JDBC 驱动开发准则（ Driver Guidelines ）

ABS(number)

Absolute value of number

ACOS(float)

Arccosine, in radians, of float

ASIN(float)

Arcsine, in radians, of float

ATAN(float)

Arctangent, in radians, of float

ATAN2(float1, float2)

Arctangent, in radians, of float2 / float1

CEILING(number)

Smallest integer >= number

COS(float)

Cosine of float radians

COT(float)

Cotangent of float radians

DEGREES(number)

Degrees in number radians

EXP(float)

Exponential function of float

FLOOR(number)

Largest integer <= number

LOG(float)

Base e logarithm of float

LOG10(float)

Base 10 logarithm of float

MOD(integer1, integer2)

Remainder for integer1 / integer2

PI()

The constant pi

POWER(number, power)

number raised to (integer) power

RADIANS(number)

Radians in number degrees

RAND(integer)

Random floating point for seed integer

ROUND(number, places)

number rounded to places places

SIGN(number)

・ to indicate number is < 0;

0 to indicate number is = 0;

1 to indicate number is > 0

SIN(float)

Sine of float radians

SQRT(float)

Square root of float

TAN(float)

Tangent of float radians

TRUNCATE(number, places)

number truncated to places places

ASCII(string)

Integer representing the ASCII code value of the leftmost character in string

CHAR(code)

Character with ASCII code value code , where code is between 0 and 255

CONCAT(string1, string2)

Character string formed by appending string2 to string1 ; if a string is null, the result is DBMS-dependent

DIFFERENCE(string1, string2)

Integer indicating the difference between the values returned by the function SOUNDEX for string1 and string2

INSERT(string1, start, length, string2)

A character string formed by deleting length characters from string1 beginning at start , and inserting string2 into string1 at start

LCASE(string)

Converts all uppercase characters in string to lowercase

LEFT(string, count)

The count leftmost characters from string

LENGTH(string)

Number of characters in string , excluding trailing blanks

LOCATE(string1, string2[, start])

Position in string2 of the first occurrence of string1 , searching from the beginning of string2 ; if start is specified, the search begins from position start . 0 is returned if string2 does not contain string1 . Position 1 is the first character in string2 .

LTRIM(string)

Characters of string with leading blank spaces removed

REPEAT(string, count)

A character string formed by repeating string count times

REPLACE(string1, string2, string3)

Replaces all occurrences of string2 in string1 with string3

RIGHT(string, count)

The count rightmost characters in string

RTRIM(string)

The characters of string with no trailing blanks

SOUNDEX(string)

A character string, which is data source-dependent, representing the sound of the words in string ; this could be a four-digit SOUNDEX code, a phonetic representation of each word, etc.

SPACE(count)

A character string consisting of count spaces

SUBSTRING(string, start, length)

A character string formed by extracting length characters from string beginning at start

UCASE(string)

Converts all lowercase characters in string to uppercase

CURDATE()

The current date as a date value

CURTIME()

The current local time as a time value

DAYNAME(date)

A character string representing the day component of date ; the name for the day is specific to the data source

DAYOFMONTH(date)

An integer from 1 to 31 representing the day of the month in date

DAYOFWEEK(date)

An integer from 1 to 7 representing the day of the week in date ; 1 represents Sunday

DAYOFYEAR(date)

An integer from 1 to 366 representing the day of the year in date

HOUR(time)

An integer from 0 to 23 representing the hour component of time

MINUTE(time)

An integer from 0 to 59 representing the minute component of time

MONTH(date)

An integer from 1 to 12 representing the month component of date

MONTHNAME(date)

A character string representing the month component of date ; the name for the month is specific to the data source

NOW()

A timestamp value representing the current date and time

QUARTER(date)

An integer from 1 to 4 representing the quarter in date ; 1 represents January 1 through March 31

SECOND(time)

An integer from 0 to 59 representing the second component of time

TIMESTAMPADD(interval, count, timestamp)

A timestamp calculated by adding count number of interval (s) to timestamp ; interval may be one of the following: SQL_TSI_FRAC_SECOND , SQL_TSI_SECOND , SQL_TSI_MINUTE , SQL_TSI_HOUR , SQL_TSI_DAY , SQL_TSI_WEEK , SQL_TSI_MONTH , SQL_TSI_QUARTER , or SQL_TSI_YEAR

TIMESTAMPDIFF(interval, timestamp1, timestamp2)

An integer representing the number of interval (s) by which timestamp2 is greater than timestamp1 ; interval may be one of the following: SQL_TSI_FRAC_SECOND , SQL_TSI_SECOND , SQL_TSI_MINUTE , SQL_TSI_HOUR , SQL_TSI_DAY , SQL_TSI_WEEK , SQL_TSI_MONTH , SQL_TSI_QUARTER , or SQL_TSI_YEAR

WEEK(date)

An integer from 1 to 53 representing the week of the year in date

YEAR(date)

An integer representing the year component of date

DATABASE()

Name of the database

IFNULL(expression, value)

value if expression is null ; expression if expression is not null

USER()

User name in the DBMS

CONVERT(value, SQLtype)

value converted to SQLtype where SQLtype may be one of the following SQL types: BIGINT , BINARY , BIT , CHAR , DATE , DECIMAL , DOUBLE , FLOAT , INTEGER , LONGVARBINARY , LONGVARCHAR , REAL , SMALLINT , TIME , TIMESTAMP , TINYINT , VARBINARY , or VARCHAR