I have two tables:
// table1 // table2
+----+------+---------+ +----+------+
| id | col1 | user_id | | id | col2 |
+----+------+---------+ +----+------+
| 1 | a | 100001 | | 1 | a |
| 2 | b | 100002 | | 2 | b |
| 3 | c | 100003 | | 3 | c |
+----+------+---------+ | 4 | a |
| 5 | a |
| 6 | c |
+----+------+
Also I have a variable named $user_id. Now I want to delete all row in the table2 where col2='a', But I need to check table1.user_id = $user_id (in this case $user_id = '100001' ) in the table1 before deleting.
How can I write a correct syntax query with this concept:
IF table1.user_id = $user_id where table1.col1 = 'a' then
delete from table2 where col2 = 'a'
I can do that using PHP and MySQL using two separated query. But I want to do that with one query, is it possible?
You can use JOIN to do the delete operation something as
delete t2 from table2 t2
join table1 t1 on t2.col2 = t1.col1
where
t2.col2 = 'a'
and t1.user_id = '100001'
Related
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
I have 3 table now:
First is : member_username
+-------------+------------------+
| uid | username |
+-------------+------------------+
| 1 | theone |
| 2 | ohno |
| 3 | prayforpr |
+-------------+------------------+
Second is : member_data
+-------------+-------------------+-----------------+
| uid | talk | etc |
+-------------+-------------------+-----------------+
| 1 | talk1 | |
| 2 | talkeee | |
| 3 | iojdfnl | |
+---------------------------------------------------+
Third is : member_level
+-------------+-------------------+-----------------+
| uid | level | fid |
+-------------+-------------------+-----------------+
| 1 | 2 | 1 |
| 1 | 10 | 2 |
| 2 | 1 | 1 |
| 2 | 99 | 2 |
| 1 | 40 | 3 |
| 3 | 50 | 1 |
| 1 | 44 | 4 |
+---------------------------------------------------+
I would like to query data and display the only one uid when member_level is higher in when SUM member_level.level Where fid in 1,2,3.
my query now is like below, but this query is sum all the level including fid 4 also, how to specify only sum in fid 1,2,3? and how do I assign the SUM of member_level.level Where fid in 1,2,3 to $levelKingTotalLevel?
$levelKing = DB::query("SELECT t1.uid,t1.username,t2.talk FROM ".DB::table('member_level')." t3 JOIN ".DB::table('member_username')." t1 ON(t3.uid = t1.uid) JOIN ".DB::table('member_data')." t2 ON (t1.uid = t2.uid) GROUP BY t3.uid ORDER BY SUM(t3.level) DESC LIMIT 1");
while($rowlevelKing = DB::fetch($levelKing)) {
$levelKingTotalLevel = $rowlevelKing['???'];
$levelKingN = $rowlevelKing['username'];
$levelKingUID = $rowlevelKing['uid'];
$levelKingT = $rowlevelKing['talk'];
};
echo "The ".$levelKingN." total level is ".$levelKingTotalLevel." and he talk about ".$levelKingT;
Thank you.
To filter records having fid values as 1, 2 or 3, use IN statement in WHERE clause. Alias totalLevel in select statement will give you total level for a user.
SELECT t1.uid, t1.username, t2.talk, SUM(t3.level) AS totalLevel
FROM member_level t3
JOIN member_username t1
ON (t3.uid = t1.uid)
JOIN member_data t2
ON (t1.uid = t2.uid)
WHERE t3.fid IN (1,2,3)
GROUP BY t3.uid
ORDER BY totalLevel DESC
LIMIT 1
I have 2 tables in database:
How can I get total user for each group. i.e: group 1: total are 2 users;
group2: total are 2 users;
group3: total is 1 user
You need normalization and never store comma-separated data.
Consider the following
mysql> select * from user_table ;
+---------+---------------+
| user_id | user_group_id |
+---------+---------------+
| 1 | 1,2 |
| 2 | 2 |
| 3 | 1,3 |
+---------+---------------+
3 rows in set (0.00 sec)
mysql> select * from group_table ;
+----------+------------+
| group_id | group_name |
+----------+------------+
| 1 | a |
| 2 | b |
| 3 | c |
+----------+------------+
3 rows in set (0.00 sec)
The above data is not normalized and to get the desired result out of these you need to use some in-efficient query as
select
g.group_id,
count(*) as total
from group_table g
left join user_table u on find_in_set(g.group_id,u.user_group_id) > 0
group by g.group_id ;
+----------+-------+
| group_id | total |
+----------+-------+
| 1 | 2 |
| 2 | 2 |
| 3 | 1 |
+----------+-------+
Now lets do normalization and store user-group data in a different table as
mysql> select * from user_to_group ;
+---------+----------+
| user_id | group_id |
+---------+----------+
| 1 | 1 |
| 1 | 2 |
| 2 | 2 |
| 3 | 1 |
| 3 | 3 |
+---------+----------+
You can easily write different queries from these tables now and here are some examples
select group_id,count(*) as tot from user_to_group group by group_id ;
+----------+-----+
| group_id | tot |
+----------+-----+
| 1 | 2 |
| 2 | 2 |
| 3 | 1 |
+----------+-----+
Joining the tables would even more easy
select
g.group_id,
g.group_name,
count(*) as tot
from user_to_group ug
join group_table g on g.group_id = ug.group_id
join user_table u on u.user_id = ug.user_id
group by g.group_id
+----------+------------+-----+
| group_id | group_name | tot |
+----------+------------+-----+
| 1 | a | 2 |
| 2 | b | 2 |
| 3 | c | 1 |
+----------+------------+-----+
SELECT group_name, COUNT(*) FROM user_table u, group_table g WHERE u.user_group_id LIKE %g.group_id% GROUP BY g.group_name;
this should work and give you a list of all groups and how many users are in them.
I will recommend you to create a third table which holds the information about which users are in which groups.
CREATE TABLE users_in_groups
(
user_id INT
, group_id INT
);
Then you can join like this:
SELECT
gt.group_id
, count(ut.user_id)
FROM
user_table AS ut
, INNER JOIN users_in_groups AS uig ON uig.user_id = ut.user_id
, INNER JOIN group_table AS gt ON gt.group_id = uig.group_id
GROUP BY
gt.group_id
;
To use the table you have now will you have to do something like this (in mysql):
SELECT
gt.group_id
, count(ut.user_id)
FROM
user_table AS ut
, INNER JOIN group_table AS gt ON LOCATE(gt.group_id, ut.user_group_id) > 0
GROUP BY
gt.group_id
Remember, when using group by, always locate what makes your group unique!
This is not an answer to your specific question but rather an alternative data structure proposal that might be better.
Introduce a new table members that looks like
# members
user_id | group_id
1 | 1
1 | 2
2 | 2
3 | 1
3 | 3
Then you could SELECT group_id, count(*) FROM members GROUP BY group_id
+----------+----------+
| group_id | count(*) |
+----------+----------+
| 1 | 2 |
| 2 | 2 |
| 3 | 1 |
+----------+----------+
This structure might also make it easier for you to manage your memberships. user_id + group_id should be unique. And if supported let them be foreign keys.
I have to do this with PHP on a simple SQLite database , with PDO
i have 3 table, tableA - tableB, TableC
tableA
the column TYPE represents the name of the other tables
___________________________________
|ID_OBJ | TYPE | PROP_1 | PROP_2 |
-----------------------------------
| 1000 | tableB | 0 | 10 |
| 1001 | tableB | 1 | 10 |
| 1002 | tableC | 1 | 10 |
-----------------------------------
tableB
____________________________
| ID | PROPA | PROPB |
----------------------------
| 1000 | ... | .... |
| 1001 | ... | .... |
----------------------------
tableC
____________________________
| ID | PROPAA | PROPBB |
----------------------------
| 1002 | ... | .... |
----------------------------
what I wanted to know is: Can i , through a JOIN (for example a LEFT JOIN) do a query that return something like this?
_______________________________________________________________________
|ID_OBJ | TYPE | PROP_1 | PROP_2 | PROPA | PROPB | PROPAA | PROPBB|
-----------------------------------------------------------------------
| 1000 | tableB | 0 | 10 | ... | ... | | |
| 1001 | tableB | 1 | 10 | ... | ... | | |
| 1002 | tableC | 1 | 10 | | | ... | ... |
-------------------------------------------------------------------------
I don't know how to do this, having to take the name of the table on which to perform a join from a table. So let me know if I can run a JOIN, and not having to do a query for each row present in the table tableA
thanks
An outer join also returns rows for which no match was found:
SELECT tableA.ID_OBJ,
tableA.TYPE,
tableA.PROP_1,
tableA.PROP_2,
tableB.PROPA,
tableB.PROPB,
tableC.PROPAA,
tableC.PROPBB
FROM tableA
LEFT JOIN tableB ON tableA.TYPE = 'tableB' AND tableA.ID_OBJ = tableB.ID
LEFT JOIN tableC ON tableA.TYPE = 'tableC' AND tableA.ID_OBJ = tableC.ID
If the are no 'wrong' rows in tableB/C, it is not necessary to check the type:
SELECT tableA.ID_OBJ,
tableA.TYPE,
tableA.PROP_1,
tableA.PROP_2,
tableB.PROPA,
tableB.PROPB,
tableC.PROPAA,
tableC.PROPBB
FROM tableA
LEFT JOIN tableB ON tableA.ID_OBJ = tableB.ID
LEFT JOIN tableC ON tableA.ID_OBJ = tableC.ID
How to delete all rows from a mysql table if values of two columns are equal
Example Table
invoice_id| item_id | name | invoiced_qty | received_qty
---------------------------------------------------------
| 1 | 1 | item1 | 3 | 2
| 2 | 2 | item2 | 5 | 5
| 3 | 1 | item3 | 4 | 3
| 4 | 2 | item4 | 2 | 2
| 5 | 1 | item5 | 5 | 5
After deleting table needs to retains
invoice_id| item_id | name | invoiced_qty | received_qty
---------------------------------------------------------
| 1 | 1 | item1 | 3 | 2
| 3 | 1 | item3 | 4 | 3
The select query which i created is
SELECT * FROM table1 A
INNER JOIN table1 B ON A.item_id = B.item_id
AND A.invoice_id = B.invoice_id
AND A.invoiced_qty = B.received_qty
Thanks
Why not just SQL Fiddle:
DELETE FROM table1
WHERE invoiced_qty = received_qty
Your edit does not change anything. He is the SQL Fiddle demonstrating your SELECT query. According to your sample data A.invoice_id will never equal B.invoice_id. So you will not get any results.
Try this :
DELETE FROM table1 A
INNER JOIN table1 B ON A.item_id = B.item_id
WHERE A.invoiced_qty = B.received_qty
You could simply wrap your select statement and select values to be deleted by id, like this:
DELETE FROM table1
WHERE item_id IN (SELECT item_id FROM table1 A
INNER JOIN table1 B ON A.item_id = B.item_id
AND A.invoice_id = B.invoice_id
AND A.invoiced_qty = B.received_qty)
however you should accept answer by Linger as it is more straightforward solution, mine was to indicate that if you have something selected usually you can wrap and delete.