I realized that i was using a varchar attribute as a index/key in a query, and that is killing my query performance. I am trying to look in my precienct table and get the integer ID, and then update my record in the household table with the new int FK, placed in a new column. this is the sql i have written thus far. but i am getting a
Error 1093 You can't specify target table 'voterfile_household' for update in FROM clause, and i am not sure how to fix it.
UPDATE voterfile_household
SET
PrecID = (SELECT voterfile_precienct.ID
FROM voterfile_precienct INNER JOIN voterfile_household
WHERE voterfile_precienct.PREC_ID = voterfile_household.Precnum);
Try:
update voterfile_household h, voterfile_precienct p
set h.PrecID = p.ID
where p.PREC_ID = h.Precnum
Take a look at update reference here.
Similarly, you can use inner join syntax as well.
update voterfile_household h inner join voterfile_precienct p on (h.Precnum = p.PREC_id)
set h.PrecID = p.ID
What if the subquery returns more than one result? That's why it doesn't work.
On SQL Server you can get this type of thing to work if the subquery does "SELECT TOP 1 ...", not sure if mysql will also accept it if you add a "limit 1" to the subquery.
I also think this is pretty much a duplicate of this question ("Can I have an inner SELECT inside of an SQL UPDATE?") from earlier today.
Firstly, your index on a varchar isn't always a bad thing, if it is not a key you can shrink how much of the field you index to only index say the first 10 chars or so.
Secondly, it won't let you do this as if it is a set that is returned it could break.
Related
I have this SQL query that has been working great. I would like to have something similar that would delete a line from PRC_FIX when the column DESCR in IM_ITEM begins with Clearance instead of where ITEM_VEND_NO = 'GAMES WORK'.
DELETE `PRC_FIX` FROM `PRC_FIX`
INNER JOIN `IM_ITEM` ON `IM_ITEM`.`ITEM_NO` = `PRC_FIX`.`ITEM_NO`
AND `IM_ITEM`.`ITEM_VEND_NO` = 'GAMES WORK'
Thanks for your help.
Edit: This was marked as a possible duplicate. I don't know that looking at the suggested duplicate would have helped me because I wouldn't have known how to implement it in this scenario involving 2 tables, but I'm willing to admit that might be my fault due to me being new to SQL.
You can use
DELETE PRC_FIX
FROM PRC_FIX
INNER JOIN IM_ITEM
ON IM_ITEM.ITEM_NO = PRC_FIX.ITEM_NO
WHERE UPPER(IM_ITEM.DESCR) LIKE 'CLEARANCE%';
You need to use the wildcard %.
in order to match with this string with different string which begins with "Clearance" you need to use "Clearance%".
Look here: SQL like search string starts with
You're fixed code:
DELETE `PRC_FIX` FROM `PRC_FIX`
INNER JOIN `IM_ITEM` ON `IM_ITEM`.`ITEM_NO` = `PRC_FIX`.`ITEM_NO`
AND IM_ITEM.DESCR LIKE 'Clearance%'
DETELE FROM PRC_FIX WHERE ITEM_NO IN (SELECT ITEM_NO FROM IM_ITEM WHERE ITEM_VEND_NO` = 'GAMES WORK')
EDIT OK so the main problem here was initial column1 FROM table1 with the join. Even that column1 has to be fully defined as table1.column1 even tho it is next to the FROM which seems at best odd to me. But I guess this is a newb error and I hope other newbs will find this useful.
//========================================================================
Have used simple joins before without problems. I thought the table.column format was unambiguous.
Warning is:
Integrity constraint violation: 1052 Column 'transmissionProgramID'
in field list is ambiguous'
The SQL is:
SELECT transmissionProgramID FROM transmissionProgramOwner
JOIN transmissionProgram on transmissionProgram.transmissionProgramID
= transmissionProgramOwner.transmissionProgramID WHERE
ownerType = '$ownerType' AND ownerID = '$ownerID' ORDER BY startDate
The two table transmissionProgramOwner and transmissionProgram both have fields called transmissionProgramID. I just cannot see how the table.column leaves anything ambiguous.
