T-SQL style guide

Overview

Intended as a guide towards clean, concise T-SQL coding standards that are as version-independent as possible.

Original SQL style guide by Simon Holywell is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License. Based on a work at http://www.sqlstyle.guide.

General

Do

Use consistent and descriptive identifiers and names.
Wrap object names in square brackets.
Use two-part names for isolated databases and three-part names when outside databases are being utilized.
Make judicious use of white space and indentation to make code easier to read.
Store ISO-8601 compliant time and date information (YYYY-MM-DD HH:MM:SS.SSSSS) with DATE, TIME, DATETIME2, and DATETIMEOFFSET.
Try to use standard SQL functions instead of Microsoft specific functions for reasons of portability when functionality is the same.
Keep code succinct and devoid of redundant SQL—such as unnecessary quoting or parentheses or WHERE clauses that can otherwise be derived.
Include comments in SQL code where necessary. Use the C style opening /* and closing */ where possible otherwise precede comments with -- and finish them with a new line.
End each statement with a semicolon.
Use control-of-flow language when advanced scripting or programmability is used.
Supply TRY...CATCH keywords for operationalized DML statements.

SELECT [file_hash]  -- stored ssdeep hash
  FROM [dbo].[file_system]
 WHERE [file_name] = '.vimrc';

/* Updating the file record after writing to the file */
UPDATE [file_system]
   SET [file_modified_date] = '1980-02-22 13:19:01.00000',
       [file_size] = 209732
 WHERE [dbo].[file_name] = '.vimrc';

Avoid

CamelCase—it is difficult to scan quickly.
Plurals—use the more natural collective term where possible instead. For example staff instead of employees or people instead of individuals.
Quoted identifiers—if you must use them then stick to SQL92 double quotes for portability (you may need to configure your SQL server to support this depending on vendor).
Object oriented design principles should not be applied to SQL or database structures.
Using RAISERROR on versions 2012 or greater—THROW is more flexible and succinct.
Commenting out old code or large statements that are not in use. Commenting <> source control.

Naming conventions

General

Ensure the name is unique and does not exist as a reserved keyword.
Keep the length to a maximum of 30 bytes—in practice this is 30 characters unless you are using multi-byte character set.
Names must begin with a letter and may not end with an underscore.
Only use letters, numbers and underscores in names.
Avoid the use of multiple consecutive underscores—these can be hard to read.
Use underscores where you would naturally include a space in the name (first name becomes first_name).
Avoid abbreviations and if you have to use them make sure they are commonly understood.
Use underscores to separate words.

SELECT [first_name]
  FROM [dbo].[staff];

Tables

Use a collective name or, less ideally, a singular form. For example (in order of preference) staff and employee.
Do not prefix with tbl or any other such descriptive prefix or Hungarian notation.
Never give a table the same name as one of its columns and vice versa.
Avoid, where possible, concatenating two table names together to create the name of a relationship table. Rather than cars_mechanics prefer services.
Avoid using underscores in names, unless to designate a suffix to differentiate two versions of a table, such as staff and staff_backup20170101.

Columns

Always use the singular name.
Where possible avoid simply using id as the primary identifier for the table.
Do not add a column with the same name as its table and vice versa.
Always use lowercase except where it may make sense not to such as proper nouns.

Aliasing or correlations

Should relate in some way to the object or expression they are aliasing.
As a rule of thumb the correlation name should be the first letter of each word in the object’s name.
If there is already a correlation with the same name then append a number.
Always include use an explicit alias keyword to make it easier to read. For example (in order of preference) [dbo].[employee] AS [emp] and [emp] = [dbo].[employee]. The former is ANSI compliant, the latter is only specific to T-SQL.
For computed data (SUM() or AVG()) use the name you would give it were it a column defined in the schema.

SELECT [first_name] AS [fn]
  FROM [staff] AS [s1]
  JOIN [dbo].[students] AS [s2]
    ON [s2].[mentor_id] = [s1].[staff_num];

SELECT SUM([s].[monitor_tally]) AS [monitor_total]
  FROM [staff] AS [s];

Stored procedures

The name must contain a verb.
Prefix with usp_ and not sp_ which may conflict with system stored procedures.

Uniform suffixes

The following suffixes have a universal meaning ensuring the columns can be read and understood easily from SQL code. Use the correct suffix where appropriate.

