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Last updated: 2021-05-06 17:51:16

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Language Structures

TDSQL for MySQL supports all literal values used by MySQL, including:

String Literals
Numeric Literals
Date and Time Literals
Hexadecimal Literals
Bit-Value Literals
Boolean Literals
NULL Values

String literals

A string literal is a sequence of bytes or characters, enclosed within either single quote ' or double quote " characters. Currently, TDSQL does not support the ANSI_QUOTES SQL mode, so things enclosed with double quote " characters are always interpreted as string literals instead of identifiers.

TDSQL does not support character set introducers, i.e., the format of [_charset_name]'string' [COLLATE collation_name].

TDSQL supports the following escape characters:

\0: an ASCII NUL (X'00') character
\': a single quote (') character
\": a double quote (") character
\b: a backspace character
\n: a newline (linefeed) character
\r: a carriage return character
\t: a tab character
\z: ASCII 26 (Ctrl+Z)
\\: a backslash (\) character
\%: \%
\_: _

Numeric literals

Numeric literals include integer, decimal, and floating-point literals.
Integers are represented as a sequence of digits which may include . as a decimal separator. A numeric literal may be preceded by - or + to indicate a negative or positive value, respectively.
Exact-value numeric literals can be represented as follows: 1, .2, 3.4, -5, -6.78, +9.10.
Scientific notation examples: 1.2E3, 1.2E-3, -1.2E3, -1.2E-3.

Date and time literals

TDSQL supports the following DATE formats:

'YYYY-MM-DD' or 'YY-MM-DD'
'YYYYMMDD' or 'YYMMDD'
YYYYMMDD or YYMMDD

For example, '2012-12-31', '2012/12/31', '2012^12^31', '2012@12@31', '20070523', and '070523'.

TDSQL supports the following DATETIME and TIMESTAMP formats:

'YYYY-MM-DD HH:MM:SS' or 'YY-MM-DD HH:MM:SS'
'YYYYMMDDHHMMSS' or 'YYMMDDHHMMSS'
YYYYMMDDHHMMSS or YYMMDDHHMMSS 

For example, '2012-12-31 11:30:45', '2012^12^31 11+30+45', '2012/12/31 11*30*45', '2012@12@31 11^30^45', and 19830905132800.

Hexadecimal literals

TDSQL supports the following formats:

X'01AF'
X'01af'
x'01AF'
x'01af'
0x01AF
0x01af

Bit-value literals

TDSQL supports the following formats:

b'01'
B'01'
0b01

Boolean literals

The constants TRUE and FALSE evaluate to 1 and 0, respectively. The constant names can be written in any lettercase.

mysql>  SELECT TRUE, true, FALSE, false;
+------+------+-------+-------+
| TRUE | TRUE | FALSE | FALSE |
+------+------+-------+-------+
|    1 |    1 |     0 |     0 |
+------+------+-------+-------+
1 row in set (0.03 sec)

NULL values

The NULL value means no data. NULL can be written in any lettercase. A synonym is \N (case-sensitive).
Be aware that the NULL value is different from values such as 0 for numeric types or the empty string ('') for string types.

Character Sets and Time Zones

TDSQL supports all character sets and collations supported by MySQL.

