Related
I know that you can insert multiple rows at once, is there a way to update multiple rows at once (as in, in one query) in MySQL?
Edit:
For example I have the following
Name id Col1 Col2
Row1 1 6 1
Row2 2 2 3
Row3 3 9 5
Row4 4 16 8
I want to combine all the following Updates into one query
UPDATE table SET Col1 = 1 WHERE id = 1;
UPDATE table SET Col1 = 2 WHERE id = 2;
UPDATE table SET Col2 = 3 WHERE id = 3;
UPDATE table SET Col1 = 10 WHERE id = 4;
UPDATE table SET Col2 = 12 WHERE id = 4;
Yes, that's possible - you can use INSERT ... ON DUPLICATE KEY UPDATE.
Using your example:
INSERT INTO table (id,Col1,Col2) VALUES (1,1,1),(2,2,3),(3,9,3),(4,10,12)
ON DUPLICATE KEY UPDATE Col1=VALUES(Col1),Col2=VALUES(Col2);
Since you have dynamic values, you need to use an IF or CASE for the columns to be updated. It gets kinda ugly, but it should work.
Using your example, you could do it like:
UPDATE table SET Col1 = CASE id
WHEN 1 THEN 1
WHEN 2 THEN 2
WHEN 4 THEN 10
ELSE Col1
END,
Col2 = CASE id
WHEN 3 THEN 3
WHEN 4 THEN 12
ELSE Col2
END
WHERE id IN (1, 2, 3, 4);
The question is old, yet I'd like to extend the topic with another answer.
My point is, the easiest way to achieve it is just to wrap multiple queries with a transaction. The accepted answer INSERT ... ON DUPLICATE KEY UPDATE is a nice hack, but one should be aware of its drawbacks and limitations:
As being said, if you happen to launch the query with rows whose primary keys don't exist in the table, the query inserts new "half-baked" records. Probably it's not what you want
If you have a table with a not null field without default value and don't want to touch this field in the query, you'll get "Field 'fieldname' doesn't have a default value" MySQL warning even if you don't insert a single row at all. It will get you into trouble, if you decide to be strict and turn mysql warnings into runtime exceptions in your app.
I made some performance tests for three of suggested variants, including the INSERT ... ON DUPLICATE KEY UPDATE variant, a variant with "case / when / then" clause and a naive approach with transaction. You may get the python code and results here. The overall conclusion is that the variant with case statement turns out to be twice as fast as two other variants, but it's quite hard to write correct and injection-safe code for it, so I personally stick to the simplest approach: using transactions.
Edit: Findings of Dakusan prove that my performance estimations are not quite valid. Please see this answer for another, more elaborate research.
Not sure why another useful option is not yet mentioned:
UPDATE my_table m
JOIN (
SELECT 1 as id, 10 as _col1, 20 as _col2
UNION ALL
SELECT 2, 5, 10
UNION ALL
SELECT 3, 15, 30
) vals ON m.id = vals.id
SET col1 = _col1, col2 = _col2;
All of the following applies to InnoDB.
I feel knowing the speeds of the 3 different methods is important.
There are 3 methods:
INSERT: INSERT with ON DUPLICATE KEY UPDATE
TRANSACTION: Where you do an update for each record within a transaction
CASE: In which you a case/when for each different record within an UPDATE
I just tested this, and the INSERT method was 6.7x faster for me than the TRANSACTION method. I tried on a set of both 3,000 and 30,000 rows.
The TRANSACTION method still has to run each individually query, which takes time, though it batches the results in memory, or something, while executing. The TRANSACTION method is also pretty expensive in both replication and query logs.
Even worse, the CASE method was 41.1x slower than the INSERT method w/ 30,000 records (6.1x slower than TRANSACTION). And 75x slower in MyISAM. INSERT and CASE methods broke even at ~1,000 records. Even at 100 records, the CASE method is BARELY faster.
So in general, I feel the INSERT method is both best and easiest to use. The queries are smaller and easier to read and only take up 1 query of action. This applies to both InnoDB and MyISAM.