_id—a unique identifier such as a column that is a primary key.
_status—flag value or some other status of any type such as publication_status.
_total—the total or sum of a collection of values.
_num—denotes the field contains any kind of number.
_name—signifies a name such as first_name.
_seq—contains a contiguous sequence of values.
_date—denotes a column that contains the date of something.
_tally—a count.
_size—the size of something such as a file size or clothing.
_addr—an address for the record could be physical or intangible such as ip_addr.

Query syntax

Reserved words

Always use uppercase for the reserved keywords like SELECT and WHERE.

It is best to avoid the abbreviated keywords and use the full length ones where available (prefer ABSOLUTE to ABS).

Do not use database server specific keywords where an ANSI SQL keyword already exists performing the same function. This helps to make code more portable.

SELECT [model_num]
  FROM [dbo].[phones] AS p
 WHERE [p].[release_date] > '2014-09-30';

White space

To make the code easier to read it is important that the correct compliment of spacing is used. Do not crowd code or remove natural language spaces.

Spaces

Spaces should be used to line up the code so that the root keywords all end on the same character boundary. This forms a river down the middle making it easy for the readers eye to scan over the code and separate the keywords from the implementation detail. Rivers are bad in typography, but helpful here.

SELECT [f].[average_height], [f].[average_diameter]
  FROM [flora] AS f
 WHERE [f].[species_name] = 'Banksia'
    OR [f].[species_name] = 'Sheoak'
    OR [f].[species_name] = 'Wattle';

Notice that SELECT, FROM, etc. are all right aligned while the actual column names and implementation specific details are left aligned.

Although not exhaustive always include spaces:

before and after equals (=)
after commas (,)
surrounding apostrophes (') where not within parentheses or with a trailing comma or semicolon.

SELECT [a].[title], [a].[release_date], [a].[recording_date]
  FROM [albums] AS [a]
 WHERE [a].[title] = 'Charcoal Lane'
    OR [a].[title] = 'The New Danger';

Line spacing

Always include newlines/vertical space:

before AND or OR
after semicolons to separate queries for easier reading
after each keyword definition
after a comma when separating multiple columns into logical groups
to separate code into related sections, which helps to ease the readability of large chunks of code.

Keeping all the keywords aligned to the right-hand side and the values left aligned creates a uniform gap down the middle of query. It makes it much easier to scan the query definition over quickly too.

INSERT INTO [dbo].[albums] ([title], [release_date], [recording_date])
VALUES ('Charcoal Lane', '1990-01-01 01:01:01.00000', '1990-01-01 01:01:01.00000'),
       ('The New Danger', '2008-01-01 01:01:01.00000', '1990-01-01 01:01:01.00000');

UPDATE [dbo].[albums]
   SET [release_date] = '1990-01-01 01:01:01.00000'
 WHERE [title] = 'The New Danger';

SELECT [a].[title],
       [a].[release_date], [a].[recording_date], [a].[production_date] -- grouped dates together
  FROM [albums] AS [a]
 WHERE [a].[title] = 'Charcoal Lane'
    OR [a].[title] = 'The New Danger';

Indentation

To ensure that SQL is readable it is important that standards of indentation are followed.

Joins

Joins should be indented to the other side of the river and grouped with a new line where necessary.

SELECT [r].[last_name]
  FROM [riders] AS [r]
       INNER JOIN [bikes] AS [b]
       ON [r].[bike_vin_num] = [b].[vin_num]
          AND [b].[engines] > 2

       INNER JOIN [crew] AS [c]
       ON [r].[crew_chief_last_name] = [c].[last_name]
          AND [c].[chief] = 'Y';

Subqueries

Subqueries should also be aligned to the right side of the river and then laid out using the same style as any other query. Sometimes it will make sense to have the closing parenthesis on a new line at the same character position as it’s opening partner—this is especially true where you have nested subqueries.

