sql - why do i need left outer join if i have right outer join? -

-

possible duplicate:
when or why use right outer join instead of left?

what ever functionality left outer join can interchanging table names.then, need having 2 outer joins ( left , right) ? if there specific need can body explain example ?

why use >= when < same thing?

mostly it's convenience thing.


Comments

Post a Comment

Popular posts from this blog

silverlight - Applying a style to ItemContainerStyle in C# -

-
when i'm applying style listbox.itemcontainerstyle in c# isn't making change @ runtime. i'm using; mylistbox.itemcontainerstyle = (style)(app.current.resources["newitemstyle"]); however other styles being supplied, such buttons etc i'm going mybutton.style = (style)(app.current.resources["mymainbuttonstyle"]); i don't errors either, nothing , reverts default system style. i using app.current.resources instead of resources because "newitemstyle" wasn't defined in whole application. mistake.
Read more

php - Retrieving comment count from fb:comments widget (Facebook) -

-
i've tried using both javascript , php sdks, can't solve simple problem. my fql looks like: select count comments_info xid="..." when attempt request through php, following error: uncaught exception: 604: no valid app_id php: $facebook = new facebook(array( 'appid' => '...', 'secret' => '...', 'cookie' => true )); $result = $facebook->api(array( 'method' => 'fql.query', 'query' => 'select count comments_info xid="'.[...].'"' )); the appid , secret copied application page in facebook developer app. similarly, when use js api, in: var query = fb.data.query('select count comments_info xid="' + [...] + '"'); query.wait(function(rows){}); ... same error in jsonp response: fb.apiserver._callbacks.f2ba554518({"error_code":"604","error_msg":"no valid app_id"...
Read more

c# - NullReferenceException in MySqlClient.NativeDriver -

-
i have long running program exectues mysql-queries every 5 minutes (timed thread). after has run approximately 10 hours nullreferenceexception thrown following stacktrace: at mysql.data.mysqlclient.nativedriver.getresult(int32& affectedrow, int32& insertedid) bei mysql.data.mysqlclient.driver.getresult(int32 statementid, int32& affectedrows, int32& insertedid) @ mysql.data.mysqlclient.driver.nextresult(int32 statementid) @ mysql.data.mysqlclient.mysqldatareader.nextresult() @ mysql.data.mysqlclient.mysqldatareader.close() @ mysql.data.mysqlclient.mysqlcommand.resetreader() @ mysql.data.mysqlclient.mysqlcommand.executereader(commandbehavior behavior) @ mysql.data.mysqlclient.mysqlcommand.executenonquery() @ myownprogram.mysql.senddata(string sqlcommmand) the senddata method following (lockdb of type object) public void senddata(string sqlcommmand) { try { using(mysqlcommand command = connection.createcommand()...
Read more