来自多个数据库的 SQL - Select

Question

我有 10 个数据库，它们都在同一个实例和模式中，具有相同的表。

希望创建一个SELECT查询，它可以使用数据库名称的变量并将所有记录返回到单个数据集中。

我一直在环顾四周并将以下内容放在一起作为测试（真实的 select 语句要大得多，有多个连接）

该测试确实有效，但它返回两个结果集，每个数据库一个。

有没有办法将结果合并为一组，还是我使用了错误的方法？

提前致谢

DECLARE @DB_NAME VARCHAR(6);

DECLARE CURSOR_ALLDB_NAMES CURSOR FOR 
    SELECT name
    FROM sys.databases
    WHERE name IN ('CN2DAT', 'AU1DAT') 

OPEN CURSOR_ALLDB_NAMES

FETCH NEXT FROM CURSOR_ALLDB_NAMES INTO @DB_NAME

WHILE @@Fetch_Status = 0
BEGIN
    EXEC ('SELECT * FROM ' + @DB_NAME + '.dbo.ICITEM')

    -- EXEC ('USE '+ @DB_NAME + ' SELECT * from dbo.ICITEM')

    FETCH NEXT FROM CURSOR_ALLDB_NAMES INTO @DB_NAME
END

CLOSE CURSOR_ALLDB_NAMES
DEALLOCATE CURSOR_ALLDB_NAMES

Answer 1

我会创建一个结合了 select 语句的视图。 例如

CREATE VIEW v_ICITEM
AS
SELECT * FROM CN2DAT.dbo.ICITEM
UNION ALL 
SELECT * FROM AU1DAT.dbo.ICITEM
go;

您也可以将源数据库作为列包括在内：

CREATE VIEW v_ICITEM
AS
SELECT 'CN2DAT' AS Db, * FROM CN2DAT.dbo.ICITEM
UNION ALL 
SELECT 'AU1DAT', * FROM AU1DAT.dbo.ICITEM
go;

Answer 2

将结果存储到临时表中，例如：

CREATE TABLE #TempICITEM 
    ([DbName] [varchar](6) NOT NULL,
    [ICITEMId] [uniqueidentifier] NOT NULL,
    [Name] [varchar](100) NOT NULL,
    [Description] [varchar](1000) NOT NULL)

将您的 TSQL select 更改为 Insert Into #TempTable Select 例如：

EXEC ('INSERT INTO #TempICITEM ([DbName],[ICITEMId],[Name],[Description]) SELECT ''' + @DB_NAME + ''' DbName,[DbName],[ICITEMId],[Name],[Description] FROM ' + @DB_NAME + '.dbo.ICITEM')

然后 Select 来自临时表的组合结果，例如：

SELECT * From #TempICITEM

一起：

CREATE TABLE #TempICITEM 
    ([DbName] [varchar](6) NOT NULL,
    [ICITEMId] [uniqueidentifier] NOT NULL,
    [Name] [varchar](100) NOT NULL,
    [Description] [varchar](1000) NOT NULL)

DECLARE @DB_NAME VARCHAR(6);
DECLARE CURSOR_ALLDB_NAMES CURSOR FOR 
SELECT name
FROM sys.databases
WHERE name IN ('CN2DAT', 'AU1DAT') 

OPEN CURSOR_ALLDB_NAMES
FETCH NEXT FROM CURSOR_ALLDB_NAMES INTO @DB_NAME
WHILE @@Fetch_Status = 0
BEGIN
EXEC ('INSERT INTO #TempICITEM ([DbName],[ICITEMId],[Name],[Description]) SELECT ''' + @DB_NAME + ''' DbName,[DbName],[ICITEMId],[Name],[Description] FROM ' + @DB_NAME + '.dbo.ICITEM')
FETCH NEXT FROM CURSOR_ALLDB_NAMES INTO @DB_NAME
END

CLOSE CURSOR_ALLDB_NAMES
DEALLOCATE CURSOR_ALLDB_NAMES

SELECT * From #TempICITEM