Question

我需要ALTER表格中几列的数据类型。

对于单个列，以下工作正常：

ALTER TABLE tblcommodityOHLC
ALTER COLUMN
    CC_CommodityContractID NUMERIC(18,0)

但是如何在一个语句中更改多个列？以下不起作用：

ALTER TABLE tblcommodityOHLC
ALTER COLUMN
    CC_CommodityContractID NUMERIC(18,0), 
    CM_CommodityID NUMERIC(18,0)

Answer 1

这是不可能的。您需要逐个完成此操作。

您可以使用修改后的列创建临时表，复制数据，删除原始表并将临时表重命名为原始名称。

Answer 2

在单个ALTER TABLE语句中执行多个ALTER COLUMN操作不是可能的。

请参阅此处的ALTER TABLE语法：
http://msdn.microsoft.com/en-US/library/ms190273.aspx

您可以执行多个ADD或多个DROP COLUMN，但只能执行一个ALTER 列中。

Answer 3

以下解决方案不是用于更改多列的单个语句，但是，它使生活变得简单：

生成表格的CREATE脚本。
将第一行CREATE TABLE替换为ALTER TABLE [TableName] ALTER COLUMN
从列表中删除不需要的列。
根据需要更改列数据类型。
执行查找和替换... ，如下所示：
1. 查找：NULL，
2. 替换为：NULL; ALTER TABLE [TableName] ALTER COLUMN
3. 点击替换按钮。
运行脚本。

希望它能节省很多时间：））

Answer 4

正如其他人已经回答的那样，您需要多个ALTER TABLE语句。尝试：

ALTER TABLE tblcommodityOHLC alter column CC_CommodityContractID NUMERIC(18,0);
ALTER TABLE tblcommodityOHLC alter column CM_CommodityID NUMERIC(18,0);

等

Answer 5

正如许多其他人所说，您需要使用多个ALTER COLUMN语句，每个语句对应要修改的每个列。

如果要将表中的所有或多个列修改为相同的数据类型（例如将VARCHAR字段从50个字符扩展到100个字符），可以使用下面的查询自动生成所有语句。如果要在多个字段中替换相同的字符（例如从所有列中删除\ t），此技术也很有用。

SELECT
     TABLE_CATALOG
    ,TABLE_SCHEMA
    ,TABLE_NAME
    ,COLUMN_NAME
    ,'ALTER TABLE ['+TABLE_SCHEMA+'].['+TABLE_NAME+'] ALTER COLUMN ['+COLUMN_NAME+'] VARCHAR(300)' as 'code'
FROM INFORMATION_SCHEMA.COLUMNS
WHERE TABLE_NAME = 'your_table' AND TABLE_SCHEMA = 'your_schema'

这为您生成每列的ALTER TABLE语句。

Answer 6

如果您在management studio中执行更改并生成脚本，则会生成一个新表，并将旧数据插入到具有已更改数据类型的数据中。这是一个改变两列数据类型的小例子

/*
   12 August 201008:30:39
   User: 
   Server: CLPPRGRTEL01\TELSQLEXPRESS
   Database: Tracker_3
   Application: 
*/

/* To prevent any potential data loss issues, you should review this script in detail before running it outside the context of the database designer.*/
BEGIN TRANSACTION
SET QUOTED_IDENTIFIER ON
SET ARITHABORT ON
SET NUMERIC_ROUNDABORT OFF
SET CONCAT_NULL_YIELDS_NULL ON
SET ANSI_NULLS ON
SET ANSI_PADDING ON
SET ANSI_WARNINGS ON
COMMIT
BEGIN TRANSACTION
GO
ALTER TABLE dbo.tblDiary
    DROP CONSTRAINT FK_tblDiary_tblDiary_events
GO
ALTER TABLE dbo.tblDiary_events SET (LOCK_ESCALATION = TABLE)
GO
COMMIT
BEGIN TRANSACTION
GO
CREATE TABLE dbo.Tmp_tblDiary
    (
    Diary_ID int NOT NULL IDENTITY (1, 1),
    Date date NOT NULL,
    Diary_event_type_ID int NOT NULL,
    Notes varchar(MAX) NULL,
    Expected_call_volumes real NULL,
    Expected_duration real NULL,
    Skill_affected smallint NULL
    )  ON T3_Data_2
     TEXTIMAGE_ON T3_Data_2
GO
ALTER TABLE dbo.Tmp_tblDiary SET (LOCK_ESCALATION = TABLE)
GO
SET IDENTITY_INSERT dbo.Tmp_tblDiary ON
GO
IF EXISTS(SELECT * FROM dbo.tblDiary)
     EXEC('INSERT INTO dbo.Tmp_tblDiary (Diary_ID, Date, Diary_event_type_ID, Notes, Expected_call_volumes, Expected_duration, Skill_affected)
        SELECT Diary_ID, Date, Diary_event_type_ID, CONVERT(varchar(MAX), Notes), Expected_call_volumes, Expected_duration, CONVERT(smallint, Skill_affected) FROM dbo.tblDiary WITH (HOLDLOCK TABLOCKX)')
GO
SET IDENTITY_INSERT dbo.Tmp_tblDiary OFF
GO
DROP TABLE dbo.tblDiary
GO
EXECUTE sp_rename N'dbo.Tmp_tblDiary', N'tblDiary', 'OBJECT' 
GO
ALTER TABLE dbo.tblDiary ADD CONSTRAINT
    PK_tblDiary PRIMARY KEY NONCLUSTERED 
    (
    Diary_ID
    ) WITH( PAD_INDEX = OFF, FILLFACTOR = 86, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON T3_Data_2

