https://www.jianshu.com/p/d465a4c748e8
atlasdb=# select id from generate_series(1,10) t(id);
(10 rows)
generate_series 可以指定最大值，最小值，递增值。也可以生成时间等类型
atlasdb=# \df generate_series
List of functions
Schema | Name | Result data type | Argument data types | Type
------------+-----------------+-----------------------------------+--------------------------------------------------------------------+------
pg_catalog | generate_series | SETOF bigint | bigint, bigint | func
pg_catalog | generate_series | SETOF bigint | bigint, bigint, bigint | func
pg_catalog | generate_series | SETOF integer | integer, integer | func
pg_catalog | generate_series | SETOF integer | integer, integer, integer | func
pg_catalog | generate_series | SETOF numeric | numeric, numeric | func
pg_catalog | generate_series | SETOF numeric | numeric, numeric, numeric | func
pg_catalog | generate_series | SETOF timestamp without time zone | timestamp without time zone, timestamp without time zone, interval | func
pg_catalog | generate_series | SETOF timestamp with time zone | timestamp with time zone, timestamp with time zone, interval | func
(8 rows)
atlasdb=# select random() from generate_series(1,10);
random
--------------------
0.799458883237094
0.047981650128836
0.211289744824171
0.909943440463394
0.795472401659936
0.780012475326657
0.568553290329874
0.434846977703273
0.192123426124454
0.605796394404024
(10 rows)
random()生成值为双精度浮点数，范围 0 <= random() < 1
生成指定范围的整数：min+(random()*(max-min))::integer
atlasdb=# select 5+(random()*(7-5))::integer from generate_series(1,10);
?column?
----------
(10 rows)
随机字符串
# 生成指定长度的字符串
create or replace function f_random_str(length INTEGER)
returns character varying AS $$
DECLARE
result varchar(50);
BEGIN
SELECT array_to_string(ARRAY(SELECT chr((65 + round(random() * 25)) :: integer)
FROM generate_series(1,length)), '') INTO result;
return result;
$$ LANGUAGE plpgsql;
方案2：利用md5函数
md5(random()::text)
atlasdb=# select md5(random()::text),f_random_str(5) from generate_series(1,10);
md5 | f_random_str
----------------------------------+--------------
a56bcf9d7f81780019042a67064a9c0e | NDOGV
dec8db00b3059650f7ab7f22d004069e | WQLBH
