I have a SQL table which looks like:
---------------------
| price |price_two |
---------------------
| 35.90 | 0 |
| 21.90 | 5 |
| 7.90 | 0 |
| 50.21 | 30.29 |
---------------------
And now I want to create a query in SQL which switches all values from price to price_two, where price_two is lower than price but NOT 0.
So, at the end I want this:
---------------------
| price |price_two |
---------------------
| 35.90 | 0 |
| 5 | 21.90 |
| 7.90 | 0 |
| 30.29 | 50.21 |
---------------------
Can I do that and if yes, how?
Greetings and Thank You!
Something like...
SQL Fiddle
UPDATE Price P
INNER JOIN Price P2
on P.Price = P2.Price
AND P2.Price_two = P.Price_two
AND P.Price_two < P.Price
AND P.Price_two != 0
SET P.Price = P2.Price_two,
P.Price_two = P2.Price;
We simply use a self join and use the 2nd table's data to update the first since we need to materialize the values and perform both updates at once or we lose the handle to original values!
Related
I have two tables and i'm like to query 2 tables to obtain a report.
POSITION
+-------------+---------------+
| position_id | position_name |
+-------------+---------------+
| 1 | E1P1 |
| 2 | E1P2 |
| 3 | E3P3 |
| 4 | E4P4 |
+-------------+---------------+
PEOPLE
+------------+-------------+--------------------+
| people_id | people_name | people_position_id |
+------------+-------------+--------------------+
| 1 | JOHN | 2 |
| 2 | MARK | 4 |
+------------+-------------+--------------------+
QUERY
SELECT position_id, position_name, people_name FROM position
RIGHT JOIN people ON people_position_id = position_id
When I use simple query I get only matched rows, ho to obtain all?
I'm like to obtain this result
+----+----------+--------+
| ID | POSITION | STATUS |
+----+----------+--------+
| 1 | E1P1 | Empty |
| 2 | E1P2 | JOHN |
| 3 | E3P3 | Empty |
| 4 | E4P4 | MARK |
+----+----------+--------+
I would use a left join here:
SELECT
po.position_id,
po.position_name,
COALESCE(pe.people_name, 'EMPTY') AS STATUS
FROM position po
LEFT JOIN people pe
ON po.position_id = pe.people_position_id;
By the way, the reason your current right join attempt is failing is that you have placed the people table on the right side of the join. This means that non matching position records would be discarded. Here is my answer above, rewritten using a right join:
SELECT
po.position_id,
po.position_name,
COALESCE(pe.people_name, 'EMPTY') AS STATUS
FROM people pe
RIGHT JOIN position po
ON po.position_id = pe.people_position_id;
Note carefully that the table order has switched. Most of the time, you will see people using left joins rather than right joins.
I have 1 master_table and 2 sub_tables. I want the join the 3 columns together (but the problem is the 2 sub_tables do not have any column that share the same value) and then SELECT * based on 2 different columns from the 2 sub_tables.
I've searched and tried many ways of coding, but couldn't find a solution.
SELECT *
FROM (master INNER JOIN sub_1 ON master.id=sub_1.id WHERE sub_1.column_1 = 'Y')
AND (master INNER JOIN sub_2 ON master.id=sub_2.id WHERE sub_2.column_2 = 'Y')
ORDER BY master.id
++++++++++++++++++++++++++++++++++++++++++++++++++
* Finally, solved. See the solution at the bottom of this post. *
++++++++++++++++++++++++++++++++++++++++++++++++++
===========
Edit: explain more about my data, problem and MySQL code
I have 3 tables stored in MySQL as follow
Master_table: regist
------------------------------------------
| reg_no | firstname | lastname | submit |
------------------------------------------
| 1 | first_A | last_A | N |
| 2 | first_B | last_B | A |
| 3 | first_C | last_C | P |
| 4 | first_D | last_D | P |
| 5 | first_E | last_E | A |
| 6 | first_F | last_F | N |
| 7 | first_G | last_G | N |
| 8 | first_H | last_H | A |
------------------------------------------
Sub_1: sub_A Sub_2: sub_P
------------------------------ ------------------------------
| reg_no | A_title | reply_A | | reg_no | P_title | reply_P |
------------------------------ ------------------------------
| 2 | 222 | Y | | 3 | 333 | N |
| 5 | 555 | N | | 4 | 444 | Y |
| 8 | 888 | Y | ------------------------------
------------------------------
I want to create a query that gives result like this
----------------------------------------------------------------------------------
| reg_no | firstname | lastname | submit | A_title | reply_A | P_title | reply_P |
----------------------------------------------------------------------------------
| 2 | first_B | last_B | A | 222 | Y | | |
| 8 | first_H | last_H | A | 888 | Y | | |
| 4 | first_D | last_D | P | | | 444 | Y |
----------------------------------------------------------------------------------
or
-----------------------------------------------------------
| reg_no | firstname | lastname | submit | title | reply |
-----------------------------------------------------------
| 2 | first_B | last_B | A | 222 | Y |
| 8 | first_H | last_H | A | 888 | Y |
| 4 | first_D | last_D | P | 444 | Y |
-----------------------------------------------------------
$sql = "SELECT *
FROM (regist INNER JOIN sub_A ON regist.reg_no = sub_A.reg_no WHERE sub_A.reply_A = 'Y')
AND (regist INNER JOIN sub_P ON regist.reg_no = sub_P.reg_no WHERE sub_P.reply_P = 'Y')
ORDER BY regist.reg_no";
Expected outcome:
ECHO personal data of all registrants who got reply as 'Y'
if($row['submit']=="A") $title = $row['A_title'];
elseif($row['submit']=="P") $title = $row['P_title'];
$result = mysql_query($sql) or die(mysql_error());
while($row = mysql_fetch_array($result))
{
echo $row['reg_no']." / ".$row['firstname']." ".$row['lastname']." / ".$title."<br>";
}
Problem: my SELECT code resulted in error. The code from #GMB and #Rogue didn't error, but echo give nothing.