mysql> show character set;
+----------+---------------------------------+---------------------+--------+
| Charset  | Description                     | Default collation   | Maxlen |
+----------+---------------------------------+---------------------+--------+
| big5     | Big5 Traditional Chinese        | big5_chinese_ci     |      2 |
| dec8     | DEC West European               | dec8_swedish_ci     |      1 |
| cp850    | DOS West European               | cp850_general_ci    |      1 |
| hp8      | HP West European                | hp8_english_ci      |      1 |
| koi8r    | KOI8-R Relcom Russian           | koi8r_general_ci    |      1 |
| latin1   | cp1252 West European            | latin1_swedish_ci   |      1 |
| latin2   | ISO 8859-2 Central European     | latin2_general_ci   |      1 |
| swe7     | 7bit Swedish                    | swe7_swedish_ci     |      1 |
| ascii    | US ASCII                        | ascii_general_ci    |      1 |
| ujis     | EUC-JP Japanese                 | ujis_japanese_ci    |      3 |
| sjis     | Shift-JIS Japanese              | sjis_japanese_ci    |      2 |
| hebrew   | ISO 8859-8 Hebrew               | hebrew_general_ci   |      1 |
| tis620   | TIS620 Thai                     | tis620_thai_ci      |      1 |
| euckr    | EUC-KR Korean                   | euckr_korean_ci     |      2 |
| koi8u    | KOI8-U Ukrainian                | koi8u_general_ci    |      1 |
| gb2312   | GB2312 Simplified Chinese       | gb2312_chinese_ci   |      2 |
| greek    | ISO 8859-7 Greek                | greek_general_ci    |      1 |
| cp1250   | Windows Central European        | cp1250_general_ci   |      1 |
| gbk      | GBK Simplified Chinese          | gbk_chinese_ci      |      2 |
| latin5   | ISO 8859-9 Turkish              | latin5_turkish_ci   |      1 |
| armscii8 | ARMSCII-8 Armenian              | armscii8_general_ci |      1 |
| utf8     | UTF-8 Unicode                   | utf8_general_ci     |      3 |
| ucs2     | UCS-2 Unicode                   | ucs2_general_ci     |      2 |
| cp866    | DOS Russian                     | cp866_general_ci    |      1 |
| keybcs2  | DOS Kamenicky Czech-Slovak      | keybcs2_general_ci  |      1 |
| macce    | Mac Central European            | macce_general_ci    |      1 |
| macroman | Mac West European               | macroman_general_ci |      1 |
| cp852    | DOS Central European            | cp852_general_ci    |      1 |
| latin7   | ISO 8859-13 Baltic              | latin7_general_ci   |      1 |
| utf8mb4  | UTF-8 Unicode                   | utf8mb4_general_ci  |      4 |
| cp1251   | Windows Cyrillic                | cp1251_general_ci   |      1 |
| utf16    | UTF-16 Unicode                  | utf16_general_ci    |      4 |
| utf16le  | UTF-16LE Unicode                | utf16le_general_ci  |      4 |
| cp1256   | Windows Arabic                  | cp1256_general_ci   |      1 |
| cp1257   | Windows Baltic                  | cp1257_general_ci   |      1 |
| utf32    | UTF-32 Unicode                  | utf32_general_ci    |      4 |
| binary   | Binary pseudo charset           | binary              |      1 |
| geostd8  | GEOSTD8 Georgian                | geostd8_general_ci  |      1 |
| cp932    | SJIS for Windows Japanese       | cp932_japanese_ci   |      2 |
| eucjpms  | UJIS for Windows Japanese       | eucjpms_japanese_ci |      3 |
| gb18030  | China National Standard GB18030 | gb18030_chinese_ci  |      4 |
+----------+---------------------------------+---------------------+--------+
41 rows in set (0.02 sec)

View character sets of the current connection:

mysql> show variables like "%char%";
+--------------------------+-----------------------------------------------------+
| Variable_name            | Value                                               |
+--------------------------+-----------------------------------------------------+
| character_set_client     | latin1                                              |
| character_set_connection | latin1                                              |
| character_set_database   | utf8                                                |
| character_set_filesystem | binary                                              |
| character_set_results    | latin1                                              |
| character_set_server     | utf8                                                |
| character_set_system     | utf8                                                |
| character_sets_dir       | /data/tdsql_run/8812/percona-5.7.17/share/charsets/ |
+--------------------------+-----------------------------------------------------+

Set character sets of the current connection:

mysql> set names utf8;
Query OK, 0 rows affected (0.03 sec)

mysql> show variables like "%char%";
+--------------------------+-----------------------------------------------------+
| Variable_name            | Value                                               |
+--------------------------+-----------------------------------------------------+
| character_set_client     | utf8                                                |
| character_set_connection | utf8                                                |
| character_set_database   | utf8                                                |
| character_set_filesystem | binary                                              |
| character_set_results    | utf8                                                |
| character_set_server     | utf8                                                |
| character_set_system     | utf8                                                |
| character_sets_dir       | /data/tdsql_run/8811/percona-5.7.17/share/charsets/ |
+--------------------------+-----------------------------------------------------+

Note：
TDSQL does not support setting global parameters which can only be set by calling frontend APIs.

