如何比较多个数据库中的数据
我正在尝试比较来自多个数据库的一些数据，正如我已经说明的当前情况一样，我那里有数据库，数据库1是主要数据库，并且不时地从数据库1更新了数据库2和数据库3。我很难获得最终结果，该最终结果从数据库1返回数据，并且两列列显示数据库2的可用性为“是”或“否”，第二个额外列也是如此，这将表明数据库3的数据可用性为“是”或者没有。
SELECT *
FROM (
Select ID as db1_ID,
First_name as db1_First_name,
Last_name as db1_Last_name,
Email as db1_Email,
Password as db1_Password,
Request_Id as db1_Request_Id,
User_Id as db1_User_Id,
Request_name as db1_Request_name
from User
inner join User_request
on User_request.User_Id = user.ID
) AS DB1_VIEW
LEFT OUTER JOIN
(
Select ID as db2_ID,
First_name as db2_First_name,
Last_name as db2_Last_name,
Email as db2_Email,
Password as db2_Password,
Request_Id as db2_Request_Id,
User_Id as db2_User_Id,
Request_name as db2_Request_name
from User
inner join User_request
on User_request.User_Id = user.ID
) AS DB2_VIEW
ON db2_ID = db1_ID
LEFT OUTER JOIN
(
Select ID as db3_ID,
First_name as db3_First_name,
Last_name as db3_Last_name,
Email as db3_Email,
Password as db3_Password,
Request_Id as db3_Request_Id,
User_Id as db3_User_Id,
Request_name as db3_Request_name
from User
inner join User_request
on User_request.User_Id = user.ID
) AS DB3_VIEW
ON db3_ID = db1_ID
ID First_name Last_name Email Password Request_Id User_Id Request_name
1 Oliver Jake OJake@domain.com 123 1 1 Request1
2 Mathew Harry MHarry@domain.com 123 1 2 Request1
3 Jacob Reece JReece@domain.com 123 1 3
Request1
4 Charlie Damian CDamian@domain.com 123 1 4 Request1
3 个答案:
答案 0 :(得分：1)
将此作为您的第一条选择语句：
SELECT DB1_VIEW.*
,CASE WHEN DB2_VIEW.db2_ID IS NOT NULL THEN 'Y' ELSE 'N' END AS Available_db2
,CASE WHEN DB3_VIEW.db3_ID IS NOT NULL THEN 'Y' ELSE 'N' END AS Available_db3
您可以除去db2_view和db3_view子查询中的ID字段之外的所有详细信息。
答案 1 :(得分：1)
您可以在执行之前使用以下查询，您应该将[SourceDB]替换为源数据库，将[TargertDB]替换为目标数据库。将表名称插入#mdtables中以供比较。
USE [SourceDB]
IF Object_id('tempdb..#mdTables') IS NOT NULL
DROP TABLE #mdtables;
CREATE TABLE #mdtables
(
id INT IDENTITY(1, 1) NOT NULL,
schemaname NVARCHAR(128),
tablename NVARCHAR(128)
);
INSERT INTO #mdtables
(schemaname,
tablename)
VALUES ('dbo',
'user');
DECLARE @mdTableLim INT =0,
@mdTableRowId INT =0
SELECT @mdTableLim = Count(*)
FROM #mdtables;
SET @mdTableRowId = 1;
WHILE @mdTableRowId <= @mdTableLim
BEGIN
DECLARE @SDBName VARCHAR(50) = '[SourceDB]',
@TDBName VARCHAR(50) = '[TargertDB]',
@tableName VARCHAR(100) = ''
DECLARE @WhereF VARCHAR(max) ='',
@joincondition VARCHAR(max) ='',
@or VARCHAR(10) ='',
@select VARCHAR(max) = '',
@comma VARCHAR(1)='',
@query VARCHAR(max) ='',
@and VARCHAR(5)='',
@where1 VARCHAR(1000) ='',
@wOR VARCHAR(5)=''
SELECT @tableName = tablename
FROM #mdtables
WHERE id = @mdTableRowId;
SELECT @joincondition += Isnull(@and + ( CASE
WHEN cu.column_name IS NULL
THEN
NULL
ELSE ' src.[' + cu.column_name
+
'] = ' +
'trgt.['
+ c.column_name + ']'
END ), ''),
@WhereF += Isnull (@or + ( CASE
WHEN cu.column_name IS NOT NULL THEN
NULL
ELSE Isnull ( ' src.[' +