Bonus stuff:
The solution for the INSERT non-default-field problem is to temporarily turn off the relevant SQL modes: SET SESSION sql_mode=REPLACE(REPLACE(##SESSION.sql_mode,"STRICT_TRANS_TABLES",""),"STRICT_ALL_TABLES",""). Make sure to save the sql_mode first if you plan on reverting it.
As for other comments I've seen that say the auto_increment goes up using the INSERT method, this does seem to be the case in InnoDB, but not MyISAM.
Code to run the tests is as follows. It also outputs .SQL files to remove php interpreter overhead
<?php
//Variables
$NumRows=30000;
//These 2 functions need to be filled in
function InitSQL()
{
}
function RunSQLQuery($Q)
{
}
//Run the 3 tests
InitSQL();
for($i=0;$i<3;$i++)
RunTest($i, $NumRows);
function RunTest($TestNum, $NumRows)
{
$TheQueries=Array();
$DoQuery=function($Query) use (&$TheQueries)
{
RunSQLQuery($Query);
$TheQueries[]=$Query;
};
$TableName='Test';
$DoQuery('DROP TABLE IF EXISTS '.$TableName);
$DoQuery('CREATE TABLE '.$TableName.' (i1 int NOT NULL AUTO_INCREMENT, i2 int NOT NULL, primary key (i1)) ENGINE=InnoDB');
$DoQuery('INSERT INTO '.$TableName.' (i2) VALUES ('.implode('), (', range(2, $NumRows+1)).')');
if($TestNum==0)
{
$TestName='Transaction';
$Start=microtime(true);
$DoQuery('START TRANSACTION');
for($i=1;$i<=$NumRows;$i++)
$DoQuery('UPDATE '.$TableName.' SET i2='.(($i+5)*1000).' WHERE i1='.$i);
$DoQuery('COMMIT');
}
if($TestNum==1)
{
$TestName='Insert';
$Query=Array();
for($i=1;$i<=$NumRows;$i++)
$Query[]=sprintf("(%d,%d)", $i, (($i+5)*1000));
$Start=microtime(true);
$DoQuery('INSERT INTO '.$TableName.' VALUES '.implode(', ', $Query).' ON DUPLICATE KEY UPDATE i2=VALUES(i2)');
}
if($TestNum==2)
{
$TestName='Case';
$Query=Array();
for($i=1;$i<=$NumRows;$i++)
$Query[]=sprintf('WHEN %d THEN %d', $i, (($i+5)*1000));
$Start=microtime(true);
$DoQuery("UPDATE $TableName SET i2=CASE i1\n".implode("\n", $Query)."\nEND\nWHERE i1 IN (".implode(',', range(1, $NumRows)).')');
}
print "$TestName: ".(microtime(true)-$Start)."<br>\n";
file_put_contents("./$TestName.sql", implode(";\n", $TheQueries).';');
}
UPDATE table1, table2 SET table1.col1='value', table2.col1='value' WHERE table1.col3='567' AND table2.col6='567'
This should work for ya.
There is a reference in the MySQL manual for multiple tables.
Use a temporary table
// Reorder items
function update_items_tempdb(&$items)
{
shuffle($items);
$table_name = uniqid('tmp_test_');
$sql = "CREATE TEMPORARY TABLE `$table_name` ("
." `id` int(10) unsigned NOT NULL AUTO_INCREMENT"
.", `position` int(10) unsigned NOT NULL"
.", PRIMARY KEY (`id`)"
.") ENGINE = MEMORY";
query($sql);
$i = 0;
$sql = '';
foreach ($items as &$item)
{
$item->position = $i++;
$sql .= ($sql ? ', ' : '')."({$item->id}, {$item->position})";
}
if ($sql)
{
query("INSERT INTO `$table_name` (id, position) VALUES $sql");
$sql = "UPDATE `test`, `$table_name` SET `test`.position = `$table_name`.position"
." WHERE `$table_name`.id = `test`.id";
query($sql);
}
query("DROP TABLE `$table_name`");
}
Why does no one mention multiple statements in one query?
In php, you use multi_query method of mysqli instance.
From the php manual
MySQL optionally allows having multiple statements in one statement string. Sending multiple statements at once reduces client-server round trips but requires special handling.
