如何通过脚本自动生成临时表列和数据类型

Question

我经常在 SQL 中创建临时表，我正在寻找一种为表定义自动生成列名和数据类型的方法，这样我就不必每次都查看它们。

例如我运行：

SELECT CustomerID
  ClientID,
  FirstName
  LastName
INTO #Test
From dbo.Customer

首先使用我需要的适当列和数据设置临时表。一旦我完成了这一切，我就返回并取出 INTO 语句并写下以下内容：

CREATE TABLE #Test
(
...
...
);

我想找到一种从临时表的初始创建中自动生成列名和数据类型的方法。现在，由于我最初是插入到一个自动创建的临时表中，所以我使用这个：

EXEC tempdb..sp_help '#Test';

这为我提供了我需要的一切，而无需查看所有列数据类型，但我想知道是否有一种方法可以自动生成类似这样的列名。所以自动生成会生成：

CustomerID int,
ClientID int,
FirstName varchar(50),
LastName varchar(50)

这将允许我将其复制并粘贴到我的创建表语句中。

Answer 1

这可能会给你一个开始：

DECLARE @viewname VARCHAR(50);
SET @viewname ='tableorviewname';
SELECT  c.name + ' '+ t.name + 
case t.name  
WHEN 'varchar' THEN '('+CAST(c.max_length AS VARCHAR(3) )+'),'
ELSE ',' 
end
FROM sys.columns c
INNER JOIN sys.types AS t ON c.system_type_id = t.system_type_id
WHERE object_id = (SELECT object_id from sys.objects where name = @viewname)
ORDER BY c.column_id

编辑：临时表：

临时表略有不同，例如，这在 sql 2008 中适用于名为 #tv_source 的临时表

DECLARE @viewortablename VARCHAR(50);
SET @viewortablename ='tempdb..#tv_source';
SELECT  c.name + ' '+ t.name + 
case t.name  
WHEN 'varchar' THEN '('+CAST(c.max_length AS VARCHAR(3) )+'),'
ELSE ',' 
end
FROM tempdb.sys.columns c
INNER JOIN sys.types AS t ON c.system_type_id = t.system_type_id
WHERE object_id =  object_id(@viewortablename)
ORDER BY c.column_id

注意：这给出了一个逗号分隔的列表，但没有尝试删除最后一个逗号，它只给出一个列表，您可能希望将其放在字符串上并进行操作等，然后用作动态 sql 或东西。不过，它应该让您开始做自己想做的事。

对其他人的注意，sql 2000 不会正确显示长度，例如在 varchar(45) 上，它只会列出 varchar 部分，我没有尝试针对这个问题重新处理。

Answer 2

SELECT
', ['+ac.name+'] '+Type_Name(User_type_id)+
CASE WHEN Type_Name(User_type_id) = 'Decimal' 
      THEN +'('+CONVERT(Varchar(4),ac.Precision)+','+CONVERT(Varchar(4),ac.Scale)+')' 
      WHEN Type_Name(User_type_id) IN 
            ('tinyint','smallint','int','real','money','float','numeric','smallmoney','DateTime') 
      THEN ''
      ELSE +'('+CONVERT(Varchar(4),ac.Max_Length)+')' 
END AS TableColumn
FROM Tempdb.sys.all_columns AS ac
      INNER JOIN Tempdb.Sys.SysObjects AS so
            ON so.ID = ac.Object_ID
WHERE 1 = 1
AND so.Name = '##YourTempTableGoesHere'

Answer 3

...我已经创建了一个函数，可以输出列和数据类型的列表，如果对象是表，那对你有用吗？

CREATE FUNCTION [dbo].[fnDiscoverColumns]
( @PObjectName NVARCHAR(300) )

RETURNS @Data TABLE ( ColumnList NVARCHAR(350) )

AS
BEGIN

DECLARE @PObjectID TABLE  ( [object_id] INT )
INSERT @PObjectID ( [object_id] )

SELECT [object_id] FROM sys.objects AS O WHERE O.name = @PObjectName AND O.type = 'U'

DECLARE @PObjectDetails TABLE ( [RowNo] INT,[ColumnName] NVARCHAR(300),[XType] INT,[DataType] NVARCHAR(100),[system_type_id] INT,[user_type_id] INT,[MaxLength] NVARCHAR(5),[Precision] INT,[Scale] INT,[ColumnList] NVARCHAR(300) )

INSERT @PObjectDetails ( [RowNo],[ColumnName],[XType],[DataType],[system_type_id],[user_type_id],[MaxLength],[Precision],[Scale],[ColumnList] )

SELECT DISTINCT
ROW_NUMBER() OVER (ORDER BY (SELECT NULL)) AS 'RowNo',
C.name AS 'ColumnName',
T.xtype AS 'XType',
UPPER(T.name) AS 'DataType',
C.system_type_id,
C.user_type_id,
CASE WHEN C.max_length < 0 THEN 'MAX' ELSE CAST(C.max_length AS VARCHAR) END AS 'MaxLength',
C.precision AS 'Precision',
C.scale AS 'Scale',
CASE
WHEN [XType] IN (34,35,36,40,48,52,56,58,59,60,61,62,98,99,104,122,127,189,240,241) THEN QUOTENAME(C.name) +'  '+ UPPER(T.name) +',' 
WHEN [XType] IN (106,108) THEN QUOTENAME(C.name) +'  '+ UPPER(T.name) +'('+ CAST([Precision] AS VARCHAR) +','+ CAST(C.scale AS VARCHAR) +'),'
WHEN [XType] IN (41,42,43,165,167,173,175,231,239) THEN QUOTENAME(C.name) +'  '+ UPPER(T.name) +'('+ CASE WHEN C.max_length < 0 THEN 'MAX'  WHEN C.max_length > 1 THEN CAST(C.max_length / 2 AS VARCHAR) ELSE CAST(C.max_length AS VARCHAR) END +'),' ELSE NULL END AS 'ColumnList'
FROM sys.all_columns AS C
JOIN systypes AS T ON C.system_type_id = T.xusertype
WHERE C.object_id = (SELECT * FROM @PObjectID)  --373576369

--Return column names and data types
INSERT @Data
SELECT 'CREATE TABLE #ColumnsList ('

INSERT @Data
SELECT 
CASE WHEN C.RowNo = (SELECT MAX(RowNo) FROM @PObjectDetails) THEN LEFT(C.ColumnList, ABS(LEN(C.ColumnList + ',') - 2)) ELSE C.ColumnList END AS 'GeneratedColumns'     
FROM @PObjectDetails AS C

INSERT @Data
SELECT ')'

RETURN
END
GO

一旦提交到数据库，像这样运行它：

SELECT * FROM [dbo].[fnDiscoverColumns] ('ExecutionLogStorage') --name of table

这应该会给你这样的输出：

CREATE TABLE #ColumnsList (
[LogEntryId]  BIGINT,
[InstanceName]  NVARCHAR(38),
[ReportID]  UNIQUEIDENTIFIER,
[UserName]  NVARCHAR(260),
[ExecutionId]  NVARCHAR(64),
[RequestType]  TINYINT,
[Format]  NVARCHAR(26),
[Parameters]  NTEXT,
[ReportAction]  TINYINT,
[TimeStart]  DATETIME,
[TimeEnd]  DATETIME,
[TimeDataRetrieval]  INT,
[TimeProcessing]  INT,
[TimeRendering]  INT,
[Source]  TINYINT,
[Status]  NVARCHAR(40),
[ByteCount]  BIGINT,
[RowCount]  BIGINT,
[AdditionalInfo]  XML
)