SELECT [r].[last_name],
       (SELECT MAX(YEAR([championship_date]))
          FROM [champions] AS [c]
         WHERE [c].[last_name] = [r].[last_name]
           AND [c].[confirmed] = 'Y') AS [last_championship_year]
  FROM [riders] AS [r]
 WHERE [r].[last_name] IN
       (SELECT [c].[last_name]
          FROM [champions] AS [c]
         WHERE YEAR([championship_date]) > '2008'
           AND [c].[confirmed] = 'Y');

Preferred formalisms

Use >= AND < instead of BETWEEN for date ranges.
Similarly use IN() instead of multiple OR clauses.
Avoid pretty-printing data for the UI within queries. Where a value needs to be interpreted before leaving the database use the CASE expression. CASE statements can be nested to form more complex logical structures.
Avoid the use of UNION clauses and temporary tables where possible. If the schema can be optimized to remove the reliance on these features then it most likely should be.
Wrap stored procedure contents in BEGIN...END statements.
Use INNER JOIN instead of JOIN to more clearly match LEFT JOIN syntax.

SELECT CASE [postcode]
       WHEN 'BN1' THEN 'Brighton'
       WHEN 'EH1' THEN 'Edinburgh'
       END AS [city]
  FROM [office_locations]
 WHERE [country] = 'United Kingdom'
   AND [opening_time] BETWEEN 8 AND 9
   AND [postcode] IN ('EH1', 'BN1', 'NN1', 'KW1');

Create syntax

When declaring schema information it is also important to maintain human readable code. To facilitate this ensure the column definitions are ordered and grouped where it makes sense to do so.

Indent column definitions by four (4) spaces within the CREATE definition.

Choosing data types

Where possible do not use vendor specific data types—these are not portable and may not be available in older versions of the same vendor’s software.
Only use REAL or FLOAT types where it is strictly necessary for floating point mathematics otherwise prefer NUMERIC and DECIMAL at all times. Floating point rounding errors are a nuisance!
Do not use deprecated data types NTEXT, TEXT, and IMAGE. Use their equivalents (NVARCHAR(MAX), VARCHAR(MAX), and VARBINARY(MAX)) instead.
Explicitly define the (smallest possible) precision of a column for applicable data types.

Specifying default values

The default value must be the same type as the column—if a column is declared a DECIMAL do not provide an INTEGER default value.
Default values must follow the data type declaration and come before any NOT NULL statement.

Constraints and keys

Constraints and their subset, keys, are a very important component of any database definition. They can quickly become very difficult to read and reason about though so it is important that a standard set of guidelines are followed.

Choosing keys

Deciding the column(s) that will form the keys in the definition should be a carefully considered activity as it will effect performance and data integrity.

The key should be unique to some degree.
Consistency in terms of data type for the value across the schema and a lower likelihood of this changing in the future.
Can the value be validated against a standard format (such as one published by ISO)? Encouraging conformity to point 2.
Keeping the key as simple as possible whilst not being scared to use compound keys where necessary.

It is a reasoned and considered balancing act to be performed at the definition of a database. Should requirements evolve in the future it is possible to make changes to the definitions to keep them up to date.

Defining constraints

Once the keys are decided it is possible to define them in the system using constraints along with field value validation.

General

Tables must have at least one key to be complete and useful.
Constraints should be given a custom name excepting UNIQUE, PRIMARY KEY and FOREIGN KEY where the database vendor will generally supply sufficiently intelligible names automatically.

Layout and order

Specify the primary key first right after the CREATE TABLE statement.
Constraints should be defined directly beneath the column they correspond to. Indent the constraint so that it aligns to the right of the column name.
If it is a multi-column constraint then consider putting it as close to both column definitions as possible and where this is difficult as a last resort include them at the end of the CREATE TABLE definition.
If it is a table level constraint that applies to the entire table then it should also appear at the end.
Use alphabetical order where ON DELETE comes before ON UPDATE.
If it make senses to do so align each aspect of the query on the same character position. For example all NOT NULL definitions could start at the same character position. This is not hard and fast, but it certainly makes the code much easier to scan and read.

Validation

Use LIKE constraints to ensure the integrity of strings where the format is known.
Where the ultimate range of a numerical value is known it must be written as a range CHECK() to prevent incorrect values entering the database or the silent truncation of data too large to fit the column definition. In the least it should check that the value is greater than zero in most cases.
Start and End date values should always have a constraint to ensure the End is after the Start.
CHECK() constraints should be kept in separate clauses to ease debugging.