Here is the result comparing to other 3 methods in update 30,000 raw. Code can be found here which is based on answer from #Dakusan
Transaction: 5.5194580554962
Insert: 0.20669293403625
Case: 16.474853992462
Multi: 0.0412278175354
As you can see, multiple statements query is more efficient than the highest answer.
If you get error message like this:
PHP Warning: Error while sending SET_OPTION packet
You may need to increase the max_allowed_packet in mysql config file which in my machine is /etc/mysql/my.cnf and then restart mysqld.
There is a setting you can alter called 'multi statement' that disables MySQL's 'safety mechanism' implemented to prevent (more than one) injection command. Typical to MySQL's 'brilliant' implementation, it also prevents user from doing efficient queries.
Here (http://dev.mysql.com/doc/refman/5.1/en/mysql-set-server-option.html) is some info on the C implementation of the setting.
If you're using PHP, you can use mysqli to do multi statements (I think php has shipped with mysqli for a while now)
$con = new mysqli('localhost','user1','password','my_database');
$query = "Update MyTable SET col1='some value' WHERE id=1 LIMIT 1;";
$query .= "UPDATE MyTable SET col1='other value' WHERE id=2 LIMIT 1;";
//etc
$con->multi_query($query);
$con->close();
Hope that helps.
You can alias the same table to give you the id's you want to insert by (if you are doing a row-by-row update:
UPDATE table1 tab1, table1 tab2 -- alias references the same table
SET
col1 = 1
,col2 = 2
. . .
WHERE
tab1.id = tab2.id;
Additionally, It should seem obvious that you can also update from other tables as well. In this case, the update doubles as a "SELECT" statement, giving you the data from the table you are specifying. You are explicitly stating in your query the update values so, the second table is unaffected.
You may also be interested in using joins on updates, which is possible as well.
Update someTable Set someValue = 4 From someTable s Inner Join anotherTable a on s.id = a.id Where a.id = 4
-- Only updates someValue in someTable who has a foreign key on anotherTable with a value of 4.
Edit: If the values you are updating aren't coming from somewhere else in the database, you'll need to issue multiple update queries.
No-one has yet mentioned what for me would be a much easier way to do this - Use a SQL editor that allows you to execute multiple individual queries. This screenshot is from Sequel Ace, I'd assume that Sequel Pro and probably other editors have similar functionality. (This of course assumes you only need to run this as a one-off thing rather than as an integrated part of your app/site).
And now the easy way
update my_table m, -- let create a temp table with populated values
(select 1 as id, 20 as value union -- this part will be generated
select 2 as id, 30 as value union -- using a backend code
-- for loop
select N as id, X as value
) t
set m.value = t.value where t.id=m.id -- now update by join - quick
Yes ..it is possible using INSERT ON DUPLICATE KEY UPDATE sql statement..
syntax:
INSERT INTO table_name (a,b,c) VALUES (1,2,3),(4,5,6)
ON DUPLICATE KEY UPDATE a=VALUES(a),b=VALUES(b),c=VALUES(c)
use
REPLACE INTO`table` VALUES (`id`,`col1`,`col2`) VALUES
(1,6,1),(2,2,3),(3,9,5),(4,16,8);
Please note:
id has to be a primary unique key
if you use foreign keys to
reference the table, REPLACE deletes then inserts, so this might
cause an error
I took the answer from #newtover and extended it using the new json_table function in MySql 8. This allows you to create a stored procedure to handle the workload rather than building your own SQL text in code:
drop table if exists `test`;
create table `test` (
`Id` int,
`Number` int,
PRIMARY KEY (`Id`)
);
insert into test (Id, Number) values (1, 1), (2, 2);
DROP procedure IF EXISTS `Test`;
DELIMITER $$
CREATE PROCEDURE `Test`(
p_json json
)
BEGIN
update test s
join json_table(p_json, '$[*]' columns(`id` int path '$.id', `number` int path '$.number')) v
on s.Id=v.id set s.Number=v.number;
END$$
DELIMITER ;
call `Test`('[{"id": 1, "number": 10}, {"id": 2, "number": 20}]');
select * from test;
drop table if exists `test`;
It's a few ms slower than pure SQL but I'm happy to take the hit rather than generate the sql text in code. Not sure how performant it is with huge recordsets (the JSON object has a max size of 1Gb) but I use it all the time when updating 10k rows at a time.
