sql one : select * from table_name where id = **; sql two : select count() from table_name where id = **;
I test the two sql statement. It almost the same speed. At 2016-03-10 16:29:16, "Hick Gunter" <hick at scigames.at> wrote: >Assuming the "id" is the primary key of your table "table_name", your >statement will list the id of all the records present (full scan, reading >every entry of the implicit primary key index). > >To find out if a specific record exists, use "select count() from table_name >where id = <key value>" to return a single row with the number of records >found. This may be faster only if id has a primary key or unique constraint or >is the first field of a declared index. > >-----Urspr?ngliche Nachricht----- >Von: sqlite-users-bounces at mailinglists.sqlite.org >[mailto:sqlite-users-bounces at mailinglists.sqlite.org] Im Auftrag von Jim >Wang >Gesendet: Donnerstag, 10. M?rz 2016 09:01 >An: sqlite-users at mailinglists.sqlite.org >Betreff: [sqlite] jude a record is exist or not > >hi,all > As usual, we judge a record is exist or not in a data base is :select id > from table_name. > Except the above method, Is there any method which could judge a record is > exist or not much faster than the above method. > > I am looking forward to hearing from you. > Jim Wang. >_______________________________________________ >sqlite-users mailing list >sqlite-users at mailinglists.sqlite.org >http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users > > >___________________________________________ > Gunter Hick >Software Engineer >Scientific Games International GmbH >FN 157284 a, HG Wien >Klitschgasse 2-4, A-1130 Vienna, Austria >Tel: +43 1 80100 0 >E-Mail: hick at scigames.at > >This communication (including any attachments) is intended for the use of the >intended recipient(s) only and may contain information that is confidential, >privileged or legally protected. Any unauthorized use or dissemination of this >communication is strictly prohibited. If you have received this communication >in error, please immediately notify the sender by return e-mail message and >delete all copies of the original communication. Thank you for your >cooperation. > > >_______________________________________________ >sqlite-users mailing list >sqlite-users at mailinglists.sqlite.org >http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users
