In the database structured query language (SQL), the DELETE statement removes one or more records from a table.

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Cascade deletes from multiple tables

I have a fairly standard restaurant model with a restaurant table in a PostgreSQL DB. All restaurants have ratings (which consist of average, vote_count and vote_sum) but in order to avoid repeating ...
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146 views

Can having a LIMIT on DELETE degrade performance dramatically?

I have a database project in php and mysql. For, hopefully redundant, data security I added a LIMIT 1 to the delete($uniqueID) php function we use. Nobody cared because records really aren't ...
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Deleting a Row in Table- Best way to also delete all rows it affects? [closed]

I have created a very simple SQL script (see below) that deletes rows in my table if a column name is a certain value. DELETE FROM table_name WHERE some_column=some_value; However, this table ...
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MYSQL - FORCE INDEX ON A DELETE

UPDATE backup.records FORCE INDEX(IDX_records_deviceId) SET readyToBeDeleted = 1 WHERE deviceId = 226219 AND timestamp <= 1445255546 *** (1) WAITING FOR THIS LOCK TO BE GRANTED: RECORD LOCKS space ...
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110 views

Delete rows where matched value is twice as much

I'm trying to match two tables with two columns, table1 and table2. Each has id and price columns. I want the query to match each id and compare the price, then delete the row if the price in the ...
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DELETE command not completing on 30,000,000 row table

I have inherited a database and am looking to clean and speed it up. I have a table that contains 30,000,000 rows, many of which are junk data made by an error by our programmer. Before I add any new, ...
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532 views

Partialy Solved - Problems Deleting Data

I did a workaround that solved the problem for today but I want to know what I did wrong for the next project. I'm stuck on trying to delete some information on my MySQL database. I've never used a ...
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1answer
213 views

DELETE statement execution cancellation in SSMS

I ran a delete statement with wrong WHERE condition (which deletes all records from table instead of just 10 records) but during execution I found it and CANCELLED the execution in Management Studio, ...
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1answer
111 views

Hard delete vs soft delete performance

I've got this table that is intended to have a lot of activity. Anything that's in it indicates that a user action is still pending. Once deleted, it would indicate that action is no longer pending. ...
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156 views

Soft delete to improve performance: all wrong?

A few years back I read soft delete would improve performance of deletion, because instead of actually removing the item and impact the clustered (and all other) indices, it would just change a value. ...
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1answer
24 views

MySQL conditional trigger delete

I have a few tables (6 to be exact) and I want to make a trigger that will delete a row from a table based on a value from the main table. To elaborate, Let's say I have a main table called "main" ...
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1answer
24 views

Can I use table aliases in a MySQL DELETE statement?

This does not work: DELETE FROM topics AS t , posts AS p USING t INNER JOIN p WHERE t.id=p.topic_id AND t.id = '5599'; whereas this does: DELETE FROM topics, posts USING topics INNER JOIN posts ...
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Why “0 pages are entirely empty” after mass delete + vacuum?

I have a huge table for logging the user actions (audit log) in my PostgreSQL 9.4 database. It gets about 100 new records per second. I've removed very old records recently. I assume this affected a ...
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1answer
20 views

How to pass parameters to delete statement?

While executing this PL/SQL block: CREATE OR REPLACE PROCEDURE procAuth_Title_Delete (auth_ID NUMBER, title_Nos IN NUMBER) IS BEGIN DELETE FROM ...
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1answer
62 views

How to delete duplicate rows in merge replication

Somehow two rows in a table that is party to merge replication are identical, including their rowguid. I have no idea how this happened, it is only with two rows in my entire database (which is used ...
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1answer
18 views

Delete with join and condition (3 tables) - MySQL

Need some assistance on MySQL delete using join with condition (3 tables). snote (child table) -------- snote_id bnote_id bnote (parent table of snote) ------ bnote_id note_id note (parent table of ...
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1answer
36 views

