SQL Server Function Summary

Aggregate functions

AVG (numeric_expr) returns integer, decimal, money, float --- returns the average value of each value in the group
Count (* | column_name | distinct column_name) returns integer --- number of records in the returned table | returns the number of specified columns | returns the number of different values of the specified Column
Count_big (* | column_name | distinct column_name) returns bigint --- returns the number of records in the table | returns the number of specified columns | returns the number of different values of the specified Column
Max (Express) --- returns the maximum value of the expression
Min (Express) --- returns the minimum value of the expression
Sum (Express) returns integer, decimal, money, float --- returns the sum of all values in the expression or the sum of only non-repeating values
VaR (Express) returns float --- returns the variance of all values in the given expression

Date and Time Functions

Current_timestamp --- returns the current date and time
Dateadd (datepart, number, date_expr) --- return date plus number
Datepart (writing, value, meaning)
YY 1753-March
QQ: 1-4
Mm 1-March December
Dy 1-366
DD 1-31
WK 1-54 weeks
DW 1-7 weeks
HH 0-23 hours
Mi 0-59 minutes
SS 0-59 seconds
MS 0-999 Ms
Datediff (date part <varchar>, start date <datetime>, end date <datetime>) returns datetime --- returns the number of dates and time boundaries across two specified dates
Datename (date part <varchar>, expression <datetime>) returns varchar --- returns a string that represents the specified date part of a specified date
Datepart (date part <varchar>, expression <datetime>) returns integer --- returns an integer that represents the specified date part of the specified date
Day (expression <datetime>) returns integer --- returns the integer that represents the "day" part of the specified date
Getdate () returns datetime --- returns the current system date and time
Getutcdate () returns datetime --- returns the datetime value representing the current UTC time
Isdate (expression <varchar>) returns integer --- determines whether the input expression is a valid date
Month (expression <datetime>) returns integer --- returns the integer representing the "month" part of the specified date
Sysdatetime () returns datetime (7) --- returns the current database system timestamp as the datetime (7) Value
Sysdatetimeoffset () returns datetimeoffset --- returns the current database system timestamp as the datetimeoffset value, which retains the database Time Zone offset
Sysutcdatetime () returns datetime2 (7) --- returns the current database system timestamp (UTC) as the datetime2 (7) Value
Year (expression <datetime>) returns integer --- returns an integer representing the "year" part of the specified date

Mathematical functions

ABS (Express) --- returns the absolute value
ACOs (radian expression <float>) returns float --- returns the angle in radians, and its cosine is a given floating point expression.
Asin (radian expression <float>) returns float --- returns the angle in radians, and its sine is a given floating point expression.
ATIM (radian expression <float>) returns float --- returns the angle in radians, and its positive tangent is the given floating point expression.
Ceiling (expression <exact number or approximate number>) --- returns the smallest integer greater than or equal to the given value expression
Cos (radian expression <float>) returns float --- returns the triangular cosine of the given angle
Cot (radian expression <float>) returns float --- returns the triangle cotangent to the specified angle
Degrees (expression <exact number or approximate number>) --- if the angle is expressed in radians, the corresponding angle expressed in degrees is returned.
Exp (radian expression <float>) returns float --- returns the exponent value of the given floating point expression
Floor (expression <exact number or approximate number>) --- returns the maximum integer less than or equal to the given value expression
Log (radian expression <float>) returns float --- returns the natural logarithm of the given floating-point expression
Log10 (radian expression <float>) returns float --- returns the common logarithm of the given floating-point expression (base-10 logarithm)
Pi () returns float --- returns the constant value of Pi
Power (expression <precise number or approximate number>, power <precise number or approximate number>) --- returns the value of the specified power of a given expression
Radians (degree expression <exact number or approximate number>) --- returns the radians of the corresponding degree expression
Rand (<optional> seed value <integer>) returns float --- returns a random floating point number from 0 to 1
Round (expression <exact number or approximate number>, precision <integer>, <optional> function <integer>) --- returns a value expression, rounded to the specified length or precision
Sign (expression <exact number or approximate number>) --- returns the positive (+ 1), zero (0), or negative (-1) of the given expression)
Sin (radian expression <float>) returns float --- returns the triangular sine of the given angle
SQRT (expression <float>) returns float --- returns the square root of the given expression
Square (expression <float>) returns float --- returns the square of the given expression
Sin (radian expression <float>) returns float --- returns the tangent of the expression

