如何使用 sql 脚本更改列的属性
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How to alter a column's attribute using sql script
提问by Jerameel Resco
How can I alter a column's attribute using a sql script?
如何使用 sql 脚本更改列的属性？
Here's what I've tried but I got errors:
这是我尝试过但出现错误的方法：
ALTER TABLE [dbo].[tblBiometricPattern] COLUMN BiometricPatternID TINYINT NOT NULL IDENTITY(1,1)
Thank you in advance.
先感谢您。
Here's the error message that appears when executed:
这是执行时出现的错误消息：
Incorrect syntax near the keyword 'COLUMN'.
采纳答案by Damien_The_Unbeliever
If you're trying to alter the column so that it's an IDENTITY column... you can't do that. You can add a new column with the identity property, but you can't alter an existing column.
如果您试图更改该列，使其成为 IDENTITY 列……您不能这样做。您可以添加具有标识属性的新列，但不能更改现有列。
If that's not what you're trying to do, perhaps you could include the actual error messagesyou're getting.
如果这不是您想要做的，也许您可以包含您收到的实际错误消息。
The general form for altering an existing column is:
更改现有列的一般形式是：
ALTER TABLE [dbo].[tblBiometricPattern] ALTER COLUMN BiometricPatternID TINYINT NOT NULL IDENTITY(1,1)
(that is, you were missing the word "ALTER" before COLUMN). But as I say, this will now return an error telling you that you can't change the IDENTITY property of the column.
（也就是说，您在 COLUMN 之前遗漏了“ALTER”一词）。但正如我所说，这现在将返回一个错误，告诉您无法更改列的 IDENTITY 属性。
If the column is alreadyan identity column, and you're just altering the datatype, then leave off the IDENTITY() property. It will still be an identity column:
如果该列已经是一个标识列，而您只是在更改数据类型，则不要使用 IDENTITY() 属性。它仍然是一个标识列：
ALTER TABLE [dbo].[tblBiometricPattern] ALTER COLUMN BiometricPatternID TINYINT NOT NULL
回答by bsanneh
ALTER TABLE table_name ALTER COLUMN column_name datatype
ALTER TABLE table_name ALTER COLUMN column_name 数据类型
回答by Saleh Enam Shohag
If you want to alter/modify column of a table.
For MySQL / Oracle (prior version 10G):
如果要更改/修改表的列。
对于 MySQL/Oracle（10G 之前的版本）：
ALTER TABLE table_name MODIFY COLUMN column_name datatype;
For Oracle 10G and later:
对于 Oracle 10G 及更高版本：
ALTER TABLE table_name MODIFY column_name datatype;