Delete query does not appear to open space on the SQL Server

Our SQL Server (version 2012) is housed on a cloud server, for which we pay whenever we need additional space. We determined that we could delete some of the data to prevent the need for continually ...
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25 views

Changing Action on Delete to Cascade

We have a rather big database (about 400'000'000 records) in roughly 100 tables. The foreign keys in these tables are defined, so that No Action is taken, when deleting data from a table. We now have ...
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2answers
105 views

Help optimising delete statement

Using SQL Server 2012 Standard - I'm running a delete on a table based on the contents of another table. It's taking rather a long time (5 hours) and doesn't seem to be optimal to me, would appreciate ...
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1answer
33 views

Delete Query Issue in MySQL and PHPMyAdmin [closed]

I am facing a strange issue with MySQl. I am using PHP and MySQL to built an app. When I am trying to delete records from the table it runs successfully but no record is deleted from the database. ...
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69 views

Delete “Previous” row, if a value in a column in both rows are the same

Hi I'm new to SQL so bear with me. I am essentially trying to code a report that would give me the greatest number of concurrent events. For example, peak usage of phone calls. I have a column that ...
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0answers
34 views

Why is one table taking up ~75% of time for DELETE

I have a table (Period) linked to about 6-7 other tables. When I DELETE a period, a CASCADE DELETE is used to delete the related records in the other tables. Two of the tables (Result, Amount) have ...
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1answer
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Configure MariaDB to log row deletion ONLY

I'm investigating some rows/tables that intermittently go missing on a Magento site, and of course there's no entries in the error log. (I suspect Magento queries/rules or human error might be the ...
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Most efficient way of bulk deleting rows from postgres

I'm wondering what the most efficient way would be to delete large numbers of rows from PostgreSQL, this process would be part of a recurring task every day to bulk import data (a delta of insertions ...
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I need to run VACUUM FULL with no available disk space

I have one table that is taking up close to 90% of hd space on our server. I have decided to drop a few columns to free up space. But I need to return the space to the OS. The problem, though, is ...
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Oracle SQL script - passing a parameter

I have an Oracle SQL script like this: delete FROM activ_princ where id in (select ap.id FROM activ_princ ap inner join sect e on e.id=ap.FK_ID_SECTIUNE_e inner join chest ch on ...
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1answer
134 views

Alter ON DELETE CASCADE in 1 table

I'm really new to ON DELETE CASCADE. How can I delete child comments when the parent comment gets deleted in a table? Table Schema 'CREATE TABLE `comments` ( `id` int(11) NOT NULL AUTO_INCREMENT, ...
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2answers
121 views

what is the quickest way to delete duplicate rows?

I need to delete duplicate rows from a large table. what is the best way to achieve that? currently I use this algorithm: declare @t table ([key] int ) insert into @t select 1 insert into @t ...
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3answers
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How can a MySQL delete statement affect a table with over 30 millions records?

I have to delete about 28 million records from a InnoDB table in MySQL. I am wondering what happens if I am doing a select statement on the same table during the delete operation. I guess the delete ...
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1answer
448 views

Mysql foreign key cascade delete

Does mysql have a way to delete all sub links if a row was deleted from a "parent" table? Example table setup is below, the issue I am trying to avoid is having to maintain a script that deletes the ...
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Mysql - too many Deletion - Insertion

I'm creating cron jobs for my OLAP system. I have a cron job that deletes the records from the summary table first and then insert the records in it again: Say Deleting 1 month records, and ...
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1answer
50 views

Query optimization in case of TIMESTAMPDIFF

I have a table where I need to delete all rows older than 5 hours. Currently I'm doing: delete from my_table where TIMESTAMPDIFF(HOUR, from_unixtime(round(created_on/1000)), now()) > 5 The ...
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1answer
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Deleting large amounts of cascading records with minimal locking

I'm looking for a strategy to purge large amounts of logically deleted data from a MySQL database. The deleted records are in a relatively small table, but are referred to with many ON DELETE CASACDE ...
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Is it possible to cascade delete a column value? [duplicate]