Support modifying time zone attributes by setting the time_zone variable.

mysql> show variables like '%time_zone%';
+------------------+--------+
| Variable_name    | Value  |
+------------------+--------+
| system_time_zone | CST    |
| time_zone        | SYSTEM |
+------------------+--------+
2 rows in set (0.00 sec)

mysql> create table test.tt (ts timestamp, dt datetime,c int) shardkey=c;
Query OK, 0 rows affected (0.49 sec)

mysql>  insert into test.tt (ts,dt,c)values ('2017-10-01 12:12:12', '2017-10-01 12:12:12',1);
Query OK, 1 row affected (0.09 sec)

mysql> select * from test.tt;
+---------------------+---------------------+------+
| ts                  | dt                  | c    |
+---------------------+---------------------+------+
| 2017-10-01 12:12:12 | 2017-10-01 12:12:12 |    1 |
+---------------------+---------------------+------+
1 row in set (0.04 sec)

mysql> set time_zone = '+12:00';
Query OK, 0 rows affected (0.00 sec)

mysql> show variables like '%time_zone%';
+------------------+--------+
| Variable_name    | Value  |
+------------------+--------+
| system_time_zone | CST    |
| time_zone        | +12:00 |
+------------------+--------+
2 rows in set (0.00 sec)

mysql> select * from test.tt;
+---------------------+---------------------+------+
| ts                  | dt                  | c    |
+---------------------+---------------------+------+
| 2017-10-01 16:12:12 | 2017-10-01 12:12:12 |    1 |
+---------------------+---------------------+------+
1 row in set (0.06 sec)

Data Types

TDSQL supports all data types supported by MySQL, including numbers, strings, date and time, spatial types, and JSON.

Numbers

For integer types, INTEGER, INT, SMALLINT, TINYINT, MEDIUMINT, and BIGINT are supported.

Type	Bytes	Minimum Value (Signed/Unsigned)	Maximum Value (Signed/Unsigned)
TINYINT	1	-128/0	127/255
SMALLINT	2	-32768/0	32767/65535
MEDIUMINT	3	-8388608/0	8388607/16777215
INT	4	-2147483648/0	2147483647/4294967295
BIGINT	8	-9223372036854775808/0	9223372036854775807/18446744073709551615

For floating-point types, FLOAT and DOUBLE are supported in the format of FLOAT(M,D), REAL(M,D), or DOUBLE PRECISION(M,D).

For fixed-point types, DECIMAL and NUMERIC are supported in the format of DECIMAL(M,D).

Strings

TDSQL supports the following string types:

CHAR and VARCHAR
BINARY and VARBINARY
BLOB and TEXT
    TINYBLOB, TINYTEXT, MEDIUMBLOB, MEDIUMTEXT, LONGBLOB, and LONGTEXT
ENUM
SET

Date and time

TDSQL supports the following date and time types:

DATE, DATETIME, and TIMESTAMP
TIME
YEAR

Spatial data

TDSQL supports the following spatial types:

GEOMETRY
POINT
LINESTRING
POLYGON

MULTIPOINT
MULTILINESTRING
MULTIPOLYGON
GEOMETRYCOLLECTION

JSON

TDSQL supports storing data in JSON format, making JSON processing more efficient while ensuring that errors can be detected in advance.

Note：
You cannot sort JSON values of different types. For example, you cannot compare JSON values of STRING type with those of INTEGER type. For JSON values of the same type, only numbers and strings can be compared and sorted. In the table created by the following SQL statements, the statement select * from t1 order by t1->"$.key2" is not supported because the column sorted by the ORDER BY clause contains both numbers and strings.

mysql>  CREATE TABLE t1 (jdoc JSON,a int) shardkey=a;
Query OK, 0 rows affected (0.30 sec)

mysql> INSERT INTO t1 (jdoc,a)VALUES('{"key1": "value1", "key2": "value2"}',1);
Query OK, 1 row affected (0.00 sec)

mysql> INSERT INTO t1 (jdoc,a)VALUES('{"key1": "value1", "key2": 2}',2);

mysql> INSERT INTO t1 (jdoc,a)VALUES('[1, 2,',5);
ERROR 3140 (22032): Invalid JSON text: "Invalid value." at position 6 in value for column 't1.jdoc'.

mysql> select * from t1;
+--------------------------------------+---+
| jdoc                                 | a |
+--------------------------------------+---+
| {"key1": "value1", "key2": "value2"} | 1 |
| {"key1": "value1", "key2": 2}        | 2 |
+--------------------------------------+---+
2 rows in set (0.00 sec)

Supported Functions

Control Flow Functions

Name	Description
CASE	Case operator
IF()	If/else construct
IFNULL()	Null if/else construct
NULLIF()	Return NULL if expr1 = expr2

