If the result length is greater than the server parameter max_allowed_packet, the string value function returns NULL. For operations on the string position, the first position is marked as 1. ASCII (str) returns the ASCII code value of the leftmost character of the str string. If str is a Null String, 0 is returned. If 'str' is NULL, return NULL. M
If the result length is greater than the server parameter max_allowed_packet, the string value function returns NULL. For operations on the string position, the first position is marked as 1. ASCII (str) returns the ASCII code value of the leftmost character of the str string. If str is a Null String, 0 is returned. If 'str' is NULL, return NULL. M
If the result length is greater than the server parametermax_allowed_packet
, String value function returnNULL
.
For operations on the string position, the first position is marked as 1.
-
ASCII(str)
-
Returns a string.
str
ASCII code value of the leftmost character. If
str
Is a null string and returns
0
. If
str
Yes
NULL
, Return
NULL
.
mysql> select ASCII('2'); -> 50mysql> select ASCII(2); -> 50mysql> select ASCII('dx'); -> 100
For more information, see the ORD () function.
-
ORD(str)
-
If the leftmost character of a string 'str' is a multi-byte character
((first byte ASCII code)*256+(second byte ASCII code))[*256+third byte ASCII code...]
Returns the ASCII code value of a character to return the multi-byte code. If the leftmost character is not a multi-byte character. Returns and
ASCII()
The same value returned by the function.
mysql> select ORD('2'); -> 50
-
CONV(N,from_base,to_base)
-
Convert numbers between different digit bases. Return number
N
String number, from
from_base
Base transform
to_base
Base, if any parameter is
NULL
, Return
NULL
. Parameters
N
It is interpreted as an integer, but can be specified as an integer or a string. Minimum base is
2
And the largest base is
36
. If
to_base
Is a negative number,
N
It is considered as a signed number. Otherwise,
N
It is treated as an unsigned number.
CONV
Work with 64-point precision.
mysql> select CONV("a",16,2); -> '1010'mysql> select CONV("6E",18,8); -> '172'mysql> select CONV(-17,10,-18); -> '-H'mysql> select CONV(10+"10"+'10'+0xa,10,10); -> '40'
-
BIN(N)
-
Returns the binary value.
N
In
N
Is a long integer (
BIGINT
) Number, which is equivalent
CONV(N,10,2)
. If
N
Yes
NULL
, Return
NULL
.
mysql> select BIN(12); -> '1100'
-
OCT(N)
-
Returns the octal value.
N
Represents a string in
N
Is a long integer, which is equivalent
CONV(N,10,8)
. If
N
Is NULL, return
NULL
.
mysql> select OCT(12); -> '14'
-
HEX(N)
-
Returns the hexadecimal value.
N
Represents a string.
N
Is a long integer (
BIGINT
) Number, which is equivalent
CONV(N,10,16)
. If
N
Yes
NULL
, Return
NULL
.
mysql> select HEX(255); -> 'FF'
-
CHAR(N,...)
-
CHAR()
Interpreted as an integer and returns a string consisting of ASCII code characters of these integers.
NULL
The value is skipped.
mysql> select CHAR(77,121,83,81,'76'); -> 'MySQL'mysql> select CHAR(77,77.3,'77.3'); -> 'MMM'
-
CONCAT(str1,str2,...)
-
Returns a string from the parameter link. If any parameter is
NULL
, Return
NULL
. There can be more than two parameters. A numeric parameter is converted to an equivalent string.
mysql> select CONCAT('My', 'S', 'QL'); -> 'MySQL'mysql> select CONCAT('My', NULL, 'QL'); -> NULLmysql> select CONCAT(14.3); -> '14.3'
-
LENGTH(str)
-
-
OCTET_LENGTH(str)
-
-
CHAR_LENGTH(str)
-
-
CHARACTER_LENGTH(str)
-
Returns a string.
str
.
mysql> select LENGTH('text'); -> 4mysql> select OCTET_LENGTH('text'); -> 4
Note that for multi-byte characters, its CHAR_LENGTH () is calculated only once.
-
LOCATE(substr,str)
-
-
POSITION(substr IN str)
-
Returns a substring.
substr
In the string
str
The first position that appears, if
substr
Not in
str
And returns
0
.
mysql> select LOCATE('bar', 'foobarbar'); -> 4mysql> select LOCATE('xbar', 'foobar'); -> 0
This function is multi-byte reliable.
-
LOCATE(substr,str,pos)
-
Returns a substring.
substr
In the string
str
The first position that appears, starting from the position
pos
Start. If
substr
Not in
str
And returns
0
.
mysql> select LOCATE('bar', 'foobarbar',5); -> 7
This function is multi-byte reliable.
-
INSTR(str,substr)
-
Returns a substring.
substr
In the string
str
The first position in. This is in the form of two parameters
LOCATE()
Same, except that the parameters are reversed.
mysql> select INSTR('foobarbar', 'bar'); -> 4mysql> select INSTR('xbar', 'foobar'); -> 0
This function is multi-byte reliable.
-
LPAD(str,len,padstr)
-
Returns a string.
str
, Use a string on the left
padstr
Fill
str
Yes
len
Characters long.
mysql> select LPAD('hi',4,'??'); -> '??hi'
-
RPAD(str,len,padstr)
-
Returns a string.
str
, String on the right
padstr
Fill
str
Yes
len
Characters long.
mysql> select RPAD('hi',5,'?'); -> 'hi???'
-
LEFT(str,len)
-
Returns a string.
str
The leftmost area
len
Characters.
mysql> select LEFT('foobarbar', 5); -> 'fooba'
This function is multi-byte reliable.
-
RIGHT(str,len)
-
Returns a string.
str
The rightmost
len
Characters
。
mysql> select RIGHT('foobarbar', 4); -> 'rbar'
This function is multi-byte reliable.