一、概述

       在軟體實施過程中，我遇到了這麼一個問題，我在客戶那邊安裝了整個ERP程式並且向資料庫中匯入了客戶提供給我的基礎資料，程式進入試執行階段，在試執行期間，客戶反映出程式的各種問題，需要提交給公司去糾正這些問題，在糾正問題的時候伴隨的問題的解決，程式開發人員向資料庫中添加了資料庫表或者向已有表中添加了欄位，這個時候開發員沒有一個良好的習慣用SQL語法來操作這些新增，而是直接在資料庫設計器中新增，在實施人員給客戶更新程式的時候需要重新還原資料庫，導致之前已經匯入的基礎資料需要重新做處理，做了重複工作量，我作為一個實施人員為了讓自己工作更輕鬆，編寫了這麼一個小工具，網上搜索了一下，很多這種的小工具但是並不適合我，自己動手豐衣足食，接下來我們探討一下這個小工具的實現。

二、小工具設計思路

      需要兩個資料庫進行比較，那麼我們需要兩個不同的資料庫甚至連線兩個不同的資料庫伺服器，針對不同的資料庫伺服器中的兩個資料庫進行表結構比對（大家可以考慮儲存過程，函式等的比對，比對過程都不會難），想到這些我們就可以開始著手開始設計程式了，設計介面如下圖所示：

三、程式設計

獲取表結構的SQL語法：

USE DBName--換成你自己的資料庫名稱

SELECT distinct 表名 = OBJECT_NAME(c.object_id),
                    表描述 = (SELECT top 1 a.[value] FROM sys.extended_properties a left JOIN  sysobjects b ON a.major_id=b.id WHERE b.name=OBJECT_NAME(c.object_id) and a.minor_id=0 ),
                    欄位名 = c.name, 欄位描述 = ex.value, 欄位型別 = t.name, 欄位長度 = c.max_length, 位數 = c.precision, 小數位 = c.scale
                    FROM sys.columns c LEFT OUTER JOIN sys.extended_properties ex
                    ON ex.major_id = c.object_id AND ex.minor_id = c.column_id AND ex.name = 'MS_Description'
                    left outer join systypes t on c.system_type_id = t.xtype WHERE
                    OBJECTPROPERTY(c.object_id, 'IsMsShipped') = 0 AND
                    t.name != 'sysname'

編寫一個方法放入上述SQL 返回一個datatable。

獲取資料庫中表的建立語法：

USE DBName--此處替換為你自己的資料庫名稱

SET ARITHABORT ON
SET CONCAT_NULL_YIELDS_NULL ON
SET QUOTED_IDENTIFIER ON
SET ANSI_NULLS ON
SET ANSI_PADDING ON
SET ANSI_WARNINGS ON
SET NUMERIC_ROUNDABORT OFF

declare @crlf char(2)
SET @crlf=char(13)+char(10)

;WITH ColumnDefs as
(
    select TableObj=c.[object_id]
        ,ColSeq=c.column_id
        ,ColumnDef=quotename(c.Name)+' '
                    +case
                        when c.is_computed=1 then 'as '+coalesce(k.[definition],'')
                            +case when k.is_persisted=1 then ' PERSISTED'+case when k.is_nullable=0 then ' NOT NULL' else '' end else '' end
                        else DataType
                            +case
                            when DataType in ('decimal','numeric') then '('+cast(c.precision as varchar(10))+case when c.scale<>0 then ','+cast(c.scale as varchar(10)) else '' end +')'
                            when DataType in ('char','varchar','nchar','nvarchar','binary','varbinary') then '('+case when c.max_length=-1 then 'max' else case when DataType in ('nchar','nvarchar') then cast(c.max_length/2 as varchar(10)) else cast(c.max_length as varchar(10)) end end +')'
                            when DataType='float' and c.precision<>53 then '('+cast(c.precision as varchar(10))+')'
                            when DataType in ('time','datetime2','datetimeoffset') and c.scale<>7 then '('+cast(c.scale as varchar(10))+')'
                            else ''
                            end
                    end
                    +case when c.is_identity=1 then ' IDENTITY('+cast(IDENT_SEED(quotename(object_schema_name(c.[object_id]))+'.'+quotename(object_name(c.[object_id]))) as varchar(30))+','+cast(ident_incr(quotename(object_schema_name(c.[object_id]))+'.'+quotename(object_name(c.[object_id]))) as varchar(30))+')' else '' end
                    +case when c.is_rowguidcol=1 then ' ROWGUIDCOL' else '' end
                    +case when c.xml_collection_id>0 THEN ' (CONTENT '+QUOTENAME(SCHEMA_NAME(x.SCHEMA_ID))+'.'+ QUOTENAME(x.name)+')' ELSE '' end
                    +case
                        when c.is_computed=0 and UserDefinedFlag=0
                        then case
                            when c.collation_name<>cast(databasepropertyex(db_name() ,'collation') as nvarchar(128))
                            then ' COLLATE '+c.collation_name
                            else ''
                            end
                        else ''
                    end
                    +case when c.is_computed=0 then case when c.is_nullable=0 then ' NOT' else '' end+' NULL' else '' end
                    +case
                        when c.default_object_id>0
                        then ' CONSTRAINT '+quotename(d.name)+' DEFAULT '+coalesce(d.[definition],'')
                        else ''
                    end
                