String Functions

Name	Description
ASCII()	Return numeric value of left-most character
BIN()	Return a string containing binary representation of a number
BIT_LENGTH()	Return length of argument in bits
CHAR()	Return the character for each integer passed
CHAR_LENGTH()	Return number of characters in argument
CHARACTER_LENGTH()	Synonym for CHAR_LENGTH()
CONCAT()	Return concatenated string
CONCAT_WS()	Return concatenate with separator
ELT()	Return string at index number
EXPORT_SET()	Return a string such that for every bit set in the value bits, you get an on string and for every unset bit, you get an off string
FIELD()	Return the index (position) of the first argument in the subsequent arguments
FIND_IN_SET()	Return the index position of the first argument within the second argument
FORMAT()	Return a number formatted to specified number of decimal places
FROM_BASE64()	Decode to a base-64 string and return result
HEX()	Return a hexadecimal representation of a decimal or string value
INSERT()	Insert a substring at the specified position up to the specified number of characters
INSTR()	Return the index of the first occurrence of substring
LCASE()	Synonym for LOWER()
LEFT()	Return the leftmost number of characters as specified
LENGTH()	Return the length of a string in bytes
LIKE	Simple pattern matching
LOAD_FILE()	Load the named file
LOCATE()	Return the position of the first occurrence of substring
LOWER()	Return the argument in lowercase
LPAD()	Return the string argument, left-padded with the specified string
LTRIM()	Remove leading spaces
MAKE_SET()	Return a set of comma-separated strings that have the corresponding bit in bits set
MATCH	Perform full-text search
MID()	Return a substring starting from the specified position
NOT LIKE	Negation of simple pattern matching
NOT REGEXP	Negation of REGEXP
OCT()	Return a string containing octal representation of a number
OCTET_LENGTH()	Synonym for LENGTH()
ORD()	Return character code for leftmost character of the argument
POSITION()	Synonym for LOCATE()
QUOTE()	Escape the argument for use in an SQL statement
REGEXP	Pattern matching using regular expressions
REPEAT()	Repeat a string the specified number of times
REPLACE()	Replace occurrences of a specified string
REVERSE()	Reverse the characters in a string
RIGHT()	Return the specified rightmost number of characters
RLIKE	Synonym for REGEXP
RPAD()	Append string the specified number of times
RTRIM()	Remove trailing spaces
SOUNDEX()	Return a soundex string
SOUNDS LIKE	Compare sounds
SPACE()	Return a string of the specified number of spaces
STRCMP()	Compare two strings
SUBSTR()	Return the substring as specified
SUBSTRING()	Return the substring as specified
SUBSTRING_INDEX()	Return a substring from a string before the specified number of occurrences of the delimiter
TO_BASE64()	Return the argument converted to a base-64 string
TRIM()	Remove leading and trailing spaces
UCASE()	Synonym for UPPER()
UNHEX()	Return a string containing hex representation of a number
UPPER()	Convert to uppercase
WEIGHT_STRING()	Return the weight string for a string

Numeric Functions and Operators

Name	Description
ABS()	Return the absolute value
ACOS()	Return the arc cosine
ASIN()	Return the arc sine
ATAN()	Return the arc tangent
ATAN2(), ATAN()	Return the arc tangent of the two arguments
CEIL()	Return the smallest integer value not less than the argument
CEILING()	Return the smallest integer value not less than the argument
CONV()	Convert numbers between different number bases
COS()	Return the cosine
COT()	Return the cotangent
CRC32()	Compute a cyclic redundancy check value
DEGREES()	Convert radians to degrees
DIV	Integer division
/	Division operator
EXP()	Raise to the power of
FLOOR()	Return the largest integer value not greater than the argument
LN()	Return the natural logarithm of the argument
LOG()	Return the natural logarithm of the first argument
LOG10()	Return the base-10 logarithm of the argument
LOG2()	Return the base-2 logarithm of the argument
-	Minus operator
MOD()	Return the remainder
%, MOD	Modulo operator
PI()	Return the value of pi
+	Addition operator
POW()	Return the argument raised to the specified power
POWER()	Return the argument raised to the specified power
RADIANS()	Return argument converted to radians
RAND()	Return a random floating-point value
ROUND()	Round the argument
SIGN()	Return the sign of the argument
SIN()	Return the sine of the argument
SQRT()	Return the square root of the argument
TAN()	Return the tangent of the argument
*	Multiplication operator
TRUNCATE()	Truncate to specified number of decimal places
-	Change the sign of the argument