Example

CREATE TABLE [dbo].[staff] (
    PRIMARY KEY ([staff_num]),
    [staff_num]      INT(5)       NOT NULL,
    [first_name]     VARCHAR(100) NOT NULL,
    [pens_in_drawer] INT(2)       NOT NULL,
                   CONSTRAINT [pens_in_drawer_range]
                   CHECK([pens_in_drawer] >= 1 AND [pens_in_drawer] < 100)
);

Designs to avoid

Object oriented design principles do not effectively translate to relational database designs—avoid this pitfall.
Placing the value in one column and the units in another column. The column should make the units self evident to prevent the requirement to combine columns again later in the application. Use CHECK() to ensure valid data is inserted into the column.
EAV (Entity Attribute Value) tables—use a specialist product intended for handling such schema-less data instead.
Splitting up data that should be in one table across many because of arbitrary concerns such as time-based archiving or location in a multi-national organisation. Later queries must then work across multiple tables with UNION rather than just simply querying one table.

Appendix

Reserved keyword reference

A list of ANSI SQL (92, 99 and 2003) reserved keywords and T-SQL reserved keywords as of SQL Server 2008.

A
ABORT
ABS
ABSOLUTE
ACCESS
ACTION
ADA
ADD
ADMIN
AFTER
AGGREGATE
ALIAS
ALL
ALLOCATE
ALSO
ALTER
ALWAYS
ANALYSE
ANALYZE
AND
ANY
ARE
ARRAY
AS
ASC
ASENSITIVE
ASSERTION
ASSIGNMENT
ASYMMETRIC
AT
ATOMIC
ATTRIBUTE
ATTRIBUTES
AUDIT
AUTHORIZATION
AUTO_INCREMENT
AVG
AVG_ROW_LENGTH
BACKUP
BACKWARD
BEFORE
BEGIN
BERNOULLI
BETWEEN
BIGINT
BINARY
BIT
BIT_LENGTH
BITVAR
BLOB
BOOL
BOOLEAN
BOTH
BREADTH
BREAK
BROWSE
BULK
BY
C
CACHE
CALL
CALLED
CARDINALITY
CASCADE
CASCADED
CASE
CAST
CATALOG
CATALOG_NAME
CEIL
CEILING
CHAIN
CHANGE
CHAR
CHAR_LENGTH
CHARACTER
CHARACTER_LENGTH
CHARACTER_SET_CATALOG
CHARACTER_SET_NAME
CHARACTER_SET_SCHEMA
CHARACTERISTICS
CHARACTERS
CHECK
CHECKED
CHECKPOINT
CHECKSUM
CLASS
CLASS_ORIGIN
CLOB
CLOSE
CLUSTER
CLUSTERED
COALESCE
COBOL
COLLATE
COLLATION
COLLATION_CATALOG
COLLATION_NAME
COLLATION_SCHEMA
COLLECT
COLUMN
COLUMN_NAME
COLUMNS
COMMAND_FUNCTION
COMMAND_FUNCTION_CODE
COMMENT
COMMIT
COMMITTED
