Ruby: расширитесь сам

SELECT t.name AS 'table', i.name AS 'index', it.xtype,

(SELECT c.name FROM syscolumns c INNER JOIN sysindexkeys k 
    ON k.indid = i.indid 
        AND c.colid = k.colid 
        AND c.id = t.id 
        AND k.keyno = 1 
        AND k.id = t.id)
    AS 'column1',

(SELECT c.name FROM syscolumns c INNER JOIN sysindexkeys k 
    ON k.indid = i.indid 
        AND c.colid = k.colid 
        AND c.id = t.id 
        AND k.keyno = 2 
        AND k.id = t.id)
    AS 'column2',

(SELECT c.name FROM syscolumns c INNER JOIN sysindexkeys k 
    ON k.indid = i.indid 
        AND c.colid = k.colid 
        AND c.id = t.id 
        AND k.keyno = 3
        AND k.id = t.id)
    AS 'column3',

(SELECT c.name FROM syscolumns c INNER JOIN sysindexkeys k 
    ON k.indid = i.indid 
        AND c.colid = k.colid 
        AND c.id = t.id 
        AND k.keyno = 4
        AND k.id = t.id)
    AS 'column4',

(SELECT c.name FROM syscolumns c INNER JOIN sysindexkeys k 
    ON k.indid = i.indid 
        AND c.colid = k.colid 
        AND c.id = t.id 
        AND k.keyno = 5
        AND k.id = t.id)
    AS 'column5',

(SELECT c.name FROM syscolumns c INNER JOIN sysindexkeys k 
    ON k.indid = i.indid 
        AND c.colid = k.colid 
        AND c.id = t.id 
        AND k.keyno = 6
        AND k.id = t.id)
    AS 'column6',

(SELECT c.name FROM syscolumns c INNER JOIN sysindexkeys k 
    ON k.indid = i.indid 
        AND c.colid = k.colid 
        AND c.id = t.id 
        AND k.keyno = 7
        AND k.id = t.id)
    AS 'column7',

(SELECT c.name FROM syscolumns c INNER JOIN sysindexkeys k 
    ON k.indid = i.indid 
        AND c.colid = k.colid 
        AND c.id = t.id 
        AND k.keyno = 8 
        AND k.id = t.id)
    AS 'column8',

(SELECT c.name FROM syscolumns c INNER JOIN sysindexkeys k 
    ON k.indid = i.indid 
        AND c.colid = k.colid 
        AND c.id = t.id 
        AND k.keyno = 9 
        AND k.id = t.id)
    AS 'column9',

(SELECT c.name FROM syscolumns c INNER JOIN sysindexkeys k 
    ON k.indid = i.indid 
        AND c.colid = k.colid 
        AND c.id = t.id 
        AND k.keyno = 10
        AND k.id = t.id)
    AS 'column10',

FROM sysobjects t
    INNER JOIN sysindexes i ON i.id = t.id 
    INNER JOIN sysobjects it ON it.parent_obj = t.id AND it.name = i.name

WHERE it.xtype = 'PK'
ORDER BY t.name, i.name
113
задан Peter 14 November 2009 в 03:26
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2 ответа

It is a convenient way to make instance methods into class methods. But you can also use it as a more efficient singleton.

114
ответ дан 24 November 2019 в 02:43
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In a module, self is the module class itself. So for example

puts self

will return Rake so,

extend self

basically makes the instance methods defined in Rake available to it, so you can do

Rake.run_tests
29
ответ дан 24 November 2019 в 02:43
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