sql - DMBS: Union, intersection and difference with PhpMyAdmin and MySql opninons -

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i'm learning sql , friend adviced me instal xampp it's preconfigured , ready use. well, installed , created 2 databases on exercise through phpmyadmin. said, i'm trying 2 things:

a)sets operationsunion, intersect, difference. available in phpmyadmin (and therefore mysql guess, since noticed phpmyadmin based on mysql) union. intersect , difference keywords not exist. how then?

b)using directly mysql.exe console. try use commands use databasename , on, says "access denied user ''@'localhost 'databasename'

i tried put connect commands in flavours possible (connect user pass host db, connect user pass db, , kind of combinations) no avail.

how that? seems phpmyadmin set own passwords databases. put empty password , checked in phpmyadmin password empty passwords. doing wrong?

union keyword work fine on phpmyadmin. phpmyadmin interface mysql. try use "sql" view in phpmyadmin directly test sql queries.

if comes mysql.exe, try connect using user e.g. root@localhost. default there should no password root.


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