Multiple Updates in MySQL

问题:

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; 

回答1:

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); 

回答2:

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); 

回答3:

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.

回答4:

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; 

回答5:

All of the following applies to InnoDB.

I feel knowing the speeds of the 3 different methods is important.

There are 3 methods:

1. INSERT: INSERT with ON DUPLICATE KEY UPDATE
2. TRANSACTION: Where you do an update for each record within a transaction
3. 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: . 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, I tested that too and it seems to not be the case.

Code to run the tests is as follows. It also outputs .SQL files to remove php interpreter overhead

 //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\n";      file_put_contents("./$TestName.sql", implode(";\n", $TheQueries).';'); } 

回答6:

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.

回答7:

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`"); } 

回答8:

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.

回答9:

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.

回答10:

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.

回答11:

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.

回答12:

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

回答13:

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' 

回答14:

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)

回答15:

With PHP I did this. Use semicolon, split it into array and then submit via loop.

$con = new mysqli('localhost','user1','password','my_database'); $batchUpdate = true; /*You can choose between batch and single query */ $queryIn_arr = explode(";", $queryIn);  if($batchUpdate)    /* My SQL prevents multiple insert*/ {     foreach($queryIn_arr as $qr)     {         if(strlen($qr)>3)         {             //echo '
Sending data to SQL1:
'.$qr.'';             $result = $conn->query($qr);         }      } } else {     $result = $conn->query($queryIn); } $con->close(); 

回答16:

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.

回答17:

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

文章来源: Multiple Updates in MySQL