SQL DDL 生成建表语句(可自动生成主键约束，字段默认值等）

--获取建表DDL(+主键)
declare @tabname varchar(50)
set @tabname='sys_log'--表名
 
if ( object_id('tempdb.dbo.#t') is not null)
begin
DROP TABLE #t
end
 
select  'create table [' + so.name + '] (' + o.list + ')' 
    + CASE WHEN tc.Constraint_Name IS NULL THEN '' ELSE 'ALTER TABLE ' + so.Name + ' ADD CONSTRAINT ' + tc.Constraint_Name  + ' PRIMARY KEY ' + ' (' + LEFT(j.List, Len(j.List)-1) + ')' END 
    TABLE_DDL
into #t from    sysobjects so
cross apply
    (SELECT 
        '  ['+column_name+'] ' + 
        data_type + case data_type
            when 'sql_variant' then ''
            when 'text' then ''
            when 'ntext' then ''
            when 'xml' then ''
            when 'decimal' then '(' + cast(numeric_precision as varchar) + ', ' + cast(numeric_scale as varchar) + ')'
            else coalesce('('+case when character_maximum_length = -1 then 'MAX' else cast(character_maximum_length as varchar) end +')','') end + ' ' +
        case when exists ( 
        select id from syscolumns
        where object_name(id)=so.name
        and name=column_name
        and columnproperty(id,name,'IsIdentity') = 1 
        ) then
        'IDENTITY(' + 
        cast(ident_seed(so.name) as varchar) + ',' + 
        cast(ident_incr(so.name) as varchar) + ')'
        else ''
        end + ' ' +
         (case when IS_NULLABLE = 'No' then 'NOT ' else '' end ) + 'NULL ' + 
          case when information_schema.columns.COLUMN_DEFAULT IS NOT NULL THEN 'DEFAULT '+ information_schema.columns.COLUMN_DEFAULT ELSE '' END + ', ' 
 
     from information_schema.columns where table_name = so.name
     order by ordinal_position
    FOR XML PATH('')) o (list)
left join
    information_schema.table_constraints tc
on  tc.Table_name       = so.Name
AND tc.Constraint_Type  = 'PRIMARY KEY'
cross apply
    (select '[' + Column_Name + '], '
     FROM   information_schema.key_column_usage kcu
     WHERE  kcu.Constraint_Name = tc.Constraint_Name
     ORDER BY
        ORDINAL_POSITION
     FOR XML PATH('')) j (list)
where   xtype = 'U'
AND name=@tabname
 
select 'USE '+db_name() +CHAR(13) +'GO' + CHAR(13) +
(--区别有主键和没主键
case when (select count(a.constraint_type)
from information_schema.table_constraints a 
inner join information_schema.constraint_column_usage b
on a.constraint_name = b.constraint_name
where a.constraint_type = 'PRIMARY KEY'--主键 
and a.table_name = @tabname)=1 then
replace(table_ddl,', )ALTER TABLE',')'+CHAR(13)+'ALTER TABLE')
else SUBSTRING(table_ddl,1,len(table_ddl)-3)+')' end
) from #t
 
--drop table #t
 
-- SP_HELP sys_log

生成的效果如下：

CREATE TABLE [Sys_Log] (
    [LSTime] datetime  NOT NULL DEFAULT (getdate()),   
	[LOptName] char(10)  NULL ,   
	[LOptType] char(12)  NULL ,   
	[LOptObj] char(20)  NULL ,   
	[LDetail] varchar(120)  NULL ,   
	[LStation] tinyint  NULL ,   
	[LCopied] tinyint  NULL DEFAULT ('0'),   
	[VTimeStamp] timestamp  NOT NULL 
)ALTER TABLE Sys_Log ADD CONSTRAINT PK__Sys_Log__8E0F0ACB1FCDBCEB PRIMARY KEY  ([LSTime])

可自动生成主键约束，及默认值