Other functions

Cast (expression as data type) --- convert one data type to another by expression
Coalesce (<unlimited number of parameters> Expression) --- return the first non-null expression in the Parameter
Convert (data type, expression, <optional> date format <smallint>) --- convert one data type to another
Style ID style format
100 or 0 mon dd yyyy hh: miam
101/DD/yy
102 yy. Mm. dd
103 dd/mm/yy
104 dd. mm. yy
105 DD-mm-yy
106 dd mon YY
107 mod DD, YY
108 hh: mm: SS
109 or 9 Mon dd yyyy hh: MI: SS: mmmam
110-dd-yy
111 YY/MM/dd
112 yyyymmdd
113 or 3 dd mon yyyy hh: mm: SS: Mmm (24 h)
114 hh: MI: SS: Mmm (24 h)
120 or 20 yyyy-mm-dd hh: MI: SS (24 h)
121 or 21 yyyy-mm-dd hh: MI: Ss. Mmm (24 h)
126 yyyy-mm-ddthh: mm: SS: Mmm
130 dd mon yyyy hh: MI: SS: mmmam
131 dd/mm/yy hh: MI: SS: mmmam
Datalength (expression) --- returns the number of bytes used to represent the expression
Ident_current (Table Name) --- returns the final id value generated for any session and a specific table in any scope
@ Identity --- return the last generated id value for any table in all scopes of the current session
Isnull (check expression, replace value) --- replace null with the specified replace value
Isnumeric (expression) --- determines whether the expression is a valid value type
Newid () returns uniqueidentifier --- unique value of the uniqueidentifier type
Nullif (expression, expression) if the two are not equivalent, the first expression is returned; otherwise, the return value is null-if the two expressions are equivalent, the return value is null.
@ Rowcount --- returns the number of rows affected by the previous statement.
Rowcount_big () --- returns the number of rows affected by the execution of the previous statement.
Scope_identity () --- returns the last identity value inserted into the same range of identity columns.

String Functions

ASCII (expression) returns integer --- returns the ASCII of the leftmost character in the character expressionCodeValue
Char (tinyint) returns char (1) --- converts an integer ASCII code to a character
Charindex (search expression, expression to be searched, start position) returns integer --- returns the start position of the specified expression in the string
Left (expression <varchar | nvarchar>, number of characters <integer>) --- returns the leftmost specified number of characters in the character expression
Len (expression <varchar | nvarchar>) returns integer --- returns the number of characters in the given string expression
Lower (expression <varchar | nvarchar>) --- returns a character expression that converts uppercase to lowercase.
Ltrim (expression <varchar | nvarchar>) --- returns the character expression after the leading space is deleted.
Nchar (expression <integer>) --- returns Unicode characters with the given integer code
Patindex (search mode text <varchar | nvarchar>, expression to search <varchar | nvarchar>) returns integer --- returns the starting position of the first occurrence of the pattern in the specified expression
Quotename (expression <nvarchar (128)>, <optional> Bootstrap character <char (1)>) returns nvarchar --- returns a unicode string that is added as a valid sqlserver separator identifier
Replace (expression to be searched <varchar | nvarchar>, search expression <varchar | nvarchar>, and replace expression <varchar | nvarchar>) --- replace all the second expressions in the first expression with the third expression
Replicate (expression <varchar | nvarchar>, expression <bigint>) --- repeat character expression by specified number of times
Reverse (expression <varchar | nvarchar>) --- returns the reverse expression of the Character Expression
Right (expression <varchar | nvarchar>, expression <bigint>) --- return the number of characters specified on the right of the Character Expression
Rtrim (expression <varchar | nvarchar>) --- returns the character expression after all trailing spaces are truncated.
Space (expression <integer>) returns char --- returns a string consisting of repeated Spaces
STR (expression <float>, <optional> length <integer>, <optional> decimal places <integer>) returns char --- returns the character expression converted from the numeric expression
Stuff (expression to be searched, start position, number of characters, replacement expression) --- delete a character of the specified length and insert another character group at the specified start point
Substring (expression, start position, length) --- return part of the Character Expression
Unicode (expression) --- returns the Unicode integer of the first character of the expression.
Upper (expression <varchar | nvarchar>) --- returns a character expression that converts lowercase letters to uppercase letters.