If it is not possible to code a query as I want, I will just modify the column names (sub_1.reply_A and sub_2.reply_P) to be the same and change the input code in other webpages. However, it would be best if there is a way because I don't know whether the 'reply' columns were used somewhere else.
========================
Solution: a little modification from #Rogue code
SELECT *
FROM master
LEFT OUTER JOIN sub_1
ON master.id=sub_1.id
LEFT OUTER JOIN sub_2
ON master.id=sub_2.id
WHERE sub_1.column_1 = 'Y'
OR sub_2.column_2 = 'Y'
ORDER BY master.id
Do you just want simple JOINs between these 3 tables ?
SELECT m.*, s1.*, s2.*
FROM master m
INNER JOIN sub_1 s1 ON m.id=s1.id AND s1.column_1 = 'Y'
INNER JOIN sub_2 s2 ON m.id=s2.id AND s2.column_2 = 'Y'
ORDER BY m.id;
If you have master records that may not exist in both sub tables, you can switch to LEFT JOIN to avoid filtering them out.
Guidelines :
typical syntax is SELECT ... FROM table1 INNER JOIN table2 ON ... INNER JOIN table3 ON...
better put all conditions related to a JOINed table in the ON clause of the join rather than in the WHERE clause
avoid SELECT * : be specific about the columns you want to select
use table aliases to make the query easier to read
You're a little off syntactically:
SELECT *
FROM master
LEFT OUTER JOIN sub_1
ON master.id=sub_1.id
LEFT OUTER JOIN sub_2
ON master.id=sub_2.id
WHERE sub_1.column_1 = 'Y'
AND sub_2.column_2 = 'Y'
ORDER BY master.id
Personally I would recommend not using SELECT * and only grabbing the data you will need. As for determining what join to use, I like to link to CodingHorror's blog post in these times.
Edit: swapped INNER to LEFT OUTER, per OP's update
Currently we are using a custom CI library to generate PDF files from documents which exist as database records in our database.
Each document is related to the contents (== rows) with a one-has-many relation. Each row has a number (field: row_span) to indicate how many lines it will use once it gets printed in the PDF.
Per PDF page that gets build, Rows needed for that page only are selected using a subquery:
$where = $this->docType."_id = ".$this->data['doc']->id." AND visible = 1";
$sql = "SELECT *,
(SELECT
sum(row_span) FROM app_".$this->docType."_rows X
WHERE X.position <= O.position
AND ".$where."
ORDER BY position ASC) 'span_total'
FROM app_".$this->docType."_rows O
WHERE ".$where."
HAVING span_total > ".(($i-1)*$this->maxRows)." AND span_total <= ".($i*$this->maxRows)." ORDER BY O.position ASC ";
$rows = $rows->query($sql);
In the code $i is the page number and $this->maxRows is loaded from the document template record which indicates how many available lines the PDF template has.