    from sys.columns c
    cross apply ( 
    select DataType=type_name(c.user_type_id)
            ,UserDefinedFlag=case
                                when c.system_type_id=c.user_type_id
                                then 0
                                else 1
                                end) F1
    left join sys.default_constraints d ON c.default_object_id=d.[object_id]
    left join sys.computed_columns k ON c.[object_id]=k.[object_id]
                                    and c.column_id=k.column_id
    left join  sys.xml_schema_collections x ON c.xml_collection_id = x.xml_collection_id                           
)
,IndexDefs as
(
    select TableObj=i.[object_id]
        ,IxName=quotename(i.name)
        ,IxPKFlag=i.is_primary_key
        ,IxType=case when i.is_primary_key=1 then 'PRIMARY KEY ' when i.is_unique=1 then 'UNIQUE ' else '' end
                +lower(type_desc)
        ,IxDef='('+IxColList+')'
                +coalesce(' INCLUDE ('+IxInclList+')','')
        ,IxOpts=IxOptList       
    from sys.indexes i
    left join sys.stats s ON i.index_id=s.stats_id and i.[object_id]=s.[object_id]
    cross apply ( 
    select stuff((select case when i.is_padded=1 then ', PAD_INDEX=ON' else '' end
                        +case when i.fill_factor<>0 then ', FILLFACTOR='+cast(i.fill_factor as varchar(10)) else '' end
                        +case when i.ignore_dup_key=1 then ', IGNORE_DUP_KEY=ON' else '' end
                        +case when s.no_recompute=1 then ', STATISTICS_RECOMPUTE=ON' else '' end
                        +case when i.allow_row_locks=0 then ', ALLOW_ROW_LOCKS=OFF' else '' end
                        +case when i.allow_page_locks=0 then ', ALLOW_PAGE_LOCKS=OFF' else '' end)
                    ,1,2,'')) F_IxOpts(IxOptList)
    cross apply ( 
    select stuff((select ','+quotename(c.name)
                        +case
                            when ic.is_descending_key=1 AND i.type<>3
                            then ' DESC'
                            WHEN ic.is_descending_key=0 AND i.type<>3
                            THEN ' ASC'
                            ELSE ''
                            end
                    from sys.index_columns ic
                    join sys.columns c ON ic.[object_id]=c.[object_id]
                                        and ic.column_id=c.column_id
                    where ic.[object_id]=i.[object_id]
                    and ic.index_id=i.index_id
                    and ic.is_included_column=0
                    order by ic.key_ordinal
                    FOR xml path(''),type).value('.','nvarchar(max)')
                ,1,1,'')) F_IxCols(IxColList)
    cross apply ( 
    select stuff((select ','+quotename(c.name)
                    from sys.index_columns ic
                    join sys.columns c ON ic.[object_id]=c.[object_id]
                                        and ic.column_id=c.column_id
                    where ic.[object_id]=i.[object_id]
                    and ic.index_id=i.index_id
                    and ic.is_included_column=1
                    order by ic.key_ordinal
                    FOR xml path(''),type).value('.','nvarchar(max)')
                ,1,1,'')) F_IxIncl(IxInclList)
    where i.type_desc<>'HEAP'
)
,FKDefs as
(
    select TableObj=f.parent_object_id
        ,FKName=quotename(f.name)
        ,FKRef=quotename(object_schema_name(f.referenced_object_id))+'.'
                +quotename(object_name(f.referenced_object_id))
        ,FKColList=ParentColList
        ,FKRefList=RefColList
        ,FKDelOpt=case f.delete_referential_action
                    when 1 then 'CASCADE'
                    when 2 then 'SET NULL'
                    when 3 then 'SET DEFAULT'
                    end
        ,FKUpdOpt=case f.update_referential_action
                    when 1 then 'CASCADE'
                    when 2 then 'SET NULL'
                    when 3 then 'SET DEFAULT'
                    end
        ,FKNoRepl=f.is_not_for_replication
    from sys.foreign_keys f
    cross apply ( 
    select stuff((select ','+quotename(c.name)
                    from sys.foreign_key_columns k
                    join sys.columns c ON k.parent_object_id=c.[object_id]
                                        and k.parent_column_id=c.column_id
                    where k.constraint_object_id=f.[object_id]
                    order by constraint_column_id
                    FOR xml path(''),type).value('.','nvarchar(max)')
                ,1,1,'')) F_Parent(ParentColList)
    cross apply (
    select stuff((select ','+quotename(c.name)
                    from sys.foreign_key_columns k
                    join sys.columns c ON k.referenced_object_id=c.[object_id]
                                        and k.referenced_column_id=c.column_id
                    where k.constraint_object_id=f.[object_id]
                    order by constraint_column_id
                    FOR xml path(''),type).value('.','nvarchar(max)')
                ,1,1,'')) F_Ref(RefColList)
)
select TableName
        ,[definition]
from sys.tables t
cross apply ( 
    select TableName=quotename(object_schema_name(t.[object_id]))+'.'
                    +quotename(object_name(t.[object_id]))) F_Name
cross apply (
    select stuff((select @crlf+'  ,'+ColumnDef
                from ColumnDefs
                where TableObj=t.[object_id]
                order by ColSeq
                FOR xml path(''),type).value('.','nvarchar(max)')
                ,1,5,'')) F_Cols(ColumnList)
cross apply (
    select stuff((select @crlf+'  ,CONSTRAINT '+quotename(name)+' CHECK '
                        +case when is_not_for_replication=1 then 'NOT FOR REPLICATION ' else '' end
                        +coalesce([definition],'')
                from sys.check_constraints
                where parent_object_id=t.[object_id]
                FOR xml path(''),type).value('.','nvarchar(max)')
                ,1,2,'')) F_Const(ChkConstList)
cross apply (
    select stuff((select @crlf+'  ,CONSTRAINT '+IxName+' '+IxType+' '+IxDef+coalesce(' WITH ('+IxOpts+')','')
                from IndexDefs
                where TableObj=t.[object_id]
                    and IxPKFlag=1
                FOR xml path(''),type).value('.','nvarchar(max)')
                ,1,2,'')) F_IxConst(IxConstList)
cross apply (
    select stuff((select @crlf+'  ,CONSTRAINT '+FKName+' FOREIGN KEY '+'('+FKColList+')'+' REFERENCES '+FKRef+' ('+FKRefList+')'
                        +case when FKDelOpt is NOT NULL then ' ON DELETE '+FKDelOpt else '' end
                        +case when FKUpdOpt is NOT NULL then ' ON UPDATE '+FKUpdOpt else '' end
                        +case when FKNoRepl=1 then ' NOT FOR REPLICATION' else '' end
                from FKDefs
                where TableObj=t.[object_id]
                FOR xml path(''),type).value('.','nvarchar(max)')
                ,1,2,'')) F_Keys(FKConstList)
cross apply (
    select stuff((select @crlf+'CREATE '+IxType+' INDEX '+IxName+' ON '+TableName+' '+IxDef+coalesce(' WITH ('+IxOpts+')','')
                from IndexDefs
                where TableObj=t.[object_id]
                    and IxPKFlag=0
                FOR xml path(''),type).value('.','nvarchar(max)')
                ,1,2,'')) F_Indexes(IndexList)
cross apply (
    select [definition]=(select 'CREATE TABLE

