SET QUOTED_IDENTIFIER (Transact-SQL)
Causes SQL Server to follow the ISO rules regarding quotation mark delimiting identifiers and literal strings. Identifiers delimited by double quotation marks can be either Transact-SQL reserved keywords or can contain characters not generally allowed by the Transact-SQL syntax rules for identifiers.
When SET QUOTED_IDENTIFIER is ON, identifiers can be delimited by double quotation marks, and literals must be delimited by single quotation marks. When SET QUOTED_IDENTIFIER is OFF, identifiers cannot be quoted and must follow all Transact-SQL rules for identifiers. For more information, see Identifiers. Literals can be delimited by either single or double quotation marks.
When SET QUOTED_IDENTIFIER is ON (default), all strings delimited by double quotation marks are interpreted as object identifiers. Therefore, quoted identifiers do not have to follow the Transact-SQL rules for identifiers. They can be reserved keywords and can include characters not generally allowed in Transact-SQL identifiers. Double quotation marks cannot be used to delimit literal string expressions; single quotation marks must be used to enclose literal strings. If a single quotation mark (') is part of the literal string, it can be represented by two single quotation marks ("). SET QUOTED_IDENTIFIER must be ON when reserved keywords are used for object names in the database.
When SET QUOTED_IDENTIFIER is OFF, literal strings in expressions can be delimited by single or double quotation marks. If a literal string is delimited by double quotation marks, the string can contain embedded single quotation marks, such as apostrophes.
SET QUOTED_IDENTIFIER must be ON when you are creating or changing indexes on computed columns or indexed views. If SET QUOTED_IDENTIFIER is OFF, CREATE, UPDATE, INSERT, and DELETE statements on tables with indexes on computed columns or indexed views will fail. For more information about required SET option settings with indexed views and indexes on computed columns, see "Considerations When You Use the SET Statements" in SET Statements (Transact-SQL).
The SQL Server Native Client ODBC driver and SQL Server Native Client OLE DB Provider for SQL Server automatically set QUOTED_IDENTIFIER to ON when connecting. This can be configured in ODBC data sources, in ODBC connection attributes, or OLE DB connection properties. The default for SET QUOTED_IDENTIFIER is OFF for connections from DB-Library applications.
When a table is created, the QUOTED IDENTIFIER option is always stored as ON in the table's metadata even if the option is set to OFF when the table is created.
When a stored procedure is created, the SET QUOTED_IDENTIFIER and SET ANSI_NULLS settings are captured and used for subsequent invocations of that stored procedure.
When executed inside a stored procedure, the setting of SET QUOTED_IDENTIFIER is not changed.
When SET ANSI_DEFAULTS is ON, SET QUOTED_IDENTIFIER is enabled.
SET QUOTED_IDENTIFIER is set at parse time. Setting at parse time means that if the SET statement is present in the batch or stored procedure, it takes effect, regardless of whether code execution actually reaches that point; and the SET statement takes effect before any statements are executed.
Using brackets, [ and ], to delimit identifiers is not affected by the QUOTED_IDENTIFIER setting.
A. Using the quoted identifier setting and reserved word object names
The following example shows that the SET QUOTED_IDENTIFIER setting must be ON, and the keywords in table names must be in double quotation marks to create and use objects that have reserved keyword names.
SET QUOTED_IDENTIFIER OFF GO -- An attempt to create a table with a reserved keyword as a name -- should fail. CREATE TABLE "select" ("identity" INT IDENTITY NOT NULL, "order" INT NOT NULL); GO SET QUOTED_IDENTIFIER ON; GO -- Will succeed. CREATE TABLE "select" ("identity" INT IDENTITY NOT NULL, "order" INT NOT NULL); GO SELECT "identity","order" FROM "select" ORDER BY "order"; GO DROP TABLE "SELECT"; GO SET QUOTED_IDENTIFIER OFF; GO
B. Using the quoted identifier setting with single and double quotation marks
The following example shows the way single and double quotation marks are used in string expressions with SET QUOTED_IDENTIFIER set to ON and OFF.
SET QUOTED_IDENTIFIER OFF; GO USE AdventureWorks2008R2; IF EXISTS(SELECT TABLE_NAME FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_NAME = 'Test') DROP TABLE dbo.Test; GO USE AdventureWorks2008R2; CREATE TABLE dbo.Test (ID INT, String VARCHAR(30)) ; GO -- Literal strings can be in single or double quotation marks. INSERT INTO dbo.Test VALUES (1, "'Text in single quotes'"); INSERT INTO dbo.Test VALUES (2, '''Text in single quotes'''); INSERT INTO dbo.Test VALUES (3, 'Text with 2 '''' single quotes'); INSERT INTO dbo.Test VALUES (4, '"Text in double quotes"'); INSERT INTO dbo.Test VALUES (5, """Text in double quotes"""); INSERT INTO dbo.Test VALUES (6, "Text with 2 """" double quotes"); GO SET QUOTED_IDENTIFIER ON; GO -- Strings inside double quotation marks are now treated -- as object names, so they cannot be used for literals. INSERT INTO dbo."Test" VALUES (7, 'Text with a single '' quote'); GO -- Object identifiers do not have to be in double quotation marks -- if they are not reserved keywords. SELECT ID, String FROM dbo.Test; GO DROP TABLE dbo.Test; GO SET QUOTED_IDENTIFIER OFF; GO
Here is the result set.
1 'Text in single quotes'
2 'Text in single quotes'
3 Text with 2 '' single quotes
4 "Text in double quotes"
5 "Text in double quotes"
6 Text with 2 "" double quotes
7 Text with a single ' quote