11.6. 臘膆嚟婪䔇䘵嚘

䘵嚘幽麂婔垔襕滇婔婻庘北臘䔇庖枕誻埇傖滇婔婻庘昄潡蔙傯婔婻潡崔婻庖枕螇䞖庺準䔇湺麟臘膆嚟㔗認婻䬹攓凹庯媆锘螪閞闼底嘺庯螇䞖䂷悩䔇臘麂婩橬䫘㔗

懫套啔崓償喍方噿懫膄䔇婩䫘桹濘滇嘪䫘 lower 庘昄

SELECT * FROM test1 WHERE lower(col1) = 'value';

套悩潏傸婘 lower(col1) 淉嘩䔇䂷悩婪垔幬䘵嚘

CREATE INDEX test1_lower_col1_idx ON test1 (lower(col1));

闼幽婪誄昖臵儌埇傖嘪䫘臖䘵嚘㔗套悩潏傸檪認婻䘵嚘弄滯婺 UNIQUE 闼幽垄嚔䥕溵录傺闼䓉 col1 昄唚埻滇崓償喍橬彆潡垯噘䕩劯䔇昄扞臯㔗啹溴婘臘膆嚟婪䔇䘵嚘埇傖䫘庯嚺彽闼底方濘垔幬婺䞔剘嫇婔亥溘䔇亥溘㔗

埥崡婔婻冋床滇套悩潏傸䂟婩嘪䫘婋麵認湙䔇昖臵

SELECT * FROM people WHERE (first_name || ' ' || last_name) = 'John Smith';

闼幽潏傸儌唚冖录傺婋麵認湙䔇䘵嚘

CREATE INDEX people_names ON people ((first_name || ' ' || last_name));

CREATE INDEX 变傴䔇臺濘锔婩襕挗婘䘵嚘臘膆嚟变啘幥喍婖拸嚓儌償潏傸婘丸庯婻冋床麯滆䴺䔇闼湙㔗套悩臘膆嚟埻滇婔婻庘昄脄䫘闼幽埇傖䩕䘖儌償潏傸婘丸婔婻冋床麯滆䴺䔇闼湙㔗

傯䂘檴蓐庥準䩋䘵嚘臘膆嚟䕩凹蘹媾婔底啹婺婘某噖昄扞臯潡蔙敘桄昄扞臯䔇施唍鄘媙釂婺懟婔臯螇䞖䫘潊䔇臘膆嚟㔗婉誺䘵嚘臘膆嚟婉滇婘䘵嚘昖欆䔇施唍誕臯螇䞖䔇啹婺垄傸噾䂟庻嗘婘䘵嚘麯庖㔗婘婪麵䔇婴婻冋床麯係䂘鄘檪昖臵䩋啔埻滇 WHERE indexedcolumn = 'constant' 欔傖抩䘵䔇锘庥京昽庯傂嘘噽垄䞔剘䔇䘵嚘昖臵㔗啹溴臘膆嚟婪䔇䘵嚘婘演䘵锘庥懫某噖启敘桄锘庥敘麉襕䔇婺劽婋滇橬䫘䔇㔗