DRDS 支持的函数分为日期时间函数、字符串函数、转换函数、聚合函数、数学函数、比较函数、位函数、控制流程函数、信息函数、加密和压缩函数以及其他函数；JSON 函数和地理信息函数的下推执行。
以下函数出现在WHERE条件、UPDATE语句中，DRDS不支持：LAST_INSERT_ID()CONNECTION_ID()CURRENT_USER(), CURRENT_USERDATABASE()SCHEMA()USER()VERSION()
与 MySQL5.7 相比，DRDS 不支持以下几类函数：
已经支持的几类函数中，有如下函数不支持：
类别 |
函数名 |
描述 |
日期时间函数 |
CONVERT_TZ() |
Convert from one time zone to another |
GET_FORMAT() |
Return a date format string |
|
LOCALTIME(), LOCALTIME |
Synonym for NOW() |
|
LOCALTIMESTAMP, LOCALTIMESTAMP() |
Synonym for NOW() |
|
字符串函数 |
FIND_IN_SET() |
Return the index position of the first argument within the second argument |
LOAD_FILE() |
Load the named file |
|
MATCH |
Perform full-text search |
|
SOUNDS LIKE |
Compare sounds |
|
聚合函数 |
BIT_AND( |
Return bitwise AND |
BIT_OR() |
Return bitwise OR |
|
BIT_XOR() |
Return bitwise XOR |
|
GROUP_CONCAT() |
Return a concatenated string |
|
STD() |
Return the population standard deviation |
|
STDDEV() |
Return the population standard deviation |
|
STDDEV_POP() |
Return the population standard deviation |
|
STDDEV_SAMP() |
Return the sample standard deviation |
|
VAR_POP() |
Return the population standard variance |
|
VAR_SAMP() |
Return the sample variance |
|
VARIANCE() |
Return the population standard variance |
|
数学函数 |
RADIANS() |
Return argument converted to radians |
信息函数 |
BENCHMARK() |
Repeatedly execute an expression |
CHARSET() |
Return the character set of the argument |
|
COERCIBILITY() |
Return the collation coercibility value of the string argument |
|
COLLATION() |
Return the collation of the string argument |
|
FOUND_ROWS() |
For a SELECT with a LIMIT clause, the number of rows that would be returned were there no LIMIT clause |
|
ROW_COUNT() |
The number of rows updated |
|
加密和压缩函数 |
ASYMMETRIC_DECRYPT() |
Decrypt ciphertext using private or public key |
ASYMMETRIC_DERIVE() |
Derive symmetric key from asymmetric keys |
|
ASYMMETRIC_ENCRYPT() |
Encrypt cleartext using private or public key |
|
ASYMMETRIC_SIGN() |
Generate signature from digest |
|
ASYMMETRIC_VERIFY() |
Verify that signature matches digest |
|
CREATE_ASYMMETRIC_PRIV_KEY() |
Create private key |
|
CREATE_ASYMMETRIC_PUB_KEY() |
Create public key |
|
CREATE_DH_PARAMETERS() |
Generate shared DH secret |
|
CREATE_DIGEST() |
Generate digest from string |
|
DECODE() (deprecated 5.7.2) |
Decodes a string encrypted using ENCODE() |
|
DES_DECRYPT() (deprecated 5.7.6) |
Decrypt a string |
|
DES_ENCRYPT() (deprecated 5.7.6) |
Encrypt a string |
|
ENCODE() (deprecated 5.7.2) |
Encode a string |
|
ENCRYPT() (deprecated 5.7.6) |
Encrypt a string |
|
OLD_PASSWORD() |
Return the value of the pre-4.1 implementation of PASSWORD |
|
PASSWORD() (deprecated 5.7.6) |
Calculate and return a password string |
|
RANDOM_BYTES() |
Return a random byte vector |
|
SHA1(), SHA() |
Calculate an SHA-1 160-bit checksum |
|
SHA2() |
Calculate an SHA-2 checksum |
|
VALIDATE_PASSWORD_STRENGTH() |
Determine strength of password |
|
其他函数 |
ANY_VALUE() |
Suppress ONLY_FULL_GROUP_BY value rejection |
DEFAULT() |
Return the default value for a table column |
|
GET_LOCK() |
Get a named lock |
|
INET_ATON() |
Return the numeric value of an IP address |
|
INET_NTOA() |
Return the IP address from a numeric value |
|
INET6_ATON() |
Return the numeric value of an IPv6 address |
|
INET6_NTOA() |
Return the IPv6 address from a numeric value |
|
IS_FREE_LOCK() |
Whether the named lock is free |
|
IS_IPV4() |
Whether argument is an IPv4 address |
|
IS_IPV4_COMPAT() |
Whether argument is an IPv4-compatible address |
|
IS_IPV4_MAPPED() |
Whether argument is an IPv4-mapped address |
|
IS_IPV6() |
Whether argument is an IPv6 address |
|
IS_USED_LOCK() |
Whether the named lock is in use; return connection identifier if true |
|
MASTER_POS_WAIT() |
Block until the slave has read and applied all updates up to the specified position |
|
NAME_CONST() |
Causes the column to have the given name |