The following will update all rows in one table
Update Table Set
Column1 = 'New Value'
The next one will update all rows where the value of Column2 is more than 5
Update Table Set
Column1 = 'New Value'
Where
Column2 > 5
There is all Unkwntech's example of updating more than one table
UPDATE table1, table2 SET
table1.col1 = 'value',
table2.col1 = 'value'
WHERE
table1.col3 = '567'
AND table2.col6='567'
UPDATE tableName SET col1='000' WHERE id='3' OR id='5'
This should achieve what you'r looking for. Just add more id's. I have tested it.
UPDATE `your_table` SET
`something` = IF(`id`="1","new_value1",`something`), `smth2` = IF(`id`="1", "nv1",`smth2`),
`something` = IF(`id`="2","new_value2",`something`), `smth2` = IF(`id`="2", "nv2",`smth2`),
`something` = IF(`id`="4","new_value3",`something`), `smth2` = IF(`id`="4", "nv3",`smth2`),
`something` = IF(`id`="6","new_value4",`something`), `smth2` = IF(`id`="6", "nv4",`smth2`),
`something` = IF(`id`="3","new_value5",`something`), `smth2` = IF(`id`="3", "nv5",`smth2`),
`something` = IF(`id`="5","new_value6",`something`), `smth2` = IF(`id`="5", "nv6",`smth2`)
// You just building it in php like
$q = 'UPDATE `your_table` SET ';
foreach($data as $dat){
$q .= '
`something` = IF(`id`="'.$dat->id.'","'.$dat->value.'",`something`),
`smth2` = IF(`id`="'.$dat->id.'", "'.$dat->value2.'",`smth2`),';
}
$q = substr($q,0,-1);
So you can update hole table with one query
I have a MySQL table like this,
id (primary key) | name | scores
and I am reading a large file to insert records into the MySQL table.
New records will be added into this file but the old records are not deleted, so when I read the file, a lot of records are already in the database.
Except to use SELECT COUNT to see if a record is already in the database, is there a best way to check it (to save processing time & database load)?
Or maybe I should just INSERT it directly? (The database will not allow records with duplicate id anyway.)
I usually use update + insert method.
first i will run the update statement. the update query will act like a select query + directly update the data.
update t1 set t1.Name = 'Name', t1.Scores = 99
where t1.Name = 'Name' and t1.Scores = 99
then check if there is a row affected by the above query. if not run the insert statement
if ##RowCount = 0
insert into t1 (Name, Scores) values ('Name',99)
Serch examples for
INSERT IGNORE INTO table
Simple example for this is
INSERT IGNORE INTO `transcripts`
SET `ensembl_transcript_id` = ‘ENSORGT00000000001′,
`transcript_chrom_start` = 12345
`transcript_chrom_end` = 12678;
Which of those operations should perform faster in MySQL? Presume I have 999 values to change:
DELETE FROM table WHERE id IN(100, ..., 999);
INSERT INTO example VALUES (100, 'Peter'), (...), (999, 'Sam');
OR
UPDATE table_name SET name='Peter'
WHERE person_id=100; ...; UPDATE table_name SET name='Sam' WHERE person_id=999;
Since you have only 900 row values to change then first option will perform fast. Because you will have only two queries to run. But if you go for second option then you will have almost 900 queries to run that will definitely slow. And more better idea to do same would be
TRUNCATE FROM table;
INSERT INTO example VALUES (100, 'Peter'), (...), (999, 'Sam');
because truncate works faster than delete.
In the general case, those two operations (DELETE/INSERT vs UPDATE) could have significantly different results, based on the current state of the table... Does row with id=999 exist? Are there foreign key constraints that reference this table? Are there any triggers defined on the table?
If the specification is to update rows in a table, I would issue an UPDATE statement, rather than issuing a DELETE and INSERT.
There are factors beyond speed to consider.
But fastest would likely be:
UPDATE example t
SET t.name
= CASE t.id
WHEN 100 THEN 'Peter'
WHEN ...
WHEN 999 THEN 'Sam'
ELSE t.name
END
WHERE t.id IN (100,...999)
I have two tables, one having a many-to-many relationship (fooBarTable with columns fooId and barId) and another InnoDB table fooCounterTable with columns fooId and counter counting the occurences of fooId in fooBarTable.
