What is the use of the square brackets in sql statements

Question

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   SELECT  column1    column2  etc      My own way   SELECT column1  column2 etc

User · Answer

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

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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

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They are useful if you are  for some reason  using column names with certain characters for example   Select First Name From People   would not work  but putting square brackets around the column name would work  Select  First Name  From People   In short  it s a way of explicitly declaring a object name  column  table  database  user or server

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

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The brackets are required if you use keywords or special chars in the column names or identifiers  You could name a column  First Name   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

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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

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

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They re handy if your columns have the same names as SQL keywords  or have spaces in them   Example   create table test   id int  user varchar 20      Oh no  Incorrect syntax near the keyword  user   But this   create table test   id int   user  varchar 20      Works fine

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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

User · Answer

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

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

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