Question

在MYSQL db中，我需要使用8到120之间的随机数来更新表“people”，但如果值介于103和109之间，我希望它变为110.

我该怎么做这样的查询？

UPDATE people SET column1 = '________random expression_________'

Answer 1

我没有测试过，但也许它应该可以工作。

UPDATE people 
SET column1 = (
    SELECT if(r.rand BETWEEN 103 AND 109, 110, r.rand)
    FROM ( SELECT floor(8+rand()*113) rand ) r
)

Answer 2

我写了一个Perl脚本来运行一个20k次的SQL查询，并且输出表明SELECTed值是正确的（显然，你只是想从脚本中解除和调整SQL来更新你的表，但是我包括了脚本，所以你可以证明它确实有效）：

#!/usr/bin/perl -w

use strict;
use DBI;
use Data::Dumper;

my $dbh = DBI->connect( "dbi:mysql:test", "root", "" ) or die $!;
my $q = <<EOQ;
select if(r.bar between 103 and 109, 110, r.bar )
 from ( select floor( rand() * 113 ) + 8 as bar ) r
EOQ
;
my $sth = $dbh->prepare( $q );
my $vals = {};
for ( 0 .. 20000 ) {
  $sth->execute();
  my $row = $sth->fetchrow_arrayref();
  my $int = $row->[0];
  $vals->{$int}++;
}
print join( "\n", sort keys %$vals ), "\n";

Answer 3

猜猜你总能做到

UPDATE people SET column1 =  floor(8+rand()*113)

UPDATE people 
SET column1 =  110
WHERE column1 BETWEEN 103 AND 109

或者其他似乎有效的方式，但肯定会更好。

UPDATE people 
SET column1 = 
(
SELECT rand FROM
(
SELECT 8 as rand UNION ALL
SELECT 9 as rand UNION ALL
SELECT 10 as rand UNION ALL
SELECT 11 as rand UNION ALL
SELECT 12 as rand UNION ALL
SELECT 13 as rand UNION ALL
SELECT 14 as rand UNION ALL
SELECT 15 as rand UNION ALL
SELECT 16 as rand UNION ALL
SELECT 17 as rand UNION ALL
SELECT 18 as rand UNION ALL
SELECT 19 as rand UNION ALL
SELECT 20 as rand UNION ALL
SELECT 21 as rand UNION ALL
SELECT 22 as rand UNION ALL
SELECT 23 as rand UNION ALL
SELECT 24 as rand UNION ALL
SELECT 25 as rand UNION ALL
SELECT 26 as rand UNION ALL
SELECT 27 as rand UNION ALL
SELECT 28 as rand UNION ALL
SELECT 29 as rand UNION ALL
SELECT 30 as rand UNION ALL
SELECT 31 as rand UNION ALL
SELECT 32 as rand UNION ALL
SELECT 33 as rand UNION ALL
SELECT 34 as rand UNION ALL
SELECT 35 as rand UNION ALL
SELECT 36 as rand UNION ALL
SELECT 37 as rand UNION ALL
SELECT 38 as rand UNION ALL
SELECT 39 as rand UNION ALL
SELECT 40 as rand UNION ALL
SELECT 41 as rand UNION ALL
SELECT 42 as rand UNION ALL
SELECT 43 as rand UNION ALL
SELECT 44 as rand UNION ALL
SELECT 45 as rand UNION ALL
SELECT 46 as rand UNION ALL
SELECT 47 as rand UNION ALL
SELECT 48 as rand UNION ALL
SELECT 49 as rand UNION ALL
SELECT 50 as rand UNION ALL
SELECT 51 as rand UNION ALL
SELECT 52 as rand UNION ALL
SELECT 53 as rand UNION ALL
SELECT 54 as rand UNION ALL
SELECT 55 as rand UNION ALL
SELECT 56 as rand UNION ALL
SELECT 57 as rand UNION ALL
SELECT 58 as rand UNION ALL
SELECT 59 as rand UNION ALL
SELECT 60 as rand UNION ALL
SELECT 61 as rand UNION ALL
SELECT 62 as rand UNION ALL
SELECT 63 as rand UNION ALL
SELECT 64 as rand UNION ALL
SELECT 65 as rand UNION ALL
SELECT 66 as rand UNION ALL
SELECT 67 as rand UNION ALL
SELECT 68 as rand UNION ALL
SELECT 69 as rand UNION ALL
SELECT 70 as rand UNION ALL
SELECT 71 as rand UNION ALL
SELECT 72 as rand UNION ALL
SELECT 73 as rand UNION ALL
SELECT 74 as rand UNION ALL
SELECT 75 as rand UNION ALL
SELECT 76 as rand UNION ALL
SELECT 77 as rand UNION ALL
SELECT 78 as rand UNION ALL
SELECT 79 as rand UNION ALL
SELECT 80 as rand UNION ALL
SELECT 81 as rand UNION ALL
SELECT 82 as rand UNION ALL
SELECT 83 as rand UNION ALL
SELECT 84 as rand UNION ALL
SELECT 85 as rand UNION ALL
SELECT 86 as rand UNION ALL
SELECT 87 as rand UNION ALL
SELECT 88 as rand UNION ALL
SELECT 89 as rand UNION ALL
SELECT 90 as rand UNION ALL
SELECT 91 as rand UNION ALL
SELECT 92 as rand UNION ALL
SELECT 93 as rand UNION ALL
SELECT 94 as rand UNION ALL
SELECT 95 as rand UNION ALL
SELECT 96 as rand UNION ALL
SELECT 97 as rand UNION ALL
SELECT 98 as rand UNION ALL
SELECT 99 as rand UNION ALL
SELECT 100 as rand UNION ALL
SELECT 101 as rand UNION ALL
SELECT 102 as rand UNION ALL
SELECT 110 as rand UNION ALL
SELECT 110 as rand UNION ALL
SELECT 110 as rand UNION ALL
SELECT 110 as rand UNION ALL
SELECT 110 as rand UNION ALL
SELECT 110 as rand UNION ALL
SELECT 110 as rand UNION ALL
SELECT 110 as rand UNION ALL
SELECT 111 as rand UNION ALL
SELECT 112 as rand UNION ALL
SELECT 113 as rand UNION ALL
SELECT 114 as rand UNION ALL
SELECT 115 as rand UNION ALL
SELECT 116 as rand UNION ALL
SELECT 117 as rand UNION ALL
SELECT 118 as rand UNION ALL
SELECT 119 as rand UNION ALL
SELECT 120 as rand

) T
ORDER BY rand()
LIMIT 1
)

Answer 4

update people 
   set `column1` = if ((@a := floor(8+rand()*113)) BETWEEN 103 AND 109 , 110, @a)
       ;

Answer 5

在代码中生成随机数，并将其传递给数据库。数据库专为处理数据而设计，并不是理想的选择。

UPDATE中的SQL随机值

5 个答案: