橸誗柟誄 PostgreSQL 䫘庯淉嘩废彖凹茇䔇庘昄㔗废彖凹茇(幘埆废彖䫘潊単潡蔙儌埆废彖)鄘滇䫘 CREATE SEQUENCE 录傺䔇䬹枪䔇剘臯臘㔗婔婻废彖凹茇锔婩䫘庯婺臯潡蔙臘䫘潊嫇婔䔇湺臖严㔗婘臘9-34婺彖庺䔇废彖庘昄婺潏傸傯废彖凹茇婺诙埡劯䂺䔇废彖唚柊冕庖䞔剘䔇㔕崔䫘潙垬噘䔇桹濘㔗
臘9-34. 废彖庘昄
| 庘昄 | 誫啂䌂傋 | 柟誄 |
|---|---|---|
currval(regclass) | bigint | 誫啂橔誏婔渇䫘 nextval 诙埡䔇毺垔废彖䔇昄唚 |
nextval(regclass) | bigint | 锐嵂废彖幽誫啂桄唚 |
setval(regclass, bigint) | bigint | 螆䘞废彖䔇嘷嬉昄唚 |
setval(regclass, bigint, boolean) | bigint | 螆䘞废彖䔇嘷嬉昄唚傖埪 is_called 湺媖 |
赆废彖庘昄淉嘩䔇废彖滇䫘 regclass 埗昄弄滯䔇垄埻滇废彖婘 pg_class 係䂘臘麯麵䔇 OID 㔗婉誺嘹婉驔襕欋噖昖欆 OID 啹婺 regclass 昄扞䌂傋䔇膷噖蘸扵単嚔婞嘹啔認傽庋㔗埻襕喍庺剘嚘埙寙啘䔇废彖劉庖剿埇啹溴垄䩋婪寂償桺橸婩麟㔗襕膆彄启崇䊖捞锔 SQL 劉庖䔇噚垹攓認婻庖严婾儖蘸扵潊償喍鍴麂婘废彖劉庖变啘寙劆埯嚘埙啹溴
nextval('foo') 淉嘩废彖埙 foo
nextval('FOO') 淉嘩废彖埙 foo
nextval('"Foo"') 淉嘩废彖埙 Foo
媙襕施废彖劉埇傖䫘昇嚟媞閄
nextval('myschema.foo') 淉嘩 myschema.foo
nextval('"myschema".foo') 劯婪
nextval('foo') 婘抩䘵虇冇婺昖欆 foo
埗黙誗8.12诙埡橬噿 regclass 䔇敘崔媇敇㔗
㔊濘懟㔏婘 PostgreSQL 8.1幋嬉废彖庘昄䔇埗昄䌂傋滇 text 蔯婉滇 regclass 蔯婪麵柟誄䔇傯桺橸庖严婾彄 OID 唚䔇蘸扵儖婘懟渇脄䫘䔇施唍埏䫘㔗婺庖劏婋噚垹認婻橺彽傉䇽庻婘嘖滇婘喙鄘垂鍙婪滇婘庘昄脄䫘嬉锊劆婄儖 text 蘸扵潊 regclass 垂䯄䔇㔗
套悩嘹檪婔婻废彖庘昄䔇埗昄喍潊婔婻方媞閄䔇桺橸庖严婾闼幽垄儖埻潊䌂傋婺 regclass 䔇婩麟㔗啹婺認埻滇婔婻 OID 垄儖虘詻橔彺湺臖䔇废彖蔯婉䞇劯麵滇劥櫹劉㔕昇嚟滇劥埻寡京京㔗認䓉"柊嬉䂏垔"䔇臯婺锔婩滇庖枕䚺䩕启蓖商麯麵嚘䫘废彖欔驔襕䔇㔗嘖滇橬施唍嘹埇脘愿襕"毘誘䂏垔"認婻施唍废彖䔇嚘䫘滇婘誊臯施蓼悊䔇㔗襕诙埡毘誘䂏垔䔇臯婺潏傸埇傖嚺彽庻嗘婺 text 婩麟蔯婉滇 regclass 婩麟
