select chr(int4(random()*26)+65);
postgres=# select chr(int4(random()*26)+65);
chr
-----
N
(1 row)
postgres=# select chr(int4(random()*26)+65);
chr
-----
Y
(1 row)
postgres=# select chr(int4(random()*26)+65);
chr
-----
N
(1 row)
postgres=# select chr(int4(random()*26)+65);
chr
-----
C
(1 row)
postgres=# select chr(int4(random()*26)+65);
chr
-----
O
(1 row)
postgres=# select chr(int4(random()*26)+65);
chr
-----
W
(1 row)
postgres=#
这个功能在造自己的测试数据时很有用:
postgres=# insert into test01 values(generate_series(1,10000000),repeat( chr(int4(random()*26)+65),4));
INSERT 0 10000000
postgres=#