COMPLETION
COMPRESS
COMPUTE
CONDITION
CONDITION_NUMBER
CONNECT
CONNECTION
CONNECTION_NAME
CONSTRAINT
CONSTRAINT_CATALOG
CONSTRAINT_NAME
CONSTRAINT_SCHEMA
CONSTRAINTS
CONSTRUCTOR
CONTAINS
CONTAINSTABLE
CONTINUE
CONVERSION
CONVERT
COPY
CORR
CORRESPONDING
COUNT
COVAR_POP
COVAR_SAMP
CREATE
CREATEDB
CREATEROLE
CREATEUSER
CROSS
CSV
CUBE
CUME_DIST
CURRENT
CURRENT_DATE
CURRENT_DEFAULT_TRANSFORM_GROUP
CURRENT_PATH
CURRENT_ROLE
CURRENT_TIME
CURRENT_TIMESTAMP
CURRENT_TRANSFORM_GROUP_FOR_TYPE
CURRENT_USER
CURSOR
CURSOR_NAME
CYCLE
DATA
DATABASE
DATABASES
DATE
DATETIME
DATETIME_INTERVAL_CODE
DATETIME_INTERVAL_PRECISION
DAY
DAY_HOUR
DAY_MICROSECOND
DAY_MINUTE
DAY_SECOND
DAYOFMONTH
DAYOFWEEK
DAYOFYEAR
DBCC
DEALLOCATE
DEC
DECIMAL
DECLARE
DEFAULT
DEFAULTS
DEFERRABLE
DEFERRED
DEFINED
DEFINER
DEGREE
DELAY_KEY_WRITE
DELAYED
DELETE
DELIMITER
DELIMITERS
DENSE_RANK
DENY
DEPTH
DEREF
DERIVED
DESC
DESCRIBE
DESCRIPTOR
DESTROY
DESTRUCTOR
DETERMINISTIC
DIAGNOSTICS
DICTIONARY
DISABLE
DISCONNECT
DISK
DISPATCH
DISTINCT
DISTINCTROW
DISTRIBUTED
DIV
DO
DOMAIN
DOUBLE
DROP
DUAL
DUMMY
DUMP
DYNAMIC
DYNAMIC_FUNCTION
DYNAMIC_FUNCTION_CODE
EACH
ELEMENT
ELSE
ELSEIF
ENABLE
ENCLOSED
ENCODING
ENCRYPTED
END
END-EXEC
ENUM
EQUALS
ERRLVL
ESCAPE
ESCAPED
EVERY
EXCEPT
EXCEPTION
EXCLUDE
EXCLUDING
EXCLUSIVE
EXEC
EXECUTE
EXISTING
EXISTS
EXIT
EXP
EXPLAIN
EXTERNAL
EXTRACT
FALSE
FETCH
FIELDS
FILE
FILLFACTOR
FILTER
FINAL
FIRST
FLOAT
FLOAT4
FLOAT8
FLOOR
FLUSH
FOLLOWING
FOR
FORCE
FOREIGN
FORTRAN
FORWARD
FOUND
FREE
FREETEXT
FREETEXTTABLE
FREEZE
FROM
FULL
FULLTEXT
FUNCTION
FUSION
G
GENERAL
GENERATED
GET
GLOBAL
GO
GOTO
GRANT
GRANTED
GRANTS
GREATEST
GROUP
GROUPING
HANDLER
HAVING
HEADER
HEAP
HIERARCHY
HIGH_PRIORITY
HOLD
HOLDLOCK
HOST
HOSTS
HOUR
HOUR_MICROSECOND
HOUR_MINUTE
HOUR_SECOND
IDENTIFIED
IDENTITY
IDENTITY_INSERT
IDENTITYCOL
IF
IGNORE
ILIKE
IMMEDIATE
IMMUTABLE
IMPLEMENTATION
IMPLICIT
IN
INCLUDE
INCLUDING
INCREMENT
INDEX
INDICATOR
INFILE
INFIX
INHERIT
INHERITS
INITIAL
INITIALIZE
INITIALLY
INNER
INOUT
INPUT
INSENSITIVE
INSERT
INSERT_ID
INSTANCE
INSTANTIABLE
INSTEAD
INT
INT1
INT2
INT3
INT4
INT8
INTEGER
INTERSECT
INTERSECTION
INTERVAL
INTO
INVOKER
IS
ISAM
ISNULL
ISOLATION
ITERATE
JOIN
K