When deleting all barId's from fooBarTable, I need to update the fooCounterTable accordingly.
The first thing I tried was this:
UPDATE fooCounterTable SET counter = counter - 1
WHERE fooId IN (SELECT fooId FROM fooBarTable WHERE barId = 42 ORDER BY fooId);
But I got this error:
MySQL error (1205): Lock wait timeout exceeded; try restarting transaction
Updating the table when adding barId's is working fine with this SQL statement:
INSERT INTO `fooCounterTable` (fooId, counter) VALUES (42,1), (100,1), (123,1)
ON DUPLICATE KEY UPDATE counter = counter + 1;
So I thought I'd do the same thing when decreasing the counter, even if it looks stupid to insert 0-Values, which should never happen:
INSERT INTO `fooCounterTable` (SELECT fooId, 0 FROM fooBarTable WHERE barId = 42 ORDER BY fooId)
ON DUPLICATE KEY UPDATE counter = counter - 1;'
This seems to work fine in most cases, but sometimes I get a deadlock:
MySQL error (1213): Deadlock found when trying to get lock; try restarting transaction
So I read about deadlocks and found out about SELECT ... FOR UPDATE and I tried this:
START TRANSACTION;
SELECT fooId FROM fooCounterTable
WHERE fooId IN (SELECT fooId FROM fooBarTable WHERE barId = 42 ORDER BY fooId) FOR UPDATE;
UPDATE fooCounterTable SET counter = counter - 1
WHERE fooId IN (SELECT fooId FROM fooBarTable WHERE barId = 42 ORDER BY fooId);
COMMIT;
which resulted in:
MySQL error (2014): commands out of sync
Can anyone tell me how to resolve my problem?
Update
The last error (2014) occured, because I did not use and free the SELECT statement's results before executing the UPDATE statement, which is mandatory. I fixed that and I got rid of error 2014, but I still have deadlocks (error 1205) from time to time and I don't understand, why.
Do you know what fooID you have just deleted when firing this query?
If so seems like this would work...
UPDATE fooCounterTable SET counter =
(SELECT count(*) FROM fooBarTable WHERE fooId = 42)
WHERE fooID = 42
I wonder if you really need that counter table tho. If your indexes are set up properly there shouldn't be too much of a speed penalty to a more normalized approach.
I know that you can insert multiple rows at once, is there a way to update multiple rows at once (as in, in one query) in MySQL?
Edit:
For example I have the following
Name id Col1 Col2
Row1 1 6 1
Row2 2 2 3
Row3 3 9 5
Row4 4 16 8
I want to combine all the following Updates into one query
UPDATE table SET Col1 = 1 WHERE id = 1;
UPDATE table SET Col1 = 2 WHERE id = 2;
UPDATE table SET Col2 = 3 WHERE id = 3;
UPDATE table SET Col1 = 10 WHERE id = 4;
UPDATE table SET Col2 = 12 WHERE id = 4;
Yes, that's possible - you can use INSERT ... ON DUPLICATE KEY UPDATE.
Using your example:
INSERT INTO table (id,Col1,Col2) VALUES (1,1,1),(2,2,3),(3,9,3),(4,10,12)
ON DUPLICATE KEY UPDATE Col1=VALUES(Col1),Col2=VALUES(Col2);
Since you have dynamic values, you need to use an IF or CASE for the columns to be updated. It gets kinda ugly, but it should work.
Using your example, you could do it like:
UPDATE table SET Col1 = CASE id
WHEN 1 THEN 1
WHEN 2 THEN 2
WHEN 4 THEN 10
ELSE Col1
END,
Col2 = CASE id
WHEN 3 THEN 3
WHEN 4 THEN 12
ELSE Col2
END
WHERE id IN (1, 2, 3, 4);
The question is old, yet I'd like to extend the topic with another answer.