Date and Time Functions

Name	Description
ADDDATE()	Add time values (intervals) to a date value
ADDTIME()	Add time
CONVERT_TZ()	Convert from one time zone to another
CURDATE()	Return the current date
CURRENT_DATE(), CURRENT_DATE	Synonyms for CURDATE()
CURRENT_TIME(), CURRENT_TIME	Synonyms for CURTIME()
CURRENT_TIMESTAMP(), CURRENT_TIMESTAMP	Synonyms for NOW()
CURTIME()	Return the current time
DATE()	Extract the date part of a date or datetime expression
DATE_ADD()	Add time values (intervals) to a date value
DATE_FORMAT()	Format date as specified
DATE_SUB()	Subtract a time value (interval) from a date
DATEDIFF()	Subtract two dates
DAY()	Synonym for DAYOFMONTH()
DAYNAME()	Return the name of the weekday
DAYOFMONTH()	Return the day of the month (0-31)
DAYOFWEEK()	Return the weekday index of the argument
DAYOFYEAR()	Return the day of the year (1-366)
EXTRACT()	Extract part of a date
FROM_DAYS()	Convert a day number to a date
FROM_UNIXTIME()	Format Unix timestamp as a date
GET_FORMAT()	Return a date format string
HOUR()	Extract the hour
LAST_DAY	Return the last day of the month for the argument
LOCALTIME(), LOCALTIME	Synonym for NOW()
LOCALTIMESTAMP, LOCALTIMESTAMP()	Synonym for NOW()
MAKEDATE()	Create a date from the year and day of year
MAKETIME()	Create time from hour, minute, second
MICROSECOND()	Return the microseconds from argument
MINUTE()	Return the minute from the argument
MONTH()	Return the month from the date passed
MONTHNAME()	Return the name of the month
NOW()	Return the current date and time
PERIOD_ADD()	Add a period to a year-month
PERIOD_DIFF()	Return the number of months between periods
QUARTER()	Return the quarter from a date argument
SEC_TO_TIME()	Converts seconds to 'HH:MM:SS' format
SECOND()	Return the second (0-59)
STR_TO_DATE()	Convert a string to a date
SUBDATE()	Synonym for DATE_SUB() when invoked with three arguments
SUBTIME()	Subtract times
SYSDATE()	Return the time at which the function executes
TIME()	Extract the time portion of the expression passed
TIME_FORMAT()	Format as time
TIME_TO_SEC()	Return the argument converted to seconds
TIMEDIFF()	Subtract time
TIMESTAMP()	With a single argument, this function returns the date or datetime expression; with two arguments, the sum of the arguments
TIMESTAMPADD()	Add an interval to a datetime expression
TIMESTAMPDIFF()	Subtract an interval from a datetime expression
TO_DAYS()	Return the date argument converted to days
TO_SECONDS()	Return the date or datetime argument converted to seconds since Year 0
UNIX_TIMESTAMP()	Return a Unix timestamp
UTC_DATE()	Return the current UTC date
UTC_TIME()	Return the current UTC time
UTC_TIMESTAMP()	Return the current UTC date and time
WEEK()	Return the week number
WEEKDAY()	Return the weekday index
WEEKOFYEAR()	Return the calendar week of the date (1-53)
YEAR()	Return the year
YEARWEEK()	Return the year and week

Aggregate (GROUP BY) Functions

Name	Description
AVG()	Return the average value of the argument
COUNT()	Return a count of the number of rows returned
MAX()	Return the maximum value
MIN()	Return the minimum value
SUM()	Return the sum

Bit Functions and Operators

Name	Description
BIT_COUNT()	Return the number of bits that are set
&	Bitwise AND
~	Bitwise inversion
\	Bitwise OR
^	Bitwise XOR
<<	Left shift
>>	Right shift

Cast Functions and Operators

Name	Description
BINARY	Cast a string to a binary string
CAST()	Cast a value as a certain type
CONVERT()	Cast a value as a certain type

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Recent Pages

Compatibility

Language Structures

String literals

Numeric literals

Date and time literals

Hexadecimal literals

Bit-value literals

Boolean literals

NULL values

Character Sets and Time Zones

Data Types

Numbers

Strings

Date and time

Spatial data

JSON

Supported Functions

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Recent Pages

Compatibility

Language Structures

String literals

Numeric literals

Date and time literals

Hexadecimal literals

Bit-value literals

Boolean literals

NULL values

Character Sets and Time Zones

Data Types

Numbers

Strings

Date and time

Spatial data

JSON

Supported Functions

Was this page helpful?

Was this page helpful?