KEY
KEY_MEMBER
KEY_TYPE
KEYS
KILL
LANCOMPILER
LANGUAGE
LARGE
LAST
LAST_INSERT_ID
LATERAL
LEADING
LEAST
LEAVE
LEFT
LENGTH
LESS
LEVEL
LIKE
LIMIT
LINENO
LINES
LISTEN
LN
LOAD
LOCAL
LOCALTIME
LOCALTIMESTAMP
LOCATION
LOCATOR
LOCK
LOGIN
LOGS
LONG
LONGBLOB
LONGTEXT
LOOP
LOW_PRIORITY
LOWER
M
MAP
MATCH
MATCHED
MAX
MAX_ROWS
MAXEXTENTS
MAXVALUE
MEDIUMBLOB
MEDIUMINT
MEDIUMTEXT
MEMBER
MERGE
MESSAGE_LENGTH
MESSAGE_OCTET_LENGTH
MESSAGE_TEXT
METHOD
MIDDLEINT
MIN
MIN_ROWS
MINUS
MINUTE
MINUTE_MICROSECOND
MINUTE_SECOND
MINVALUE
MLSLABEL
MOD
MODE
MODIFIES
MODIFY
MODULE
MONTH
MONTHNAME
MORE
MOVE
MULTISET
MUMPS
MYISAM
NAME
NAMES
NATIONAL
NATURAL
NCHAR
NCLOB
NESTING
NEW
NEXT
NO
NO_WRITE_TO_BINLOG
NOAUDIT
NOCHECK
NOCOMPRESS
NOCREATEDB
NOCREATEROLE
NOCREATEUSER
NOINHERIT
NOLOGIN
NONCLUSTERED
NONE
NORMALIZE
NORMALIZED
NOSUPERUSER
NOT
NOTHING
NOTIFY
NOTNULL
NOWAIT
NULL
NULLABLE
NULLIF
NULLS
NUMBER
NUMERIC
OBJECT
OCTET_LENGTH
OCTETS
OF
OFF
OFFLINE
OFFSET
OFFSETS
OIDS
OLD
ON
ONLINE
ONLY
OPEN
OPENDATASOURCE
OPENQUERY
OPENROWSET
OPENXML
OPERATION
OPERATOR
OPTIMIZE
OPTION
OPTIONALLY
OPTIONS
OR
ORDER
ORDERING
ORDINALITY
OTHERS
OUT
OUTER
OUTFILE
OUTPUT
OVER
OVERLAPS
OVERLAY
OVERRIDING
OWNER
PACK_KEYS
PAD
PARAMETER
PARAMETER_MODE
PARAMETER_NAME
PARAMETER_ORDINAL_POSITION
PARAMETER_SPECIFIC_CATALOG
PARAMETER_SPECIFIC_NAME
PARAMETER_SPECIFIC_SCHEMA
PARAMETERS
PARTIAL
PARTITION
PASCAL
PASSWORD
PATH
PCTFREE
PERCENT
PERCENT_RANK
PERCENTILE_CONT
PERCENTILE_DISC
PIVOT
PLACING
PLAN
PLI
POSITION
POSTFIX
POWER
PRECEDING
PRECISION
PREFIX
PREORDER
PREPARE
PREPARED
PRESERVE
PRIMARY
PRINT
PRIOR
PRIVILEGES
PROC
PROCEDURAL
PROCEDURE
PROCESS
PROCESSLIST
PUBLIC
PURGE
QUOTE
RAID0
RAISERROR
RANGE
RANK
RAW
READ
READS
READTEXT
REAL
RECHECK
RECONFIGURE
RECURSIVE
REF
REFERENCES
REFERENCING
REGEXP
REGR_AVGX
REGR_AVGY
REGR_COUNT
REGR_INTERCEPT
REGR_R2
REGR_SLOPE
REGR_SXX
REGR_SXY
REGR_SYY
REINDEX
RELATIVE
RELEASE
RELOAD
RENAME
REPEAT
REPEATABLE
REPLACE
REPLICATION
REQUIRE
RESET
RESIGNAL
RESOURCE
RESTART
RESTORE
RESTRICT
RESULT
RETURN
RETURNED_CARDINALITY
RETURNED_LENGTH
RETURNED_OCTET_LENGTH
RETURNED_SQLSTATE
RETURNS
REVERT
REVOKE
RIGHT
RLIKE
ROLE
ROLLBACK
ROLLUP
ROUTINE
ROUTINE_CATALOG