d20997f727a1d567ee0705d54b305474 | KOWVJ
0056c14bcd1455d6f53515cddcbfe1fa | NXRBH
04fb3acae29234381b9b96611af8ad94 | QVBBN
b933eb17c3deb2a4391873ca95cc9288 | QBJFH
2d8361fd230cd34d0038c4340553d27d | BDVME
925004f93aa3541b43e8168aff77fc62 | TOQQK
a7f4a7e36792310f561bf861d09cc80d | MXYEZ
d3d4f6b1777d3015be4fd9f38876da4f | EQCFR
(10 rows)
重复字符串
repeat('abc', 10)
atlasdb=# select repeat(f_random_str(5),3) from generate_series(1,10);
repeat
-----------------
XDODDXDODDXDODD
UHTWLUHTWLUHTWL
LMWTDLMWTDLMWTD
RHAQVRHAQVRHAQV
BLWGJBLWGJBLWGJ
RBXDFRBXDFRBXDF
NBJCENBJCENBJCE
LVKFSLVKFSLVKFS
WQFTKWQFTKWQFTK
ILRICILRICILRIC
(10 rows)
create or replace function gen_hanzi(int) returns text as $$
declare
res text;
begin
if $1 >=1 then
select string_agg(chr(19968+(random()*20901)::int), '') into res from generate_series(1,$1);
return res;
end if;
return null;
$$ language plpgsql strict;
atlasdb=# select gen_hanzi(10) from generate_series(1,10);
gen_hanzi
----------------------
狶用裻羾愪諮夛鞳店蓝
譣鞇县跆硠銚巖眐韎盍
訂锕短峂销淼椚煟閴篁
尰椅元霫髃摮艳吹屼錊
謖駟諬郖蠀控菋韖買篴
滾眔煤飫藖暿杂佌訞嵑
紌顎硖聏返獴隽犢禭厔
昈攟齳兏噐蟍曶谚翾合
桪佗紜诎驂捎勨懟撙輇
焯鎥螰鮅瑐矟潕歨鲁鬂
(10 rows)
atlasdb=# create table testdata(id integer,name varchar(20),course int,grade numeric(4,2),testtime date,note text);
CREATE TABLE
atlasdb=# insert into testdata
atlasdb-# select generate_series(1,100) as id,
atlasdb-# f_random_str(3+(random()*5)::integer) as name,
atlasdb-# (random()*100)::integer as course,
atlasdb-# (random()*99)::numeric(4,2) as grade,
atlasdb-# now() - ((random()*1000)::integer||' day')::interval as testtime,
atlasdb-# gen_hanzi(3+(random()*5)::integer) as note;
INSERT 0 100
atlasdb=# select * from testdata;
id | name | course | grade | testtime | note
-----+----------+--------+-------+------------+------------------
1 | GGLHI | 13 | 59.61 | 2019-03-07 | 蔱澪豇抨寓蛤矶
2 | YUBJ | 64 | 72.51 | 2018-07-18 | 戇覃璢廣
3 | XMWITG | 46 | 35.76 | 2018-07-24 | 儋襫鵆斳
4 | RUDPPEY | 24 | 87.59 | 2018-08-08 | 增偗酚榁蜷
5 | UPBOVNX | 14 | 71.70 | 2016-10-20 | 蛃戵貋殤刹雟鵇
6 | BYWXGG | 6 | 27.58 | 2019-04-03 | 鷵蹦帅紽鋖
7 | KJROCQK | 78 | 87.08 | 2018-12-05 | 騊叻圵紲
8 | CMBI | 70 | 10.63 | 2017-10-21 | 眦粚笈蜪娲渹猨
9 | TDCVTN | 62 | 63.53 | 2017-07-09 | 糋貵锗婗陙騺耮
