Mysql Update Another Table With Trigger Warning' title='Mysql Update Another Table With Trigger Warning' />Databases Django documentation Django. Django attempts to support as many features as possible on all database. However, not all database backends are alike, and weve had to make. This file describes some of the features that might be relevant to Django. FBR/0G18/IZ6CR7M7/FBR0G18IZ6CR7M7.MEDIUM.jpg' alt='Mysql Update Another Table With Trigger Warning' title='Mysql Update Another Table With Trigger Warning' />We know youve got a cool bag with some smart ideas inside, so let us know Share your bag in our Lifehacker Go Bag Show and Tell Flickr pool, shoot me a message. Of course, it is not intended as a replacement for server specific. General notesPersistent connectionsPersistent connections avoid the overhead of re establishing a connection to. Theyre controlled by the. CONNMAXAGE parameter which defines the maximum lifetime of a. It can be set independently for each database. The default value is 0, preserving the historical behavior of closing the. To enable persistent. After doing substantial insert, update, or delete operations on an InnoDB table that has its own. UPDATE is a DML statement that modifies rows in a table. Singletable syntax UPDATE LOWPRIORITY IGNORE tablereference SET assignmentlist WHERE where. CONNMAXAGE to a positive number of seconds. For. unlimited persistent connections, set it to None. Connection managementDjango opens a connection to the database when it first makes a database. It keeps this connection open and reuses it in subsequent requests. Django closes the connection once it exceeds the maximum age defined by. CONNMAXAGE or when it isnt usable any longer. In detail, Django automatically opens a connection to the database whenever it. At the beginning of each request, Django closes the connection if it has. If your database terminates idle connections after. CONNMAXAGE to a lower value, so that. Django doesnt attempt to use a connection that has been terminated by the. This problem may only affect very low traffic sites. At the end of each request, Django closes the connection if it has reached its. If any database. errors have occurred while processing the requests, Django checks whether the. Thus, database errors. CaveatsSince each thread maintains its own connection, your database must support at. Sometimes a database wont be accessed by the majority of your views, for. In such cases, you should set CONNMAXAGE to a low value or even. This will help keep the number of simultaneous connections to. The development server creates a new thread for each request it handles. Dont enable them during. When Django establishes a connection to the database, it sets up appropriate. If you enable persistent. If you modify. parameters such as the connections isolation level or time zone, you should. Djangos defaults at the end of each request, force an. EncodingDjango assumes that all databases use UTF 8 encoding. Using other encodings may. Django. See the database specific notes. Postgre. SQL notesDjango supports Postgre. SQL 9. 3 and higher. Postgre. SQL connection settingsSee HOST for details. Optimizing Postgre. SQLs configurationDjango needs the following parameters for its database connections clientencoding UTF8,defaulttransactionisolation readcommitted by default. UTC when USETZ is True, value of. TIMEZONE otherwise. If these parameters already have the correct values, Django wont set them for. You can configure. ALTER ROLE. Django will work just fine without this optimization, but each new connection. Isolation levelLike Postgre. SQL itself, Django defaults to the READCOMMITTEDisolation. If you need a higher isolation level such as REPEATABLEREAD or. SERIALIZABLE, set it in the OPTIONS part of your database. DATABASES importpsycopg. DATABASES. OPTIONS isolationlevel psycopg. ISOLATIONLEVELSERIALIZABLE,Note. Under higher isolation levels, your application should be prepared to. This option is. designed for advanced uses. Indexes for varchar and text columnsWhen specifying dbindexTrue on your model fields, Django typically. CREATEINDEX statement. However, if the database type. Char. Field. File. Field, and Text. Field, then Django will create. Postgre. SQL operator class. The extra index is necessary to correctly perform. LIKE operator in their SQL, as is done with the. Migration operation for adding extensionsIf you need to add a Postgre. SQL extension like hstore, postgis, etc. Create. Extension operation. Free Adobe Photoshop Plugin Filters here. Manually specifying values of auto incrementing primary keysDjango uses Postgre. SQLs SERIAL data type to store auto incrementing primary. A SERIAL column is populated with values