uses a separate SELECT to return each occurrence of row with id=1.
( SELECT id, location FROM mytable WHERE id IN (1,2)
ORDER BY id
)
UNION ALL
( SELECT id, location FROM mytable WHERE id IN (1,3)
ORDER BY id
)
UNION ALL
( SELECT id, location FROM mytable WHERE id IN (1)
ORDER BY id
)
Following a similar pattern, the result could be obtained by combining the results from five SELECT statements, each returning a separate row. That would probably be a little simpler to achieve from a small array, e.g.
$glue = ") ) UNION ALL
(SELECT id, location FROM mytable WHERE id IN (";
$sql = "(SELECT id, location FROM mytable WHERE id IN ("
. implode($glue, $myarray)
. ") )";
I have the below table and I want to do the following:
Count the number of times each item appears in the table
Count the DISTINCT number of items
Group the items by name
+-------+---------+
| id | names |
+-------+---------+
| 1 | Apple |
| 2 | Orange |
| 3 | Grape |
| 4 | Apple |
| 5 | Apple |
| 6 | Orange |
| 7 | Apple |
| 8 | Grape |
+-------+---------+
For the 1. and 3. points I have the following query which works quite well:
SELECT * ,
COUNT(names) as count_name,
FROM tbl_products WHERE type = '1'
GROUP BY names
So I get:
Apple (4)
Orange (2)
Grape (2)
Now I want to also count the number of grouped by rows and added a line to count the distinct elements, however there is some problem, since MySQL accepts the query but cannot output a result:
SELECT * ,
COUNT(names) as count_name,
COUNT(DISTINCT names) as count_total
FROM tbl_products WHERE type = '1'
GROUP BY names
Can anyone advice what might be the problem?
EDIT: For more clearance I want to get a table like this:
+-------+---------+------------+-------------+
| id | names | count_ctg | count_total |
+-------+---------+------------+-------------+
| 1 | Apple | 4 | 3 |
| 2 | Orange | 2 | 3 |
| 3 | Grape | 2 | 3 |
+-------+---------+------------+-------------+
Why not just use the query you are using:
SELECT * ,
COUNT(names) as count_name,
FROM tbl_products WHERE type = '1'
GROUP BY names
This query achieves all three objectives.
1) You get a count of the number of each name value in count_name.
2) The number of distinct names values will be equal to the number of rows in the result set , since you are grouping by names. Pretty much any client-side MySQL DB connection library will enable you to retrieve this value.
3) You meet your third criteria of grouping by name by explictly using GROUP BY names
Of course the value for id in the result set is meaningless, you may want to only select names and count_names.
1-.Count the number of times each item appears in the table:
SELECT names, count(names) FROM tbl_products WHERE type = '1' group by names
2-. How many distinct items exist in the table:
SELECT DISTINCT names FROM tbl_products WHERE type = '1'
3-. Group the items by name:
SELECT count(DISTINCT names) as Total FROM tbl_products WHERE type = '1'
As your last EDIT (ALL IN ONE):
SELECT id, names, count(names), total FROM tbl_products, (select count(distinct names) as total from tbl_products) as total WHERE type = '1' group by names
You can get the count of distinct names in a subquery, then OUTER JOIN that thing back into your main query where you already solved for 1 and 3:
SELECT names ,
COUNT(names) as count_name,
Total
FROM tbl_products
OUTER JOIN (SELECT count(DISTINCT names) as Total FROM tbl_products) t2
WHERE type = '1'
GROUP BY names
You can use the SQL Windowing OVER()
This query returns the row_number() function as the id column in the results, and the over(...) for row_number requires an order by clause. You could order by whatever you want, but it most be ordered by something.
;WITH vwGroups (name, Quantity) AS
(
SELECT name
, COUNT(*)
FROM tbl_products
GROUP BY name
)
SELECT ROW_NUMBER() OVER(ORDER BY Quantity DESC, name) AS id
, name
, Quantity AS count_name
, COUNT(*) OVER () AS count_total
FROM vwGroups
I Have 2 Tables, One For New Pictures and One For New Users, i want to create like a wall that mixes the latest actions so it'll show new users & pictures ordered by date.
What i want is a single query and how to know inside the loop that the current entry is a photo or user.
TABLE: users
Columns: id,username,fullname,country,date
TABLE: photos
Columns: id,picurl,author,date
Desired Output:
Daniel from California Has just registred 5mins ago
New Picture By David ( click to view ) 15mins ago
And so on...
