sql execution plan - SQL chain AND operator, all executed? -

-

i wondering if in sql request using several , statement, every , executed or triggered when previous , ok?

in example :

select * my_table when > 5 , b < 10

if condition > 5 not respected, test b < 10 triggered? or in java triggered when > 5 valid?

thanks ;)

bye !

in general, sql engines implement "short-circuiting", meaning execution of conditions stops when final value known.

however, pretty unimportant. first, cannot depend on order of evaluation of conditions. so, don't know evaluated first. second, engine may use alternative execution paths (such using indexes).

and, finally, short-circuiting typically has minimal impact on performance. reading data typically more important. 1 exception when 1 of conditions uses complex functions. in case, use case or subqueries ensure order of execution.


Comments

Post a Comment

Popular posts from this blog

ios - RestKit 0.20 — CoreData: error: Failed to call designated initializer on NSManagedObject class (again) -

-
this error has shown on many times, seems. prominent answer issue seems restkit 0.20 — coredata: error: failed call designated initializer on nsmanagedobject class however, solution posted doesn't work me. let's start beginning: i want upload file server. want parse response make sure uploaded. if not, try again later. model has boolean variable called nsnumber *senttoserver purpose (in coredata, bool saved nsnumber ) . because don't know whether sending going successful, save entity coredata model first before sending via restkit. when post request successful, server returns json string this: {"id":14,"created":true} notice that, of course, id not set on coredata model yet, both id , created new informations model. here's model: @interface recording : nsmanagedobject @property (nonatomic, retain) nsstring * audiofilepath; @property (nonatomic, retain) nsdate * createdat; @property (nonatomic, retain) nsstring * deviceid; @
Read more

laravel - PDOException in Connector.php line 55: SQLSTATE[HY000] [1045] Access denied for user 'root'@'localhost' (using password: YES) -

-
my .env: app_env=local app_debug=true app_key=myappkey app_url=http://localhost db_connection=mysql db_host=localhost db_port=3306 db_database=gestiontaller db_username=root db_password='root' cache_driver=file session_driver=file queue_driver=sync redis_host=127.0.0.1 redis_password=null redis_port=6379 mail_driver=smtp mail_host=mailtrap.io mail_port=2525 mail_username=null mail_password=null mail_encryption=null i've tried password ", ' , without, restarting server every time. i've tried changing localhost 172.0.0.1. yes, password correct, running mysql -u root -p introducing password root in prompt can go mysql. users table: +------------------+-----------+ | user | host | +------------------+-----------+ | debian-sys-maint | localhost | | mysql.sys | localhost | | root | localhost | | root1 | localhost | +------------------+-----------+ i've added homestead.yaml this: database_port: 3306
Read more

java - Digest auth with Spring Security using javaconfig -

-
so i'm trying create digest authentication spring following documentation trying translate xml "requirements" in java requirements. let's have xml in docs: <bean id="digestfilter" class= "org.springframework.security.web.authentication.www.digestauthenticationfilter"> <property name="userdetailsservice" ref="jdbcdaoimpl"/> <property name="authenticationentrypoint" ref="digestentrypoint"/> <property name="usercache" ref="usercache"/> </bean> <bean id="digestentrypoint" class= "org.springframework.security.web.authentication.www.digestauthenticationentrypoint"> <property name="realmname" value="contacts realm via digest authentication"/> <property name="key" value="acegi"/> <property name="noncevalidityseconds" value="10"/> </b
Read more