My point is, the easiest way to achieve it is just to wrap multiple queries with a transaction. The accepted answer INSERT ... ON DUPLICATE KEY UPDATE is a nice hack, but one should be aware of its drawbacks and limitations:
As being said, if you happen to launch the query with rows whose primary keys don't exist in the table, the query inserts new "half-baked" records. Probably it's not what you want
If you have a table with a not null field without default value and don't want to touch this field in the query, you'll get "Field 'fieldname' doesn't have a default value" MySQL warning even if you don't insert a single row at all. It will get you into trouble, if you decide to be strict and turn mysql warnings into runtime exceptions in your app.
I made some performance tests for three of suggested variants, including the INSERT ... ON DUPLICATE KEY UPDATE variant, a variant with "case / when / then" clause and a naive approach with transaction. You may get the python code and results here. The overall conclusion is that the variant with case statement turns out to be twice as fast as two other variants, but it's quite hard to write correct and injection-safe code for it, so I personally stick to the simplest approach: using transactions.
Edit: Findings of Dakusan prove that my performance estimations are not quite valid. Please see this answer for another, more elaborate research.
Not sure why another useful option is not yet mentioned:
UPDATE my_table m
JOIN (
SELECT 1 as id, 10 as _col1, 20 as _col2
UNION ALL
SELECT 2, 5, 10
UNION ALL
SELECT 3, 15, 30
) vals ON m.id = vals.id
SET col1 = _col1, col2 = _col2;
All of the following applies to InnoDB.
I feel knowing the speeds of the 3 different methods is important.
There are 3 methods:
INSERT: INSERT with ON DUPLICATE KEY UPDATE
TRANSACTION: Where you do an update for each record within a transaction
CASE: In which you a case/when for each different record within an UPDATE
I just tested this, and the INSERT method was 6.7x faster for me than the TRANSACTION method. I tried on a set of both 3,000 and 30,000 rows.
The TRANSACTION method still has to run each individually query, which takes time, though it batches the results in memory, or something, while executing. The TRANSACTION method is also pretty expensive in both replication and query logs.
Even worse, the CASE method was 41.1x slower than the INSERT method w/ 30,000 records (6.1x slower than TRANSACTION). And 75x slower in MyISAM. INSERT and CASE methods broke even at ~1,000 records. Even at 100 records, the CASE method is BARELY faster.
So in general, I feel the INSERT method is both best and easiest to use. The queries are smaller and easier to read and only take up 1 query of action. This applies to both InnoDB and MyISAM.
Bonus stuff:
The solution for the INSERT non-default-field problem is to temporarily turn off the relevant SQL modes: SET SESSION sql_mode=REPLACE(REPLACE(##SESSION.sql_mode,"STRICT_TRANS_TABLES",""),"STRICT_ALL_TABLES",""). Make sure to save the sql_mode first if you plan on reverting it.
As for other comments I've seen that say the auto_increment goes up using the INSERT method, this does seem to be the case in InnoDB, but not MyISAM.
Code to run the tests is as follows. It also outputs .SQL files to remove php interpreter overhead
<?php
//Variables
$NumRows=30000;
//These 2 functions need to be filled in
function InitSQL()
{
}
function RunSQLQuery($Q)
{
}
//Run the 3 tests
InitSQL();
for($i=0;$i<3;$i++)
RunTest($i, $NumRows);
function RunTest($TestNum, $NumRows)
{
$TheQueries=Array();
$DoQuery=function($Query) use (&$TheQueries)
{
RunSQLQuery($Query);
$TheQueries[]=$Query;
};
$TableName='Test';
$DoQuery('DROP TABLE IF EXISTS '.$TableName);
$DoQuery('CREATE TABLE '.$TableName.' (i1 int NOT NULL AUTO_INCREMENT, i2 int NOT NULL, primary key (i1)) ENGINE=InnoDB');
$DoQuery('INSERT INTO '.$TableName.' (i2) VALUES ('.implode('), (', range(2, $NumRows+1)).')');
if($TestNum==0)
{
$TestName='Transaction';
$Start=microtime(true);
$DoQuery('START TRANSACTION');
for($i=1;$i<=$NumRows;$i++)
$DoQuery('UPDATE '.$TableName.' SET i2='.(($i+5)*1000).' WHERE i1='.$i);
$DoQuery('COMMIT');
}
if($TestNum==1)
{
$TestName='Insert';
$Query=Array();
for($i=1;$i<=$NumRows;$i++)
$Query[]=sprintf("(%d,%d)", $i, (($i+5)*1000));
$Start=microtime(true);
$DoQuery('INSERT INTO '.$TableName.' VALUES '.implode(', ', $Query).' ON DUPLICATE KEY UPDATE i2=VALUES(i2)');
}
if($TestNum==2)
{
$TestName='Case';
$Query=Array();
for($i=1;$i<=$NumRows;$i++)
$Query[]=sprintf('WHEN %d THEN %d', $i, (($i+5)*1000));
$Start=microtime(true);
$DoQuery("UPDATE $TableName SET i2=CASE i1\n".implode("\n", $Query)."\nEND\nWHERE i1 IN (".implode(',', range(1, $NumRows)).')');
}
print "$TestName: ".(microtime(true)-$Start)."<br>\n";
file_put_contents("./$TestName.sql", implode(";\n", $TheQueries).';');
}
UPDATE table1, table2 SET table1.col1='value', table2.col1='value' WHERE table1.col3='567' AND table2.col6='567'
This should work for ya.