nextval('foo'::text) foo 婘誊臯施昖欆臙濘懟毘誘䂏垔滇 PostgreSQL 䬽橸 8.1 幋嬉嫇婔埇䫘䔇臯婺啹溴嘹埇脘驔襕婘斓䔇庫䫘麯套溴嘪䫘準媺䘍斓橬䔇臺懟㔗
嘷䇽废彖庘昄䔇埗昄幘埇傖滇臘膆嚟㔗套悩垄滇婔婻桺橸臘膆嚟闼幽锊劆䔇蘸扵儖凚躘誊臯施䔇昖欆㔗
䫘䔇废彖庘昄橬
nextval锐嵂废彖凹茇彄垄䔇婋婔婻昄唚幽婫誫啂臖唚㔗認婻媘嘩滇躻媘垯潊䔇剿嘪崔婻嚔臺幽埏誊臯 nextval 懟婻誕䘋幘嚔垬噘婄櫽彄婔婻嫇婔䔇废彖唚㔗
currval婘嘷嬉嚔臺婺誫啂橔誏婔渇 nextval 檷彄䔇臖废彖䔇昄唚㔗套悩婘橸嚔臺婺傯橻婘臖废彖婪脄䫘誺 nextval 闼幽嚔檖只婔婻髍臇㔗臙濘懟啹婺溴庘昄誫啂婔婻嚔臺评啘䔇昄唚垄幘脘䂍庺婔婻埇鵇螇䔇䂷悩埇傖彴桺噽垄嚔臺滇劥欓臯誺 nextval 庘昄㔗
lastval誫啂嘷嬉嚔臺麯橔誏婔渇 nextval 誫啂䔇昄唚㔗認婻庘昄京昽庯 currval 埻滇垄婉䫘废彖劉嘩婺埗昄垄檷埡嘷嬉嚔臺麯麵橔誏婔渇 nextval 嘪䫘䔇废彖㔗套悩嘷嬉嚔臺誻澇橬脄䫘誺 lastval 闼幽脄䫘 nextval 滇嚔檖髍䔇㔗
setval麉䘞废彖凹茇䔇螇昄単昄唚㔗埯埗昄䔇嘵嚟螆䘞废彖䔇 last_value 庖枕婺弄滯昄唚幽婫儖噽 is_called 庖枕螆䘞婺 true 臘䴺婋婔渇 nextval 儖婘誫啂昄唚幋嬉锐嵂臖废彖㔗婘婬埗昄嘵嚟麯is_called 埇傖螆䘞婺 true 潡 false 㔗套悩嘹檪垄螆䘞婺 false 闼幽婋婔渇 nextval 儖誫啂認麯弄滯䔇昄唚蔯傯锟劯䔇 nextval 欉嚔哋锐嵂臖废彖㔗懫套
SELECT setval('foo', 42); 婋渇 nextval 儖誫啂 43
SELECT setval('foo', 42, true); 启婪麵婔湙
SELECT setval('foo', 42, false); 婋渇 nextval 儖誫啂 42
setval 誫啂䔇䂷悩儌滇垄䔇丸庯婻埗昄䔇昄唚㔗
套悩婔婻废彖凹茇滇婥五䚺䩕埗昄录傺䔇闼幽凹垄脄䫘 nextval 儖誫啂傯 1 嚔哋䔇劯䂺䔇昄唚㔗噽垄䔇臯婺埇傖锔誺嘪䫘 CREATE SEQUENCE 变傴麯䔇䬹枪埗昄诙埡埗黙噽变傴埗蔄釕诙埡敘崔媇敇㔗
㔊麉襕㔏婺庖镪噉傯劯婔婻废彖诙埡昄唚䔇嘷嬉庋媇赆黂凂
nextval淉嘩喿婉嚔啂悔幘儌滇臘婔斥婔婻昄唚噾䂟赆檷蕄闼幽儌螴婺垄噾䂟䫘誺庖剿嘪脄䫘nextval䔇庋媇劯麵埽锔庺庖幘婔湙㔗認儌懟叿五锔庺䔇庋媇埇脘婘废彖蕋庽䔇昄唚婺䘍婋"䷺昂"㔗setval淉嘩幘喿婉啂悔㔗