GO
CREATE UNIQUE CLUSTERED INDEX tblDiary_ID ON dbo.tblDiary
    (
    Diary_ID
    ) WITH( PAD_INDEX = OFF, FILLFACTOR = 86, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON T3_Data_2
GO
CREATE NONCLUSTERED INDEX tblDiary_date ON dbo.tblDiary
    (
    Date
    ) WITH( PAD_INDEX = OFF, FILLFACTOR = 86, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON T3_Data_2
GO
ALTER TABLE dbo.tblDiary WITH NOCHECK ADD CONSTRAINT
    FK_tblDiary_tblDiary_events FOREIGN KEY
    (
    Diary_event_type_ID
    ) REFERENCES dbo.tblDiary_events
    (
    Diary_event_ID
    ) ON UPDATE  CASCADE 
     ON DELETE  CASCADE 

GO
COMMIT

Answer 7

select 'ALTER TABLE ' + OBJECT_NAME(o.object_id) + 
    ' ALTER COLUMN ' + c.name + ' DATETIME2 ' + 
    CASE WHEN c.is_nullable = 0 THEN 'NOT NULL' ELSE 'NULL' END
from sys.objects o
inner join sys.columns c on o.object_id = c.object_id
inner join sys.types t on c.system_type_id = t.system_type_id
where o.type='U'
and c.name = 'Timestamp'
and t.name = 'datetime'
order by OBJECT_NAME(o.object_id)

由devio提供

Answer 8

感谢Evan的代码示例，我能够对其进行更多修改，并使其更具针对以特定列名开头的表，并处理约束的细节。我运行了该代码，然后复制了[CODE]列并毫无问题地执行了它。

USE [Table_Name]
GO
SELECT
     TABLE_CATALOG
    ,TABLE_SCHEMA
    ,TABLE_NAME
    ,COLUMN_NAME
    ,DATA_TYPE
    ,'ALTER TABLE ['+TABLE_SCHEMA+'].['+TABLE_NAME+'] DROP CONSTRAINT [DEFAULT_'+TABLE_NAME+'_'+COLUMN_NAME+']; 
ALTER TABLE  ['+TABLE_SCHEMA+'].['+TABLE_NAME+'] ALTER COLUMN ['+COLUMN_NAME+'] datetime2 (7) NOT NULL 
ALTER TABLE  ['+TABLE_SCHEMA+'].['+TABLE_NAME+'] ADD CONSTRAINT [DEFAULT_'+TABLE_NAME+'_'+COLUMN_NAME+'] DEFAULT (''3/6/2018 6:47:23 PM'') FOR ['+COLUMN_NAME+']; 
GO' AS '[CODE]'
FROM INFORMATION_SCHEMA.COLUMNS
WHERE TABLE_NAME LIKE 'form_%' AND TABLE_SCHEMA = 'dbo'
 AND (COLUMN_NAME = 'FormInserted' OR COLUMN_NAME = 'FormUpdated')
 AND DATA_TYPE = 'datetime'

Answer 9

如果您不想自己编写整个内容并将所有列更改为相同的数据类型，则可以更轻松：

select 'alter table tblcommodityOHLC alter column '+name+ 'NUMERIC(18,0);'
from syscolumns where id = object_id('tblcommodityOHLC ')

您可以将输出复制并粘贴为查询

Answer 10

我们可以在单个查询中更改多个列，如下所示：

ALTER TABLE `tblcommodityOHLC`
    CHANGE COLUMN `updated_on` `updated_on` DATETIME NULL DEFAULT NULL AFTER `updated_by`,
    CHANGE COLUMN `delivery_datetime` `delivery_datetime` DATETIME NULL DEFAULT CURRENT_TIMESTAMP AFTER `delivery_status`;

只需以逗号分隔查询。

Answer 11

-- create temp table 
CREATE TABLE temp_table_alter
(
column_name varchar(255)    
);

-- insert those coulmns in temp table for which we nee to alter size of columns 
INSERT INTO temp_table_alter (column_name) VALUES ('colm1');
INSERT INTO temp_table_alter (column_name) VALUES ('colm2');
INSERT INTO temp_table_alter (column_name) VALUES ('colm3');
INSERT INTO temp_table_alter (column_name) VALUES ('colm4');

DECLARE @col_name_var varchar(255);
DECLARE alter_table_cursor CURSOR FOR
select column_name from temp_table_alter ;

OPEN alter_table_cursor
FETCH NEXT FROM alter_table_cursor INTO @col_name_var
WHILE @@FETCH_STATUS = 0
 BEGIN

 PRINT('ALTER COLUMN ' + @col_name_var);
 EXEC ('ALTER TABLE Original-table  ALTER COLUMN ['+ @col_name_var + '] DECIMAL(11,2);')

 FETCH NEXT FROM alter_table_cursor INTO @col_name_var
 END

CLOSE alter_table_cursor
DEALLOCATE alter_table_cursor

-- at the end drop temp table
drop table temp_table_alter;

Answer 12

如果我正确理解了您的问题，您可以使用下面提到的查询在表格中添加多个列。

查询：

Alter table tablename add (column1 dataype, column2 datatype);

Answer 13

将ALTER COLUMN语句放在括号内，它应该可以正常工作。

ALTER TABLE tblcommodityOHLC alter ( column  
CC_CommodityContractID NUMERIC(18,0), 
CM_CommodityID NUMERIC(18,0) )

如何在SQL Server中一次更改多个列

13 个答案: