blocks|key|1770254|text|如果在列名或标识符中使用关键字或特殊字符，则需要使用方括号。您可以将列命名为[First+Name]+(带空格)-但是每次引用该列时都需要使用方括号。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1770255|较新的工具将它们添加到任何地方，以防万一或保持一致性。|1770256|entityMap^0|12|C|0|0^^$0|@$1|2|3|4|5|6|7|J|8|@$9|K|A|L|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|M|8|@]|D|@]|E|$]]|$1|H|3|-4|5|6|7|N|8|@]|D|@]|E|$]]]|I|$]]

The brackets are required if you use keywords or special chars in the column names or identifiers. You could name a column <code>[First Name]</code> (with a space) – but then you'd need to use brackets every time you referred to that column.
The newer tools add them everywhere just in case or for consistency.

blocks|key|1555232|text|如果您的列与SQL关键字具有相同的名称，或者其中包含空格，则它们很方便。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1555233|示例：|1555234|create+table+test+(+id+int,+user+varchar(20)+)|code-block|syntax|javascript|1555235|哦不！关键字“user”附近的语法不正确。但这一点：|1555236|create+table+test+(+id+int,+[user]+varchar(20)+)|1555237|工作正常。|1555238|entityMap^0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|R|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|S|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|T|8|@]|9|@]|A|$]]|$1|K|3|L|5|F|7|U|8|@]|9|@]|A|$G|H]]|$1|M|3|N|5|6|7|V|8|@]|9|@]|A|$]]|$1|O|3|-4|5|6|7|W|8|@]|9|@]|A|$]]]|P|$]]

They're handy if your columns have the same names as SQL keywords, or have spaces in them.

Example:

<pre><code>create table test ( id int, user varchar(20) )
</code></pre>

Oh no! Incorrect syntax near the keyword 'user'.
But this:

<pre><code>create table test ( id int, [user] varchar(20) )
</code></pre>

Works fine.

blocks|key|1555259|text|例如，如果您(出于某种原因)使用带有某些字符的列名，则它们非常有用。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1555260|Select+First+Name+From+People|code-block|syntax|javascript|1555261|不起作用，但是将列名放在方括号中会起作用。|1555262|Select+[First+Name]+From+People|1555263|简而言之，它是一种显式声明对象名称的方法；列、表、数据库、用户或服务器。|1555264|entityMap^0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|Q|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|R|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|S|8|@]|9|@]|A|$]]|$1|M|3|-4|5|6|7|T|8|@]|9|@]|A|$]]]|N|$]]

They are useful if you are (for some reason) using column names with certain characters for example.

<pre><code>Select First Name From People
</code></pre>

would not work, but putting square brackets around the column name would work

<pre><code>Select [First Name] From People
</code></pre>

In short, it's a way of explicitly declaring a object name; column, table, database, user or server.

blocks|key|1555296|text|不管遵循避免使用保留字的命名约定，Microsoft都会添加新的保留字。使用方括号可以将代码升级到新的SQL+Server版本，而无需首先编辑客户端代码中的Microsoft新保留字。编辑可能是一个重要的问题。这可能会导致您的项目过早退出...|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1555297|当您想要替换脚本中的所有内容时，方括号也很有用。如果批处理包含名为@String的变量和名为String的列，则可以将该列重命名为NewString，而无需将@String重命名为@NewString。|1555298|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|F|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|G|8|@]|9|@]|A|$]]|$1|D|3|-4|5|6|7|H|8|@]|9|@]|A|$]]]|E|$]]

Regardless of following a naming convention that avoids using reserved words, Microsoft does add new reserved words. Using brackets allows your code to be upgraded to a new SQL Server version, without first needing to edit Microsoft's newly reserved words out of your client code. That editing can be a significant concern. It may cause your project to be prematurely retired....

Brackets can also be useful when you want to Replace All in a script. If your batch contains a variable named @String and a column named [String], you can rename the column to [NewString], without renaming @String to @NewString.

blocks|key|1555183|text|列名可以包含字符和保留字，这些字符和保留字会使查询执行引擎感到困惑，因此始终将它们括起来可以防止这种情况发生。我想，比检查问题然后处理它要容易得多。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1555184|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

Column names can contain characters and reserved words that will confuse the query execution engine, so placing brackets around them at all times prevents this from happening. Easier than checking for an issue and then dealing with it, I guess.

blocks|key|1770420|text|在20世纪90年代SQL的黑暗时代，这是一个很好的实践，因为SQL设计人员试图将字典中的每个单词作为关键字添加到字典中，以应对不断涌现的新特性，并将其称为SQL3草案。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1770421|所以它保持了向前兼容性。|1770422|我发现它还有一个很好的副作用，当你在代码审查和重构中使用grep时，它会有很大的帮助。|1770423|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|H|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|I|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|J|8|@]|9|@]|A|$]]|$1|F|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|G|$]]

During the dark ages of SQL in the 1990s it was a good practice as the SQL designers were trying to add each word in the dictionary as keyword for endless avalanche of new features and they called it the SQL3 draft. 