Sure it is something simple but I cannot see it. And I apologize for the long variable names but helps me keep things clear.
Additional info: Both transmissionProgramID are set to unique in both tables. I have tried every flaovor of JOIN but I think a simple join is allowed which just returns all records that match... In any case have tried every type of join just to make sure.
Friend try this
SELECT t1.transmissionProgramID FROM transmissionProgramOwner t1
JOIN transmissionProgram t2 on t2.transmissionProgramID
= t1.transmissionProgramID WHERE
t1.ownerType = '$ownerType' AND t1.ownerID = '$ownerID' ORDER BY t1.startDate;
change to
SELECT transmissionProgram.transmissionProgramID FROM
transmissionProgramOwner JOIN transmissionProgram on
'transmissionProgram.transmissionProgramID'
= 'transmissionProgramOwner.transmissionProgramID' WHERE ownerType = '$ownerType' AND ownerID = '$ownerID' ORDER BY startDate
I wanna write a query like this :
UPDATE `test_credit`
SET `test_credit`.`credit`=(`test_credit`.`credit`-((`test_credit`.`credit`/100)*5))
WHERE `test_credit`.`name` = `users`.`uname`
in fact i want to get a query on users.uname = test_credit.name but mysql say it has error and realize users.uname as column
what is correct query ?
You need to explicitly join it with table users. As far from my understanding based on your query, you want to calculate the credit if the names exists on both tables.
Give this a try,
UPDATE test_credit a
INNER JOIN users b
ON a.name = b.uname
SET a.credit = (a.credit - ((a.credit/100) * 5.0))
-- WHERE b.parent= "example"
I am bit stuck with this one.. what i want is update app_name (first table). It returns no error.. but does nothing...
UPDATE tbl_m_app AS tma, tbl_measure AS tm
SET tma.app_name='Ap1'
WHERE (tm.mesure_id = tma.mesure_id
AND tm.live = 1)
This query will do the same work in more obvious way and without joins
UPDATE tbl_m_app AS tma
SET tma.app_name='Ap1'
WHERE tma.mesure_id IN (SELECT tm.mesure_id FROM tbl_measure AS tm WHERE tm.live = 1)
I think this SQL is fine, it's just not matching any rows.
Check this by using a select with the same where clause:
SELECT * FROM tbl_measure tm WHERE tm.live=1;
0 rows returned, right?
I have two separate SELECT statements:
SELECT VCe.VId FROM `VCe` WHERE `YId` = 9007 AND `MaId` =76 AND `MoId` = 2851
SELECT r_pts.p_id FROM r_pts WHERE r_pts.v_id IN (57202, 57203, 69597, 82261, 82260, 69596, 69595, 82259)
When they are run separately they both complete in under .05sec however when I nest the first one within the second, it dramatically increases to 3.3sec.
I would like to do a join so that I can get the output from the second SELECT using the first select as the result set for the IN() but I cannot figure out how to include WHERE conditions in a JOIN.
Edit: Also what is the correct syntax to do a join as I am requesting?
Thanks for your help, its appreciated!
Equivalent to MattMcKnight's query whilst illustrating "how to include WHERE conditions in a JOIN":
SELECT r.p_id
FROM r_pts r
INNER JOIN VCe v
ON v.VId = r.v_id
AND
v.YId = 9007
AND
v.MaId = 76
AND
v.MoId = 2851
SELECT r_pts.p_id FROM r_pts, 'VCe' WHERE r_pts.v_id = VCe.VId AND VCe.YId = 9007 AND VCe.MaId =76 AND VCe.MoId = 2851
The basic goal of a join is to describe how the two tables relate. I inferred from your example that the v_id column in the r_pts table was a foreign key pointing to the VId primary key in the VCe table. When you add a term in the query (such as "r_pts.v_id = VCe.VId") that has a field from each table you wish to join, that tells the database how to match up the rows between the tables to make "virtual rows" that contain the columns from both tables. Your other query terms limit which rows are included in the result set.