10 | GIBVCOKQ | 25 | 55.26 | 2019-05-11 | 圣越量彁聄繣褺
11 | GLZU | 19 | 85.19 | 2016-10-18 | 軖糏京
12 | WBW | 97 | 58.88 | 2018-08-21 | 銙錈肮稦鰫溓
13 | EAYWG | 20 | 31.12 | 2018-10-11 | 眉嗦鲽
14 | WNPXLQ | 81 | 38.91 | 2018-10-18 | 黈厰髿
15 | PXAZCB | 95 | 95.38 | 2018-09-07 | 撮睛娴趶
16 | DJMQYL | 8 | 57.14 | 2018-10-11 | 进椷玖開撐
17 | MEC | 47 | 24.36 | 2019-02-21 | 弛沃箂痉闞
18 | HMVQYMO | 40 | 54.48 | 2019-01-10 | 侼鮪鵤畓醐扏
19 | ILQURS | 20 | 87.24 | 2019-02-15 | 氖黃玕臰璘擳捑
20 | TVVIY | 49 | 32.18 | 2016-11-22 | 远譣衉歋卤
21 | ZVUS | 4 | 68.55 | 2017-02-19 | 勺酃挖蛫昵稉鰼
22 | HUPPTCX | 68 | 55.27 | 2017-06-06 | 携唛眀澞呕
23 | GUKXQ | 19 | 96.67 | 2018-02-27 | 蓾诪黢膕眿
24 | KDWE | 20 | 79.37 | 2017-01-22 | 祄晦偧聞轥爅蚴
25 | RMOO | 14 | 73.23 | 2017-11-25 | 嶘悾欐峕鑓鑏
26 | HYJLE | 15 | 31.78 | 2016-11-23 | 肚鮿旼灛渟麰
27 | BMDQQV | 19 | 21.73 | 2019-04-15 | 系惣攲熥蛝
28 | KBBOFJ | 49 | 85.68 | 2016-10-14 | 嬀浖鉢娋鰑
29 | QCNGXSM | 98 | 14.68 | 2019-04-15 | 煍痂顧齘
30 | YALEJYA | 32 | 39.14 | 2018-12-20 | 愄枡葈塵魜詫菫
31 | RKRQ | 53 | 72.10 | 2017-01-13 | 従跷鲝嚟訡鸢簠閳
32 | NWRXB | 38 | 14.30 | 2018-06-03 | 摀枒跑
33 | NLIFDVXZ | 82 | 13.62 | 2017-04-27 | 懛眸豞迻浅囁桻
34 | TGIE | 38 | 67.90 | 2018-11-22 | 龑鶣緑砐焭韙
35 | OTQNOTH | 36 | 1.23 | 2017-03-24 | 郿崖惔姕
36 | AKTET | 46 | 34.83 | 2018-04-16 | 梸龚鵸该韎
37 | IRIVGC | 13 | 59.21 | 2019-02-28 | 裧飔均鮻匄籆鰷爚
38 | DFUMP | 26 | 78.73 | 2017-09-26 | 笭硾颐鏐
39 | GRLI | 81 | 1.83 | 2018-04-23 | 詪桩鏏蚀浭灰茓
40 | TTBOGQU | 3 | 26.11 | 2019-04-16 | 踇鲍熾鳡嵼堌
41 | NXKXR | 15 | 22.88 | 2017-12-19 | 聊鯞症爬衬抯璥
42 | MDCN | 38 | 14.21 | 2019-02-24 | 嚡秞壿昜
43 | NUPXSH | 7 | 92.53 | 2017-03-21 | 竵误湒鼡璶茂琡證
44 | PVQY | 99 | 74.56 | 2019-01-15 | 斷摸淔
45 | UFOSWUUV | 62 | 69.62 | 2018-05-25 | 嘗氓鏻謘鈴
46 | WLLNKL | 29 | 53.00 | 2017-12-14 | 逮馣禅羐圩咄
47 | AWDVN | 83 | 19.84 | 2016-12-09 | 籯豣蔟滾汜箼醆酛
48 | GHK | 76 | 79.55 | 2016-10-04 | 覗睋屉鋁総眺
49 | MQRALWX | 38 | 43.41 | 2017-07-24 | 鋌刽肐
50 | WSWEDQ | 95 | 8.04 | 2018-10-30 | 緭添硦尗霶殤
51 | NBRZXP | 37 | 33.73 | 2018-09-14 | 峸枭净鎥嶟
52 | TIWKHYP | 96 | 53.54 | 2019-06-02 | 蠾靟銿汉炰
53 | BKTQTDW | 20 | 29.77 | 2018-11-19 | 媌涷伀靗
54 | WHAVXYJ | 90 | 44.03 | 2019-03-03 | 敩珚悕嬨盫自骑
55 | KBAP | 36 | 19.90 | 2017-01-23 | 縟镥潌枎诼蜞
56 | PPHYN | 73 | 6.90 | 2018-07-31 | 禋秂屽