There is a reference in the MySQL manual for multiple tables.
Use a temporary table
// Reorder items
function update_items_tempdb(&$items)
{
shuffle($items);
$table_name = uniqid('tmp_test_');
$sql = "CREATE TEMPORARY TABLE `$table_name` ("
." `id` int(10) unsigned NOT NULL AUTO_INCREMENT"
.", `position` int(10) unsigned NOT NULL"
.", PRIMARY KEY (`id`)"
.") ENGINE = MEMORY";
query($sql);
$i = 0;
$sql = '';
foreach ($items as &$item)
{
$item->position = $i++;
$sql .= ($sql ? ', ' : '')."({$item->id}, {$item->position})";
}
if ($sql)
{
query("INSERT INTO `$table_name` (id, position) VALUES $sql");
$sql = "UPDATE `test`, `$table_name` SET `test`.position = `$table_name`.position"
." WHERE `$table_name`.id = `test`.id";
query($sql);
}
query("DROP TABLE `$table_name`");
}
Why does no one mention multiple statements in one query?
In php, you use multi_query method of mysqli instance.
From the php manual
MySQL optionally allows having multiple statements in one statement string. Sending multiple statements at once reduces client-server round trips but requires special handling.
Here is the result comparing to other 3 methods in update 30,000 raw. Code can be found here which is based on answer from #Dakusan
Transaction: 5.5194580554962
Insert: 0.20669293403625
Case: 16.474853992462
Multi: 0.0412278175354
As you can see, multiple statements query is more efficient than the highest answer.
If you get error message like this:
PHP Warning: Error while sending SET_OPTION packet
You may need to increase the max_allowed_packet in mysql config file which in my machine is /etc/mysql/my.cnf and then restart mysqld.
There is a setting you can alter called 'multi statement' that disables MySQL's 'safety mechanism' implemented to prevent (more than one) injection command. Typical to MySQL's 'brilliant' implementation, it also prevents user from doing efficient queries.
Here (http://dev.mysql.com/doc/refman/5.1/en/mysql-set-server-option.html) is some info on the C implementation of the setting.
If you're using PHP, you can use mysqli to do multi statements (I think php has shipped with mysqli for a while now)
$con = new mysqli('localhost','user1','password','my_database');
$query = "Update MyTable SET col1='some value' WHERE id=1 LIMIT 1;";
$query .= "UPDATE MyTable SET col1='other value' WHERE id=2 LIMIT 1;";
//etc
$con->multi_query($query);
$con->close();
Hope that helps.
You can alias the same table to give you the id's you want to insert by (if you are doing a row-by-row update:
UPDATE table1 tab1, table1 tab2 -- alias references the same table
SET
col1 = 1
,col2 = 2
. . .
WHERE
tab1.id = tab2.id;
Additionally, It should seem obvious that you can also update from other tables as well. In this case, the update doubles as a "SELECT" statement, giving you the data from the table you are specifying. You are explicitly stating in your query the update values so, the second table is unaffected.
You may also be interested in using joins on updates, which is possible as well.
