SQL DDL 生成建表语句(可自动生成主键约束，字段默认值等）

心已赠人 2023-10-04 13:10 7阅读 0赞

--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])

![20210511234716351.png][]

**可自动生成主键约束，及默认值**

[20210511234716351.png]: https://img-blog.csdnimg.cn/20210511234716351.png