'[email protected]+'('[email protected]+'   '+ColumnList+coalesce(@crlf+ChkConstList,'')+coalesce(@crlf+IxConstList,'')+coalesce(@crlf+FKConstList,'')[email protected]+')'+coalesce(@crlf+IndexList,'')[email protected]
    FOR xml path(''),type).value('.','nvarchar(max)')) F_Link

這個SQL語法是網上某位大神的，我收藏了很久了都忘記在哪裡了，這裡不能提供出處，望見諒。

在此處也一樣的編寫一個方法來執行上述SQL 返回一個datatable

做好上述準備以後我們就可以來實現 表結構比對方法了，此時我們需要考慮一下幾點：

1.目標資料庫中無來源資料庫中表的情況下，獲取建立表語法

2.目標資料庫中存在來源資料庫中表的情況下，進行表字段比較

3.綜合第2點，目標資料表中無來源資料表中的欄位，則在目標資料表中新增來源表的欄位

滿足上述這些要求我們就可以設計出一個比對方法了。接下來提供資料庫表字段的新增SQL語法和欄位描述的SQL語法如下：

--新增資料庫欄位的語法

strbSQLScript.Append("IF NOT EXISTS(select * from syscolumns where id=object_id('" + dr["表名"].ToString() + "') and name='" + dr["欄位名"].ToString() + "') \r\n");
                            strbSQLScript.Append("Alter table " + dr["表名"].ToString() + " Add " + dr["欄位名"].ToString() + " " + dr["欄位型別"].ToString() + "(" + dr["欄位長度"].ToString() + ") null \r\n");
                            strbSQLScript.Append("GO \r\n");

--新增資料庫欄位描述的語法
                            strbSQLScript.Append("IF NOT EXISTS (SELECT * FROM ::fn_listextendedproperty(N'MS_Description' , N'SCHEMA',N'dbo', N'TABLE',N'" + dr["表名"].ToString() + "', N'COLUMN',N'" + dr["欄位名"].ToString() + "')) \r\n");
                            strbSQLScript.Append("EXEC sys.sp_addextendedproperty @name=N'MS_Description', @value=N'" + dr["欄位描述"].ToString() + "' , @level0type=N'SCHEMA',@level0name=N'dbo', @level1type=N'TABLE',@level1name=N'" + dr["表名"].ToString() + "', @level2type=N'COLUMN',@level2name=N'" + dr["欄位名"].ToString() + "' \r\n");
                            strbSQLScript.Append("GO \r\n");

這兩個語法我直接放程式碼上來了，我用的foreach迴圈。