Update someTable Set someValue = 4 From someTable s Inner Join anotherTable a on s.id = a.id Where a.id = 4
-- Only updates someValue in someTable who has a foreign key on anotherTable with a value of 4.
Edit: If the values you are updating aren't coming from somewhere else in the database, you'll need to issue multiple update queries.
No-one has yet mentioned what for me would be a much easier way to do this - Use a SQL editor that allows you to execute multiple individual queries. This screenshot is from Sequel Ace, I'd assume that Sequel Pro and probably other editors have similar functionality. (This of course assumes you only need to run this as a one-off thing rather than as an integrated part of your app/site).
And now the easy way
update my_table m, -- let create a temp table with populated values
(select 1 as id, 20 as value union -- this part will be generated
select 2 as id, 30 as value union -- using a backend code
-- for loop
select N as id, X as value
) t
set m.value = t.value where t.id=m.id -- now update by join - quick
Yes ..it is possible using INSERT ON DUPLICATE KEY UPDATE sql statement..
syntax:
INSERT INTO table_name (a,b,c) VALUES (1,2,3),(4,5,6)
ON DUPLICATE KEY UPDATE a=VALUES(a),b=VALUES(b),c=VALUES(c)
use
REPLACE INTO`table` VALUES (`id`,`col1`,`col2`) VALUES
(1,6,1),(2,2,3),(3,9,5),(4,16,8);
Please note:
id has to be a primary unique key
if you use foreign keys to
reference the table, REPLACE deletes then inserts, so this might
cause an error
I took the answer from #newtover and extended it using the new json_table function in MySql 8. This allows you to create a stored procedure to handle the workload rather than building your own SQL text in code:
drop table if exists `test`;
create table `test` (
`Id` int,
`Number` int,
PRIMARY KEY (`Id`)
);
insert into test (Id, Number) values (1, 1), (2, 2);
DROP procedure IF EXISTS `Test`;
DELIMITER $$
CREATE PROCEDURE `Test`(
p_json json
)
BEGIN
update test s
join json_table(p_json, '$[*]' columns(`id` int path '$.id', `number` int path '$.number')) v
on s.Id=v.id set s.Number=v.number;
END$$
DELIMITER ;
call `Test`('[{"id": 1, "number": 10}, {"id": 2, "number": 20}]');
select * from test;
drop table if exists `test`;
It's a few ms slower than pure SQL but I'm happy to take the hit rather than generate the sql text in code. Not sure how performant it is with huge recordsets (the JSON object has a max size of 1Gb) but I use it all the time when updating 10k rows at a time.
The following will update all rows in one table
Update Table Set
Column1 = 'New Value'
The next one will update all rows where the value of Column2 is more than 5
Update Table Set
Column1 = 'New Value'
Where
Column2 > 5
There is all Unkwntech's example of updating more than one table
UPDATE table1, table2 SET
table1.col1 = 'value',
table2.col1 = 'value'
WHERE
table1.col3 = '567'
AND table2.col6='567'
UPDATE tableName SET col1='000' WHERE id='3' OR id='5'
This should achieve what you'r looking for. Just add more id's. I have tested it.
UPDATE `your_table` SET
`something` = IF(`id`="1","new_value1",`something`), `smth2` = IF(`id`="1", "nv1",`smth2`),
`something` = IF(`id`="2","new_value2",`something`), `smth2` = IF(`id`="2", "nv2",`smth2`),
`something` = IF(`id`="4","new_value3",`something`), `smth2` = IF(`id`="4", "nv3",`smth2`),
`something` = IF(`id`="6","new_value4",`something`), `smth2` = IF(`id`="6", "nv4",`smth2`),
`something` = IF(`id`="3","new_value5",`something`), `smth2` = IF(`id`="3", "nv5",`smth2`),
`something` = IF(`id`="5","new_value6",`something`), `smth2` = IF(`id`="5", "nv6",`smth2`)
// You just building it in php like
$q = 'UPDATE `your_table` SET ';
foreach($data as $dat){
$q .= '
`something` = IF(`id`="'.$dat->id.'","'.$dat->value.'",`something`),
`smth2` = IF(`id`="'.$dat->id.'", "'.$dat->value2.'",`smth2`),';
}
$q = substr($q,0,-1);
So you can update hole table with one query