So when the SQL renders it might look like this for page 1 of an order with ID 834:
SELECT `app_order_rows`.*,
(SELECT SUM(`app_order_rows_subquery`.`row_span`) AS row_span
FROM `app_order_rows` `app_order_rows_subquery`
WHERE `app_order_rows_subquery`.`position` <= 'app_order_rows.position'
AND `app_order_rows_subquery`.`order_id` = 834
AND `app_order_rows_subquery`.`visible` = 1
ORDER BY `app_order_rows_subquery`.`position` asc) AS span_total
FROM (`app_order_rows`)
WHERE `app_order_rows`.`order_id` = 834
AND `app_order_rows`.`visible` = 1
HAVING span_total > 0
AND span_total <= 45
ORDER BY `app_order_rows`.`position` asc
And running this with EXPLAIN gives this as output:
+====+=============+=========================+======+===============+======+=========+======+======+=============================+===+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | |
+====+=============+=========================+======+===============+======+=========+======+======+=============================+===+
| 1 | PRIMARY | app_order_rows | ALL | NULL | NULL | NULL | NULL | 1809 | Using where; Using filesort | 1 |
+----+-------------+-------------------------+------+---------------+------+---------+------+------+-----------------------------+---+
| 2 | SUBQUERY | app_order_rows_subquery | ALL | NULL | NULL | NULL | NULL | 1809 | Using where | 2 |
+====+=============+=========================+======+===============+======+=========+======+======+=============================+===+
This is working great, but... When we have large orders or invoices it renders the documents very slow. This might be due to the subquery.
Does anyone have an idea on how to do the same select without subquery? Maybe we will have to go for a whole new approach to select rows and build the PDF. We are open for suggestions ^^
Thanks in advance
------------------------------- edit ------------------------------
The EXPLAIN after index creation:
+====+=============+=========================+=======+===============+============+=========+=======+======+=============+===+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | |
+====+=============+=========================+=======+===============+============+=========+=======+======+=============+===+
| 1 | PRIMARY | app_order_rows | ref | index_main | index_main | 5 | const | 9 | Using where | 1 |
+----+-------------+-------------------------+-------+---------------+------------+---------+-------+------+-------------+---+
| 2 | SUBQUERY | app_order_rows_subquery | range | index_main | index_main | 10 | NULL | 1 | Using where | 2 |
+====+=============+=========================+=======+===============+============+=========+=======+======+=============+===+
As you confirmed in the comments, the tables have no indexes.
The immediate solution would be:
create index index_main on app_order_rows (order_id, position);
I have three tables group_sentences, group_sentences_attributes and group_senteces_categories.
I have an attributes array which I am using in query with IN (after implode).
Then I have one category ID because they are stored recursively, so no need for an array.
I need to select one group number where is the biggest match for $attributesArray and of course category too.
Here is table group_sentences_attributes
+-----+-------+-----------+
| id | group | attribute |
+-----+-------+-----------+
| 1 | 1 | 3564 |
| 2 | 1 | 3687 |
| 3 | 1 | 3689 |
| 4 | 2 | 3687 |
| 5 | 2 | 3564 |
+-----+-------+-----------+
Here is group_sentences_category
+-----+-------+----------+
| id | group | category |
+-----+-------+----------+
| 1 | 1 | 1564 |
| 2 | 1 | 1221 |
| 3 | 1 | 1756 |
| 4 | 2 | 1358 |
| 5 | 2 | 1125 |
+-----+-------+----------+
Here is my query, but I am afraid that it won't do the job done.
SELECT group_categories.group
FROM group_categories, group_attributes
WHERE group_categories.category = '$category'
AND group_attributes.attribute IN ($attributesArray)
GROUP BY group_categories.group
ORDER BY count(group_attributes.attribute)
Any help would be appreciated, thanks.
First, the table in your query do not match the tables in the question. I am guessing they are simply missing the "sentence". Then, you have no join clause. Simple rule: Never use commas in the from clause.
group is a lousy name for a column, because it is a keyword in SQL. The following may be what you are looking for:
SELECT gc.groupid
FROM group_sentences_attributes sa JOIN
group_sentences_category sc
ON sa.groupid = sc.groupid
WHERE sc.category = '$category' AND
sa.attribute IN ($attributesArray)
GROUP BY sa.groupid
ORDER BY count(sa.attribute);
If you only want one row, then add LIMIT 1 to the end.
I have a table of Products that looks like so:
| id | Description | Price |
| 1 | dinglehopper | 2.99 |
| 2 | flux capacitor | 48.99 |
| 3 | thing1 | 48.99 |
And so on...
Then I have an OrderLineItem table which, as you can guess, links each item in an order to the product:
| id | productID | OrderID |
| 43 | 1 | 12 |
| 44 | 2 | 12 |
| 52 | 3 | 15 |
So, as you can see, order #12 contains a dinglehopper and flux capacitor. How can I get this information in a single query? I just want ALL the products associated with a given OrderID in the OrderLineItem table.
May be by
select p.description,p.id,o.irderId
from
`orderLineItem` o, `product` p
where
p.id = o.productId;
or
select p.description,p.id,o.irderId
from `orderLineItem` o
join `product` p
on p.id = o.productId;
LEFT JOIN :)
http://www.w3schools.com/sql/sql_join_left.asp
#Pete About "single" query part, you should make VIEW from this join, if really going to use a lot.