ROUTINE_NAME
ROUTINE_SCHEMA
ROW
ROW_COUNT
ROW_NUMBER
ROWCOUNT
ROWGUIDCOL
ROWID
ROWNUM
ROWS
RULE
SAVE
SAVEPOINT
SCALE
SCHEMA
SCHEMA_NAME
SCHEMAS
SCOPE
SCOPE_CATALOG
SCOPE_NAME
SCOPE_SCHEMA
SCROLL
SEARCH
SECOND
SECOND_MICROSECOND
SECTION
SECURITY
SECURITYAUDIT
SELECT
SELF
SEMANTICKEYPHRASETABLE
SEMANTICSIMILARITYDETAILSTABLE
SEMANTICSIMILARITYTABLE
SENSITIVE
SEPARATOR
SEQUENCE
SERIALIZABLE
SERVER_NAME
SESSION
SESSION_USER
SET
SETOF
SETS
SETUSER
SHARE
SHOW
SHUTDOWN
SIGNAL
SIMILAR
SIMPLE
SIZE
SMALLINT
SOME
SONAME
SOURCE
SPACE
SPATIAL
SPECIFIC
SPECIFIC_NAME
SPECIFICTYPE
SQL
SQL_BIG_RESULT
SQL_BIG_SELECTS
SQL_BIG_TABLES
SQL_CALC_FOUND_ROWS
SQL_LOG_OFF
SQL_LOG_UPDATE
SQL_LOW_PRIORITY_UPDATES
SQL_SELECT_LIMIT
SQL_SMALL_RESULT
SQL_WARNINGS
SQLCA
SQLCODE
SQLERROR
SQLEXCEPTION
SQLSTATE
SQLWARNING
SQRT
SSL
STABLE
START
STARTING
STATE
STATEMENT
STATIC
STATISTICS
STATUS
STDDEV_POP
STDDEV_SAMP
STDIN
STDOUT
STORAGE
STRAIGHT_JOIN
STRICT
STRING
STRUCTURE
STYLE
SUBCLASS_ORIGIN
SUBLIST
SUBMULTISET
SUBSTRING
SUCCESSFUL
SUM
SUPERUSER
SYMMETRIC
SYNONYM
SYSDATE
SYSID
SYSTEM
SYSTEM_USER
TABLE
TABLE_NAME
TABLES
TABLESAMPLE
TABLESPACE
TEMP
TEMPLATE
TEMPORARY
TERMINATE
TERMINATED
TEXT
TEXTSIZE
THAN
THEN
TIES
TIME
TIMESTAMP
TIMEZONE_HOUR
TIMEZONE_MINUTE
TINYBLOB
TINYINT
TINYTEXT
TO
TOAST
TOP
TOP_LEVEL_COUNT
TRAILING
TRAN
TRANSACTION
TRANSACTION_ACTIVE
TRANSACTIONS_COMMITTED
TRANSACTIONS_ROLLED_BACK
TRANSFORM
TRANSFORMS
TRANSLATE
TRANSLATION
TREAT
TRIGGER
TRIGGER_CATALOG
TRIGGER_NAME
TRIGGER_SCHEMA
TRIM
TRUE
TRUNCATE
TRUSTED
TRY_CONVERT
TSEQUAL
TYPE
UESCAPE
UID
UNBOUNDED
UNCOMMITTED
UNDER
UNDO
UNENCRYPTED
UNION
UNIQUE
UNKNOWN
UNLISTEN
UNLOCK
UNNAMED
UNNEST
UNPIVOT
UNSIGNED
UNTIL
UPDATE
UPDATETEXT
UPPER
USAGE
USE
USER
USER_DEFINED_TYPE_CATALOG
USER_DEFINED_TYPE_CODE
USER_DEFINED_TYPE_NAME
USER_DEFINED_TYPE_SCHEMA
USING
UTC_DATE
UTC_TIME
UTC_TIMESTAMP
VACUUM
VALID
VALIDATE
VALIDATOR
VALUE
VALUES
VAR_POP
VAR_SAMP
VARBINARY
VARCHAR
VARCHAR2
VARCHARACTER
VARIABLE
VARIABLES
VARYING
VERBOSE
VIEW
VOLATILE
WAITFOR
WHEN
WHENEVER
WHERE
WHILE
WIDTH_BUCKET
WINDOW
WITH
WITHIN
WITHIN GROUP
WITHOUT
WORK
WRITE
WRITETEXT
X509
XOR
YEAR
YEAR_MONTH
ZEROFILL
ZONE

