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Select name from syscolumns Where ID=OBJECT_ID('±íÃû')
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select * from information_schema.views
select * from information_schema.columns
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else '' end,
±í˵Ã÷ = case when a.colorder = 1 then isnull(f.value, '')
else '' end
from syscolumns a
inner join sysobjects d
on a.id = d.id
and d.xtype = 'U'
and d.name <> 'sys.extended_properties'
left join sys.extended_properties f
on a.id = f.major_id
and f.minor_id = 0
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systypes.name AS DATA_TYPE, syscolumns.length as CHARACTER_MAXIMUM_LENGTH,
sys.extended_properties.[value] AS COLUMN_DESCRIPTION, syscomments.text as
COLUMN_DEFAULT,syscolumns.isnullable as IS_NULLABLE from syscolumns
INNER JOIN systypes
ON syscolumns.xtype = systypes.xtype
LEFT JOIN sysobjects ON syscolumns.id = syso
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