from a sequence that. Manually assigning a value to an. For example fromdjango. User User. User alice The sequence hasnt been updated its next value is 1. User. Integrity. Error duplicate key value violates unique constraintauthuserpkey DETAIL Key id1 already exists. If you need to specify such values, reset the sequence afterwards to avoid. The sqlsequencereset. SQL statements to do that. Test database templatesYou can use the TESTTEMPLATE setting to specify. Speeding up test execution with non durable settingsYou can speed up test execution times by configuring Postgre. SQL to be. non durable. Warning. This is dangerous it will make your database more susceptible to data loss. Only use this on. My. SQL notesVersion supportDjango supports My. SQL 5. 5 and higher. Djangos inspectdb feature uses the informationschema database, which. Django expects the database to support Unicode UTF 8 encoding and delegates to. It is important. to be aware of the fact that the two latter ones arent actually enforced by. My. SQL when using the My. ISAM storage engine, see the next section. Storage enginesMy. SQL has several storage engines. You can change the default storage engine. Until My. SQL 5. 5. My. ISAM1. The main drawbacks of. My. ISAM are that it doesnt support transactions or enforce foreign key. On the plus side, it was the only engine that supported full text. My. SQL 5. 6. 4. Since My. SQL 5. 5. 5, the default storage engine is Inno. DB. This engine is fully. Its probably the best. However, note that the Inno. DB autoincrement counter. My. SQL restart because it does not remember the. AUTOINCREMENT value, instead recreating it as maxid1. This may. result in an inadvertent reuse of Auto. Field values. If you upgrade an existing project to My. SQL 5. 5. 5 and subsequently add some. My. ISAM. vs. Inno. DB. Specifically, if tables that have a Foreign. Key between them. Operational. Error 1. Cant create table dbname. My. SQL DB API DriversThe Python Database API is described in PEP 2. My. SQL has three prominent. API My. SQLdb is a native driver that has been developed and supported for over. Andy Dustman. mysqlclient is a fork of My. SQLdb which notably supports Python 3 and. My. SQLdb. At the time of this writing. My. SQL with Django. My. SQL ConnectorPython is a pure Python driver from Oracle that does not. My. SQL client library or any Python modules outside the standard. All these drivers are thread safe and provide connection pooling. My. SQLdb. is the only one not supporting Python 3 currently. In addition to a DB API driver, Django needs an adapter to access the database. ORM. Django provides an adapter for My. SQLdbmysqlclient while. My. SQL ConnectorPython includes its own. My. SQLdbDjango requires My. SQLdb version 1. 2. At the time of writing, the latest release of My. SQLdb 1. 2. 5 doesnt support. Python 3. In order to use My. SQLdb under Python 3, youll have to install. Note. There are known issues with the way My. SQLdb converts date strings into. Specifically, date strings with value 0. My. SQL but will be converted into None by My. SQLdb. This means you should be careful while using loaddata and. None. mysqlclientDjango requires mysqlclient 1. My. SQLdb. My. SQL ConnectorPythonMy. SQL ConnectorPython is available from the download page. The Django adapter is available in versions 1. X and later. It may not. PHP mysqlinsertid Manual. If you insert a data row by using the ON DUPLICATE KEY UPDATE clause in an INSERT statement, the mysqlinsertid function will return not the same results as if you directly use LASTINSERTID in My. SQL. See the following example lt insert a datarow, primary key is autoincrement value is a unique keyquery INSERT INTO test value VALUES test mysqlquery query    echo LASTINSERTID ,mysqlquery SELECT LASTINSERTID ,lt br mysqlinsertid ,mysqlinsertid This will print LASTINSERTID 1mysqlinsertid 1. In this case the function returns the same as the My. SQL Statement. But see the insert on an existing key lt query INSERT INTO test value VALUES testON DUPLICATE KEY UPDATE value test. LASTINSERTID ,mysqlquery SELECT LASTINSERTID ,lt br mysqlinsertid ,mysqlinsertid This will print LASTINSERTID 2mysqlinsertid 1. By using the ON DUPLICATE KEY UPDATE clause, only the old datarow will be modified, if the INSERT statement causes a duplicate entry, but the LASTINSERTID function returns the next autoincrement value for the primary key, which is by the way not set as the next autoincrement value in the database. The mysqlinsertid function returns the primary key of the old and changed data row. For me this is the right operation method, because the LASTINSERTID function returns a value which is not referenced to a data row at all. Greets from Munich.