I'm begging you to not just give me the query syntax, i'm not pro and can't figure out how to deal with that inside the loop ( i only know how to fetch regular sql queries )
Thanks
You could use an union:
SELECT concat(username, " from ", country, " has just registered") txt, date FROM users
UNION
SELECT concat("New picture By ", username, " (click to view)") txt, date FROM photos INNER JOIN users ON author=users.id
ORDER BY date DESC
LIMIT 10
This assumes that author column in photos corresponds to the users table id. If author actually is a string containing the user name (which is a bad design), you'll have to do this instead:
SELECT concat(username, " from ", country, " has just registered") txt, date FROM users
UNION
SELECT concat("New picture By ", author, " (click to view)") txt, date FROM photos
ORDER BY date DESC
LIMIT 10
Make sure you have an index on date in both tables, or this will be very inefficient.
I've put together this little example for you to look at - you might find it helpful.
Full script can be found here : http://pastie.org/1279954
So it starts with 3 simple tables countries, users and user_photos.
Tables
Note: i've only included the minimum number of columns for this demo to work !
drop table if exists countries;
create table countries
(
country_id tinyint unsigned not null auto_increment primary key,
iso_code varchar(3) unique not null,
name varchar(255) unique not null
)
engine=innodb;
drop table if exists users;
create table users
(
user_id int unsigned not null auto_increment primary key,
country_id tinyint unsigned not null,
username varbinary(32) unique not null
-- all other detail omitted
)
engine=innodb;
drop table if exists user_photos;
create table user_photos
(
photo_id int unsigned not null auto_increment primary key,
user_id int unsigned not null,
-- all other detail omitted
key (user_id)
)
engine=innodb;
The important thing to note is that the primary keys of users and photos are unsigned integers and auto_increment (1,2,3..n) so I can find the latest 10 users and 10 photos by ordering by their primary keys (PK) descending and add a limit clause to restrict the number of rows returned.
-- change limit to increase rows returned
select * from users order by user_id desc limit 2;
select * from user_photos order by photo_id desc limit 2;
Test Data
insert into countries (iso_code, name) values ('GB','Great Britain'),('US','United States'),('DE','Germany');
insert into users (username, country_id) values ('f00',1),('bar',2),('stack',1),('overflow',3);
insert into user_photos (user_id) values (1),(1),(2),(3),(1),(4),(2),(1),(4),(2),(1);
So now we need a convenient way (single call) of selecting the latest 10 users and photos. The two tables are completely different so a union isnt going to be the best approach so what we'll do instead is write a stored procedure that returns two resultsets and handle generating the wall (merge resultsets) in our php script.
Stored procedure
Just a wrapper around some SQL code - think of it like SQL's version of a function call
drop procedure if exists list_latest_users_and_photos;
delimiter #
create procedure list_latest_users_and_photos()
begin
-- last 10 users
select
'U' as type_id, -- integer might be better
u.user_id,
u.country_id,
u.username,
-- other user columns...
c.name as country_name
from
users u
inner join countries c on u.country_id = c.country_id
order by
u.user_id desc limit 10;
-- last 10 photos
select
'P' as type_id,
up.photo_id,
up.user_id,
-- other photo columns...
u.username
-- other user columns...
from
user_photos up
inner join users u on up.user_id = u.user_id
order by
up.photo_id desc limit 10;
end #
delimiter ;
Testing
To test our stored procedure all we need to do is call it and look at the results.
mysql> call list_latest_users_and_photos();
+---------+---------+------------+----------+---------------+
| type_id | user_id | country_id | username | country_name |
+---------+---------+------------+----------+---------------+
| U | 4 | 3 | overflow | Germany |
| U | 3 | 1 | stack | Great Britain |
| U | 2 | 2 | bar | United States |
| U | 1 | 1 | f00 | Great Britain |
+---------+---------+------------+----------+---------------+
4 rows in set (0.00 sec)
+---------+----------+---------+----------+
| type_id | photo_id | user_id | username |
+---------+----------+---------+----------+
| P | 11 | 1 | f00 |
| P | 10 | 2 | bar |
| P | 9 | 4 | overflow |
| P | 8 | 1 | f00 |
| P | 7 | 2 | bar |
| P | 6 | 4 | overflow |
| P | 5 | 1 | f00 |
| P | 4 | 3 | stack |
| P | 3 | 2 | bar |
| P | 2 | 1 | f00 |
+---------+----------+---------+----------+
10 rows in set (0.01 sec)
Query OK, 0 rows affected (0.01 sec)
Now we know that works we can call it from php and generate the wall.
PHP Script
<?php
$conn = new Mysqli("localhost", "foo_dbo", "pass", "foo_db");
$result = $conn->query("call list_latest_users_and_photos()");
$users = array();
while($row = $result->fetch_assoc()) $users[] = $row;
$conn->next_result();
$result = $conn->use_result();
$photos = array();
while($row = $result->fetch_assoc()) $photos[] = $row;
$result->close();
$conn->close();
$wall = array_merge($users, $photos);
echo "<pre>", print_r($wall), "</pre>";
?>
Hope you find some of this helpful :)