TC.column_name
+
'] ',
' isnull( src.[' +
C.column_name +
'],1) ' )
+ Isnull( '<> trgt.[' +
TC.column_name
+ ']',
' = isnull (src.['
+
C.column_name + '],1) ')
END ), ''),
@or = ( CASE
WHEN cu.column_name IS NOT NULL THEN ''
ELSE ' OR '
END ),
@and = ( CASE
WHEN cu.column_name IS NULL THEN ''
ELSE ' AND '
END ),
@select += @comma + ' src.[' + c.column_name + '] '
+ Isnull (' , trgt.[' + TC.column_name + ']', ''),
@comma = ',',
@where1 += Isnull(( @wOR + ( CASE
WHEN cu.column_name IS NULL THEN
NULL
ELSE ' trgt.[' + cu.column_name +
'] is null '
END ) ), ''),
@wOR = ( CASE
WHEN cu.column_name IS NULL THEN ''
ELSE ' OR '
END )
FROM information_schema.columns C
LEFT JOIN information_schema.key_column_usage CU
ON C.column_name = cu.column_name
AND constraint_name LIKE 'PK_%'
AND c.table_name = cu.table_name
LEFT JOIN [TargertDB].information_schema.columns TC
ON C.column_name = TC.column_name
AND c.table_name = TC.table_name
WHERE c.table_name = @tableName
--AND columnproperty(object_id(TABLE_NAME), COLUMN_NAME, 'IsIdentity') = 0
AND c.column_name NOT IN ( 'LST_CHG_TMS', 'LST_CHG_TMS',
'LST_CHG_USR_ID'
,
'LST_CHG_USR_ID' )
AND c.data_type NOT IN ( 'image' )
ORDER BY cu.column_name
SET @query = 'select ' + @select + ' from ' + @SDBName + '.dbo.'
+ @tableName + ' as src left join ' + @TDBName
+ '.dbo.' + @tableName + ' as trgt on '
+ @joincondition + ' where (' + @where1 + ')'
+ Isnull ('and '+ NULLIF (@WhereF, ''), '')
DECLARE @qu1 VARCHAR(max) =
' declare @cnt int =0 select @cnt =count (1) from '
+ @SDBName + '.dbo.' + @tableName
+ ' as src left join ' + @TDBName + '.dbo.'
+ @tableName + ' as trgt on ' + @joincondition
+ ' where (' + @where1 + ')'
+ Isnull (' OR '+ NULLIF (@WhereF, ''), '')
+ ' if (@cnt>0) begin select '''
+ @tableName + ''' as [ ],@cnt ' +-- @query + ' end '
BEGIN try
EXECUTE ( @qu1)
END try
BEGIN catch
PRINT @qu1;
END catch
SET @mdTableRowId = @mdTableRowId + 1
END
答案 2 :(得分：0)
这可能不需要CTE或子查询。 可以加入一些联接。
SELECT
Usr1.ID AS db1_User_Id,
Usr1.First_name AS db1_First_name,
Usr1.Last_name AS db1_Last_name,
Usr1.Email AS db1_Email,
Usr1.Password AS db1_Password,
MAX(UsrReq1.Request_Id) AS db1_Request_Id,
MAX(UsrReq1.Request_name) AS db1_Request_name,
CASE WHEN COUNT(UsrReq2.User_Id) > 0 THEN 'Y' ELSE 'N' END AS Available_Db2,
CASE WHEN COUNT(UsrReq3.User_Id) > 0 THEN 'Y' ELSE 'N' END AS Available_Db3
FROM [Database1].[User] AS Usr1
LEFT JOIN [Database1].[User_request] AS UsrReq1 ON UsrReq1.User_Id = Usr1.ID
LEFT JOIN [Database2].[User] AS Usr2 ON Usr2.ID = Usr1.ID
LEFT JOIN [Database2].[User_request] AS UsrReq2 ON UsrReq2.User_Id = Usr2.ID
LEFT JOIN [Database3].[User] AS Usr3 ON Usr3.ID = Usr1.ID
LEFT JOIN [Database3].[User_request] AS UsrReq3 ON UsrReq3.User_Id = Usr3.ID
GROUP BY
Usr1.ID,
Usr1.First_name,
Usr1.Last_name,
Usr1.Email,
Usr1.Password;
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