57 | EDE | 58 | 16.87 | 2018-12-26 | 磷歰募僫
58 | XLHREPHT | 87 | 26.55 | 2018-09-27 | 榖管耆锡喾躂
59 | HXCVCGBP | 58 | 10.61 | 2017-09-04 | 兞咣軝觺恔沽
60 | YGH | 22 | 83.14 | 2017-09-10 | 狱眐镐懎潝奰娔
61 | ZGRBV | 27 | 14.33 | 2018-02-26 | 崰穹绠餪賍鶝魃
62 | FGYBWSN | 37 | 60.42 | 2017-05-12 | 譅鞔抲詷堲鬞越
63 | FXKBDYPB | 73 | 58.91 | 2016-10-01 | 遬徤炪锭唯
64 | KMTD | 25 | 51.71 | 2019-04-28 | 捶嬶牄兛圬
65 | YNRCMI | 10 | 21.07 | 2016-12-18 | 蕲蠑昐
66 | PKHY | 85 | 3.67 | 2019-02-23 | 箪奇繇
67 | HBWKRVX | 38 | 89.14 | 2018-04-07 | 乂臲絖咭枿旂
68 | KWTRV | 60 | 71.40 | 2016-11-05 | 擨呮敻噣泪桢
69 | UAUSKREC | 70 | 78.12 | 2017-08-12 | 嚈鯁媬碿酷颧廷
70 | NXPFFR | 50 | 30.92 | 2019-04-01 | 撺鏈錒叜綱戋貁
71 | IMNZGQY | 40 | 15.27 | 2017-04-28 | 殎煙釀旃儶
72 | NSO | 81 | 78.04 | 2018-05-26 | 艾念孑
73 | MXYU | 39 | 48.53 | 2017-04-14 | 域裰停摵痮榼
74 | XEXYFL | 69 | 75.49 | 2018-10-05 | 夥椱垍欚皂
75 | VLIPU | 80 | 39.14 | 2018-03-13 | 垓瓷巜羀邳釠礢麊
76 | MFFEYLQ | 10 | 75.52 | 2017-04-29 | 挤圃撹藓瀪
77 | MFHYDKL | 33 | 1.15 | 2018-10-05 | 稔悮餱偨
78 | DFKNV | 49 | 29.87 | 2017-09-21 | 篇覰悡懵娶埝諁毩
79 | RNUDV | 83 | 35.63 | 2016-09-13 | 縐颷湃侃俺
80 | KOLXWC | 86 | 42.12 | 2017-03-20 | 蒲鰆庪
81 | IPDVL | 22 | 65.03 | 2018-09-24 | 茦肂尔簸伡嶗
82 | PPECNA | 14 | 35.96 | 2018-03-17 | 牳坈韥茝礖悊掄臃
83 | RVS | 94 | 43.71 | 2018-06-10 | 耡馌紉辸砙嶂
84 | RGXRK | 28 | 12.97 | 2018-06-18 | 懺拤河贏畮舶漭
85 | IHGHSP | 84 | 31.65 | 2017-12-24 | 堮兼缩祸蠜
86 | LKHSNPL | 77 | 85.98 | 2017-02-25 | 檱琺鯖限輯忂
87 | CXSX | 24 | 25.45 | 2018-07-19 | 智饔靻仰跬
88 | KBCYQ | 53 | 70.80 | 2017-12-25 | 捧閜酟徙豇
89 | LWRJQP | 60 | 86.94 | 2016-11-21 | 岇錬铄嵷腳徎绺蔘
90 | OIUG | 86 | 17.40 | 2018-01-02 | 且觜皟胾宒涺栨
91 | AXDWVC | 7 | 68.94 | 2016-10-22 | 梨寥鏏丛
92 | KIHQF | 46 | 16.69 | 2016-11-20 | 鞟炍咘厌遆
93 | PVISS | 17 | 79.24 | 2017-04-20 | 讯側帢馔陃帽涍
94 | NRXS | 12 | 9.89 | 2017-08-24 | 丣叟莽厮阥勘
95 | SKJKOE | 19 | 42.65 | 2016-11-18 | 腎鎱嚂醋
96 | KJXI | 8 | 2.69 | 2018-04-14 | 罞瀘辒捶症蘒桏
97 | KSNU | 27 | 68.46 | 2016-09-12 | 肒彾梞璞柿媄
98 | SNPAPQL | 33 | 24.84 | 2017-02-01 | 石榾邧鉁
99 | FOAAU | 70 | 0.92 | 2018-01-12 | 怿鈑蹾稿麔
100 | GMDHCT | 70 | 41.70 | 2019-05-16 | 竹禃雉毺氟泦
(100 rows)
作者：hemny
链接：https://www.jianshu.com/p/d465a4c748e8
来源：简书
简书著作权归作者所有，任何形式的转载都请联系作者获得授权并注明出处。
