问题
I'm trying to compute a checksum or a hash for an entire table in SQL Server 2008. The problem I'm running into is that the table contains an XML column datatype, which cannot be used by checksum and has to be converted to nvarchar first. So I need to break it down into two problems:
- calculate a checksum for a row, schema is unknown before runtime.
- calculate the checksum for all of the rows to get the full table checksum.
回答1:
You can use CHECKSUM_AGG. It only takes a single argument, so you could do CHECKSUM_AGG(CHECKSUM(*)) - but this doesn't work for your XML datatype, so you'll have to resort to dynamic SQL.
You could generate dynamically the column list from INFORMATION_SCHEMA.COLUMNS and then insert int into a template:
SELECT @column_list = COALESCE(@column_list + ', ', '')
+ /* Put your casting here from XML, text, etc columns */ QUOTENAME(COLUMN_NAME)
FROM INFORMATION_SCHEMA.COLUMNS
WHERE TABLE_NAME = @table_name
AND TABLE_SCHEMA = @schema_name
DECLARE @template AS varchar(MAX)
SET @template = 'SELECT CHECKSUM_AGG(CHECKSUM({@column_list})) FROM {@schema_name}.{@table_name}'
DECLARE @sql AS varchar(MAX)
SET @sql = REPLACE(REPLACE(REPLACE(@template
'{@column_list}', @column_list),
'{@schema_name}', @schema_name),
'{@table_name}', @table_name)
EXEC ( @sql )
回答2:
I modified the script to generate a query for all relevant tables in a database.
USE myDatabase
GO
DECLARE @table_name sysname
DECLARE @schema_name sysname
SET @schema_name = 'dbo'
DECLARE myCursor cursor
FOR SELECT TABLE_NAME
FROM INFORMATION_SCHEMA.TABLES T
WHERE T.TABLE_SCHEMA = @schema_name
AND T.TABLE_TYPE = 'BASE TABLE'
AND T.TABLE_NAME NOT LIKE 'MSmerge%'
AND T.TABLE_NAME NOT LIKE 'sysmerge%'
AND T.TABLE_NAME NOT LIKE 'tmp%'
ORDER BY T.TABLE_NAME
OPEN myCursor
FETCH NEXT
FROM myCursor
INTO @table_name
WHILE @@FETCH_STATUS = 0
BEGIN
DECLARE @column_list nvarchar(MAX)
SET @column_list=''
SELECT @column_list = @column_list + CASE WHEN DATA_TYPE IN ('xml','text','ntext','image sql_variant') THEN 'CONVERT(nvarchar(MAX),'
ELSE ''
END
+ QUOTENAME(COLUMN_NAME)
+ CASE WHEN DATA_TYPE IN ('xml','text','ntext','image sql_variant') THEN ' /* ' + DATA_TYPE + ' */)'
ELSE ''
END + ', '
FROM INFORMATION_SCHEMA.COLUMNS
WHERE TABLE_NAME = @Table_name
ORDER BY ORDINAL_POSITION
SET @column_list = LEFT(@column_list, LEN(@column_list)-1) -- remove trailing comma
DECLARE @sql AS nvarchar(MAX)
SET @sql = 'SELECT ''' + QUOTENAME(@schema_name) + '.' + QUOTENAME(@table_name) + ''' table_name,
CHECKSUM_AGG(CHECKSUM(' + @column_list + ')) CHECKSUM
FROM ' + QUOTENAME(@schema_name) + '.' + QUOTENAME(@Table_name) + ' WITH (NOLOCK)'
PRINT @sql
FETCH NEXT
FROM myCursor
INTO @table_name
IF @@FETCH_STATUS = 0
PRINT 'UNION ALL'
END
CLOSE myCursor
DEALLOCATE myCursor
GO
回答3:
//Quick hash sum of SQL and C # mirror Ukraine //HASH_ZKCRC64 ///-------------------------------------------------------------------------------------------------------------- private Int64 HASH_ZKCRC64(byte[] Data) { Int64 Result = 0x5555555555555555; if (Data == null || Data.Length <= 0) return 0; int SizeGlobalBufer = 8000; int Ost = Data.Length % SizeGlobalBufer; int LeftLimit = (Data.Length / SizeGlobalBufer) * SizeGlobalBufer;
for (int i = 0; i < LeftLimit; i += 64)
{
Result = Result
^ BitConverter.ToInt64(Data, i)
^ BitConverter.ToInt64(Data, i + 8)
^ BitConverter.ToInt64(Data, i + 16)
^ BitConverter.ToInt64(Data, i + 24)
^ BitConverter.ToInt64(Data, i + 32)
^ BitConverter.ToInt64(Data, i + 40)
^ BitConverter.ToInt64(Data, i + 48)
^ BitConverter.ToInt64(Data, i + 56);
if ((Result & 0x0000000000000080) != 0)
Result = Result ^ BitConverter.ToInt64(Data, i + 28);
}
if (Ost > 0)
{
byte[] Bufer = new byte[SizeGlobalBufer];
Array.Copy(Data, LeftLimit, Bufer, 0, Ost);
for (int i = 0; i < SizeGlobalBufer; i += 64)
{
Result = Result
^ BitConverter.ToInt64(Bufer, i)
^ BitConverter.ToInt64(Bufer, i + 8)
^ BitConverter.ToInt64(Bufer, i + 16)
^ BitConverter.ToInt64(Bufer, i + 24)
^ BitConverter.ToInt64(Bufer, i + 32)
^ BitConverter.ToInt64(Bufer, i + 40)
^ BitConverter.ToInt64(Bufer, i + 48)
^ BitConverter.ToInt64(Bufer, i + 56);
if ((Result & 0x0000000000000080)!=0)
Result = Result ^ BitConverter.ToInt64(Bufer, i + 28);
}
}
byte[] MiniBufer = BitConverter.GetBytes(Result);
Array.Reverse(MiniBufer);
return BitConverter.ToInt64(MiniBufer, 0);
#region SQL_FUNCTION
/* CREATE FUNCTION [dbo].[HASH_ZKCRC64] (@data as varbinary(MAX)) Returns bigint
AS
BEGIN
Declare @I64 as bigint Set @I64=0x5555555555555555
Declare @Bufer as binary(8000)
Declare @i as int Set @i=1
Declare @j as int
Declare @Len as int Set @Len=Len(@data)
if ((@data is null) Or (@Len<=0)) Return 0
While @i<=@Len
Begin
Set @Bufer=Substring(@data,@i,8000)
Set @j=1
While @j<=8000
Begin
Set @I64=@I64
^ CAST(Substring(@Bufer,@j, 8) as bigint)
^ CAST(Substring(@Bufer,@j+8, 8) as bigint)
^ CAST(Substring(@Bufer,@j+16,8) as bigint)
^ CAST(Substring(@Bufer,@j+24,8) as bigint)
^ CAST(Substring(@Bufer,@j+32,8) as bigint)
^ CAST(Substring(@Bufer,@j+40,8) as bigint)
^ CAST(Substring(@Bufer,@j+48,8) as bigint)
^ CAST(Substring(@Bufer,@j+56,8) as bigint)
if @I64<0 Set @I64=@I64 ^ CAST(Substring(@Bufer,@j+28,8) as bigint)
Set @j=@j+64
End;
Set @i=@i+8000
End
Return @I64
END
*/
#endregion
}
来源：https://stackoverflow.com/questions/1560306/calculate-hash-or-checksum-for-a-table-in-sql-server