A list of future keywords which may be introduced in new versions of SQL Server and should be avoided if possible.

ABSOLUTE
ACTION
ADMIN
AFTER
AGGREGATE
ALIAS
ALLOCATE
ARE
ARRAY
ASENSITIVE
ASSERTION
ASYMMETRIC
AT
ATOMIC
BEFORE
BINARY
BIT
BLOB
BOOLEAN
BOTH
BREADTH
CALL
CALLED
CARDINALITY
CASCADED
CAST
CATALOG
CHAR
CHARACTER
CLASS
CLOB
COLLATION
COLLECT
COMPLETION
CONDITION
CONNECT
CONNECTION
CONSTRAINTS
CONSTRUCTOR
CORR
CORRESPONDING
COVAR_POP
COVAR_SAMP
CUBE
CUME_DIST
CURRENT_CATALOG
CURRENT_DEFAULT_TRANSFORM_GROUP
CURRENT_PATH
CURRENT_ROLE
CURRENT_SCHEMA
CURRENT_TRANSFORM_GROUP_FOR_TYPE
CYCLE
DATA
DATE
DAY
DEC
DECIMAL
DEFERRABLE
DEFERRED
DEPTH
DEREF
DESCRIBE
DESCRIPTOR
DESTROY
DESTRUCTOR
DETERMINISTIC
DICTIONARY
DIAGNOSTICS
DISCONNECT
DOMAIN
DYNAMIC
EACH
ELEMENT
END-EXEC
EQUALS
EVERY
EXCEPTION
FALSE
FILTER
FIRST
FLOAT
FOUND
FREE
FULLTEXTTABLE
FUSION
GENERAL
GET
GLOBAL
GO
GROUPING
HOLD
HOST
HOUR
IGNORE
IMMEDIATE
INDICATOR
INITIALIZE
INITIALLY
INOUT
INPUT
INT
INTEGER
INTERSECTION
INTERVAL
ISOLATION
ITERATE
LANGUAGE
LARGE
LAST
LATERAL
LEADING
LESS
LEVEL
LIKE_REGEX
LIMIT
LN
LOCAL
LOCALTIME
LOCALTIMESTAMP
LOCATOR
MAP
MATCH
MEMBER
METHOD
MINUTE
MOD
MODIFIES
MODIFY
MODULE
MONTH
MULTISET
NAMES
NATURAL
NCHAR
NCLOB
NEW
NEXT
NO
NONE
NORMALIZE
NUMERIC
OBJECT
OCCURRENCES_REGEX
OLD
ONLY
OPERATION
ORDINALITY
OUT
OVERLAY
OUTPUT
PAD
PARAMETER
PARAMETERS
PARTIAL
PARTITION
PATH
POSTFIX
PREFIX
PREORDER
PREPARE
PERCENT_RANK
PERCENTILE_CONT
PERCENTILE_DISC
POSITION_REGEX
PRESERVE
PRIOR
PRIVILEGES
RANGE
READS
REAL
RECURSIVE
REF
REFERENCING
REGR_AVGX
REGR_AVGY
REGR_COUNT
REGR_INTERCEPT
REGR_R2
REGR_SLOPE
REGR_SXX
REGR_SXY
REGR_SYY
RELATIVE
RELEASE
RESULT
RETURNS
ROLE
ROLLUP
ROUTINE
ROW
ROWS
SAVEPOINT
SCROLL
SCOPE
SEARCH
SECOND
SECTION
SENSITIVE
SEQUENCE
SESSION
SETS
SIMILAR
SIZE
SMALLINT
SPACE
SPECIFIC
SPECIFICTYPE
SQL
SQLEXCEPTION
SQLSTATE
SQLWARNING
START
STATE
STATEMENT
STATIC
STDDEV_POP
STDDEV_SAMP
STRUCTURE
SUBMULTISET
SUBSTRING_REGEX
SYMMETRIC
SYSTEM
TEMPORARY
TERMINATE
THAN
TIME
TIMESTAMP
TIMEZONE_HOUR
TIMEZONE_MINUTE
TRAILING
TRANSLATE_REGEX
TRANSLATION
TREAT
TRUE
UESCAPE
UNDER
UNKNOWN
UNNEST
USAGE
USING
VALUE
VAR_POP
VAR_SAMP
VARCHAR
VARIABLE
WHENEVER
WIDTH_BUCKET
WITHOUT
WINDOW
WITHIN
WORK
WRITE
XMLAGG
XMLATTRIBUTES
XMLBINARY
XMLCAST
XMLCOMMENT
XMLCONCAT
XMLDOCUMENT
XMLELEMENT
XMLEXISTS
XMLFOREST
XMLITERATE
XMLNAMESPACES
XMLPARSE
XMLPI
XMLQUERY
XMLSERIALIZE
XMLTABLE
XMLTEXT
XMLVALIDATE
YEAR
ZONE