So say I delete catID from table A and table B has the same foreign key value? It's hard to explain so I'll try and show you with the two images below: items table Is it possible to delete the ...
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1answer
2k views

DELETE from Linked Server table using OPENQUERY and dynamic criteria

I'm attempting to run a DELETE statement from my local SQL Server to delete appropriate records from a table in my remote linked server using OPENQUERY(). I'm using the following code, but it seems ...
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Which command Deletes and Frees Space

I'm reading through the 98-364 exam book and there's a question I can't quite answer: "What command would you use to remove all records from the Contact table that do not have a country of USA ...
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MySQL: Delete all but last N records

Consider the following table: mysql> DESCRIBE pixels; +---------------+-------------+------+-----+-------------------+----------------+ | Field | Type | Null | Key | Default ...
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3answers
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How to find out who deleted some data SQL Server

My boss had a query from a customer yesterday asking how they could find out who deleted some data in their SQL Server database (it is the express edition if that matters). I thought this could be ...
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1answer
781 views

Delete files from disk, with a job, respecting some rules ( SQL Server 2008 ) [closed]

We have An application that our customers use to download and upload files. I need to delete these files from disk after 30 days, of if it was downloded, in 7 days. How can i Use the script below, ...
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1answer
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Postgres 9.3 - deletes terribly slow for 10 minutes after dropping indexes/constraints

If I run a script which drops indexes (17 of them, CONCURRENTLY makes no difference except that without it I get the occasional deadlock), then constraints (20 constraints on 18 tables) and then run a ...
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3answers
398 views

Use “NOT IN” in the same table, Mysql

I have a table like that: table1 +----+------+--------------+ | id | name | phone_number | +----+------+--------------+ | 1 | A | 111111111111 | +----+------+--------------+ ...
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2answers
345 views

What is the best way to purge data from a table with minimum damage to performance?

When you purge records from a database table, deleting them, you have impact on the logical and physical structure of the target table, as well as indexes and statistics. What maintenance should be ...
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2answers
356 views

PostgreSQL : dependencies on a schema

I need to delete a schema in my PostgreSQL database. I would like to make sure that the schema is not used in another schema (for instance : this schema is used for a view in another one). Is there a ...
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3answers
39 views

To trigger or not to trigger- That is the question

I have a mysql table that tracks page views. Each row includes a date stamp. I want to remove all rows that are over 30 days old on a regular basis. Could, or should, I trigger an action on each ...
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2answers
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Why is truncate DDL?

I have an interview question, which was asked during my interview. I answered the question, but interviewer was not so convinced with my answer. So, anyone please correct me with my understanding ? ...
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2answers
87 views

how can I delete records when my disk drive is full?

My data folder of SQL as filled up the space of my local drive. I have 150KB free space left in the drive. So I have to delete some records to regain space. But when I run the delete query it says ...
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2answers
133 views

Should I stop an awfully inefficient MySQL DELETE statement?

I'm running the following statement on MySQL 5.5 in a 1GB 1CPU SSD virtual machine from Linode: DELETE table FROM ( SELECT MAX(id) id, field FROM table GROUP BY field ) temp_table INNER ...
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1answer
181 views

MySQL trigger after insert with insert and delete instructions does not work properly

I have the following trigger created in phpMyAdmin: Table: tb_agenda Time: AFTER Event: INSERT BEGIN INSERT INTO tb_realizacao (dt_agenda, titulo, ...
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305 views

SQL Server : trigger FOR DELETE

I want to create a trigger, which does not delete a customer if his name is Peter. How can I do that? CREATE TRIGGER trgCUSTOMER ON customer FOR DELETE AS BEGIN IF (SELECT name FROM deleted) not ...
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MySQL: delete…where..in( ) vs delete..from..join, and locked tables on delete with subselect

Disclaimer: please excuse my lack of knowledge about database internals. Here it goes: We run an application (not written by us) which has a big performance problem in a periodic cleanup job in the ...