So it keeps forward compatibility. 

And i found that it has another nice side effect, it helps a lot when you use grep in code reviews and refactoring.

blocks|key|1555123|text|当列名是保留字时，可以使用方括号。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1555124|如果以编程方式从不受控制的列名集合生成SQL语句，则可以通过始终使用方括号来避免问题。|1555125|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|F|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|G|8|@]|9|@]|A|$]]|$1|D|3|-4|5|6|7|H|8|@]|9|@]|A|$]]]|E|$]]

The brackets can be used when column names are reserved words.

If you are programatically generating the SQL statement from a collection of column names you don't control, then you can avoid problems by always using the brackets.

blocks|key|1770365|text|此外，一些Sharepoint数据库的名称中包含连字符。在SQL语句中使用方括号可以正确解析名称。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1770366|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

In addition
Some Sharepoint databases contain hyphens in their names. Using square brackets in SQL Statements allow the names to be parsed correctly.

blocks|key|1555201|text|我相信这是为了保持一致性……只有在列名中有空格或特殊字符时才需要它们，但在IDE生成SQL时始终包含它们会更简洁。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1555202|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

I believe it adds them there for consistency... they're only required when you have a space or special character in the column name, but it's cleaner to just include them all the time when the IDE generates SQL.

blocks|key|1555385|text|它们对于标识SQL中的每个元素都很有用。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1555386|例如：|1555387|CREATE+TABLE+SchemaName.TableName+(|code-block|syntax|javascript|1555388|这实际上会在default+dbo模式下创建一个名为SchemaName.TableName的表，即使其目的可能是在SchemaName模式内创建表。|offset|length|style|CODE|1555389|正确的方法如下：|1555390|CREATE+TABLE+[SchemaName].[TableName]+(|1555391|现在它知道了表名是什么，以及应该在哪个模式中创建它(正确地在SchemaName模式中，而不是在默认的dbo模式中)|1555392|entityMap^0|0|0|0|E|3|Q|K|1M|A|0|0|0|U|A|1F|3|0^^$0|@$1|2|3|4|5|6|7|W|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|X|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|Y|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|Z|8|@$K|10|L|11|M|N]|$K|12|L|13|M|N]|$K|14|L|15|M|N]]|9|@]|A|$]]|$1|O|3|P|5|6|7|16|8|@]|9|@]|A|$]]|$1|Q|3|R|5|F|7|17|8|@]|9|@]|A|$G|H]]|$1|S|3|T|5|6|7|18|8|@$K|19|L|1A|M|N]|$K|1B|L|1C|M|N]]|9|@]|A|$]]|$1|U|3|-4|5|6|7|1D|8|@]|9|@]|A|$]]]|V|$]]

They are useful to identify each elements in SQL.
For example:
<pre><code>CREATE TABLE SchemaName.TableName (
</code></pre>
This would actually create a table by the name <code>SchemaName.TableName</code> under default <code>dbo</code> schema even though the intention might be to create the table inside the <code>SchemaName</code> schema.
The correct way would be the following:
<pre><code>CREATE TABLE [SchemaName].[TableName] (
</code></pre>
Now it it knows what is the table name and in which schema should it be created in (rightly in the <code>SchemaName</code> schema and not in the default <code>dbo</code> schema)

I've noticed that Visual Studio 2008 is placing square brackets around column names in sql. Do the brackets offer any advantage? When I hand code T-SQL I've never bothered with them.

Example:

Visual Studio:

<pre><code>SELECT [column1], [column2] etc...
</code></pre>

My own way:

<pre><code>SELECT column1, column2 etc...
</code></pre>

What is the use of the square brackets [] in sql statements?

Visual Studio

SQL Server

数据库

服务器

我注意到Visual Studio2008在sql中用方括号将列名括起来。支架有什么优势吗？当我手工编写T-SQL代码时，我从来没有为它们操心过。示例：Visual Studio：SELECT [column1], [column2] etc...我自己的方式：SELECT column1, column2 etc...

问方括号[]在sql语句中的用途是什么？
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