MySQL CheatSheet

MySQL is an open-source relational database management system. As with other relational databases, MySQL stores data in tables made up of rows and columns. Users can define, manipulate, control, and


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# Getting started MySQL


What is MySQL ?

MySQL is an open-source relational database management system. As with other relational databases, MySQL stores data in tables made up of rows and columns. Users can define, manipulate, control, and query data using Structured Query Language, more commonly known as SQL. MySQLs name is a combination of "My," the name of MySQL creator Michael Wideniuss daughter, and "SQL".

  • MySQL is a database system used on the web
  • MySQL is a database system that runs on a server
  • MySQL is ideal for both small and large applications
  • MySQL is very fast, reliable, and easy to use
  • MySQL uses standard SQL
  • MySQL compiles on a number of platforms
  • MySQL is free to download and use
  • MySQL is developed, distributed, and supported by Oracle Corporation
  • MySQL is named after co-founder Monty Widenius's daughter: My
Also see: MySQL Document

Connect MySQL

mysql -u [username] -p

mysql [db_name]

mysql -h [host] -P [port] -u [username] -p [db_name]

mysql -h [host] -u [username] -p [db_name]

MySQL Backups

# Create a backup
mysqldump -u username -p db_name > database.sql

# Export db without schema
mysqldump -u username -p db_name --no-data=true --add-drop-table=false > database.sql

# Restore a backup
mysql -u username -p db_name < database.sql

MySQL Common Command

Database

- -
create database db ; Create database
show databases; List databases
use db; Switch to db
drop database db; Delete db

Table

- -
show tables; List tables for current db
show fields from t; List fields for a table
desc t; Show table structure
show create table t; Show create table sql
truncate table t; Remove all data in a table
drop table t; Delete table

Proccess

- -
show processlist; List processes
kill pid; kill process

Other

- -
exit or \q Exit MySQL session

# MySQL Data Types


Important Note

Properly defining the fields in a table is important to the overall optimization of your database. You should use only the type and size of field you really need to use.

For example, do not define a field 10 characters wide, if you know you are only going to use 2 characters. These types of fields (or columns) are also referred to as data types, after the type of data you will be storing in those fields.

Note: The data type of a column defines what value the column can hold: integer, character, money, date and time, binary, and so on.

String

CHAR(size) A FIXED length string (can contain letters, numbers, and special characters). The size parameter specifies the column length in characters - can be from 0 to 255. Default is 1
VARCHAR(size) A VARIABLE length string (can contain letters, numbers, and special characters). The size parameter specifies the maximum column length in characters - can be from 0 to 65535
BINARY(size) Equal to CHAR(), but stores binary byte strings. The size parameter specifies the column length in bytes. Default is 1
VARBINARY(size) Equal to VARCHAR(), but stores binary byte strings. The size parameter specifies the maximum column length in bytes.
TINYBLOB For BLOBs (Binary Large OBjects). Max length: 255 bytes
TINYTEXT Holds a string with a maximum length of 255 characters
TEXT(size) Holds a string with a maximum length of 65,535 bytes
BLOB(size) For BLOBs (Binary Large OBjects). Holds up to 65,535 bytes of data
MEDIUMTEXT Holds a string with a maximum length of 16,777,215 characters
MEDIUMBLOB For BLOBs (Binary Large OBjects). Holds up to 16,777,215 bytes of data
LONGTEXT Holds a string with a maximum length of 4,294,967,295 characters
LONGBLOB For BLOBs (Binary Large OBjects). Holds up to 4,294,967,295 bytes of data
ENUM(val1, val2, val3, ...) A string object that can have only one value, chosen from a list of possible values. You can list up to 65535 values in an ENUM list. If a value is inserted that is not in the list, a blank value will be inserted. The values are sorted in the order you enter them
SET(val1, val2, val3, ...) A string object that can have 0 or more values, chosen from a list of possible values. You can list up to 64 values in a SET list

Numeric

- -
TINYINT x Integer (-128 to 127)
SMALLINT x Integer (-32768 to 32767)
MEDIUMINT x Integer (-8388608 to 8388607)
INT x Integer (-2147­483648 to 214748­3647)
BIGINT x Integer (-9223­372­036­854­775808 to 922337­203­685­477­5807)
FLOAT Decimal (precise to 23 digits)
DOUBLE Decimal (24 to 53 digits)
DECIMAL "­DOU­BLE­" stored as string

Date & time

Data Type Format
DATE yyyy-MM-dd
TIME hh:mm:ss
DATETIME yyyy-MM-dd hh:mm:ss
TIMESTAMP yyyy-MM-dd hh:mm:ss
YEAR yyyy

# Functions & Operators MySQL


Strings

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
CHARACTER_LENGTH() Synonym for CHAR_LENGTH()
CHAR_LENGTH() Return number of characters in argument
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() Index (position) of first argument in subsequent arguments
FIND_IN_SET() Index (position) of first argument within second argument
FORMAT() Return a number formatted to specified number of decimal places
FROM_BASE64() Decode base64 encoded string and return result
HEX() Hexadecimal representation of decimal or string value
INSERT() Insert substring at specified position up to 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 Whether string matches regular expression
REGEXP_INSTR() Starting index of substring matching regular expression
REGEXP_LIKE() Whether string matches regular expression
REGEXP_REPLACE() Replace substrings matching regular expression
REGEXP_SUBSTR() Return substring matching regular expression
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 Whether string matches regular expression
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

Date and Time

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() Synonyms for CURDATE()
CURRENT_TIME() Synonyms for CURTIME()
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() Synonym for NOW()
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
GET_FORMAT() '%m.%d.%Y'

Numeric

%, MOD Modulo operator
* Multiplication operator
+ Addition operator
- Minus operator
- Change the sign of the argument
/ Division operator
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
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
MOD() Return the remainder
PI() Return the value of pi
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 argumen
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
TRUNCATE() Truncate to specified number of decimal places

Aggregate

AVG() Return the average value of the argument
BIT_AND() Return bitwise AND
BIT_OR() Return bitwise OR
BIT_XOR() Return bitwise XOR
COUNT() Return a count of the number of rows returned
COUNT(DISTINCT) Return the count of a number of different values
GROUP_CONCAT() Return a concatenated string
JSON_ARRAYAGG() Return result set as a single JSON array
JSON_OBJECTAGG() Return result set as a single JSON object
MAX() Return the maximum value
MIN() Return the minimum value
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
SUM() Return the sum
VAR_POP() Return the population standard variance
VAR_SAMP() Return the sample variance
VARIANCE() Return the population standard variance

Cast

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

Flow Control

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

Information

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
CONNECTION_ID() Return the connection ID (thread ID) for the connection
CURRENT_ROLE() Return the current active roles
CURRENT_USER() The authenticated user name and host name
DATABASE() Return the default (current) database name
FOUND_ROWS() For a SELECT with a LIMIT clause, the number of rows that would be returned were there no LIMIT clause
ICU_VERSION() ICU library version
LAST_INSERT_ID() Value of the AUTOINCREMENT column for the last INSERT
ROLES_GRAPHML() Return a GraphML document representing memory role subgraphs
ROW_COUNT() The number of rows updated
SCHEMA() Synonym for DATABASE()
SESSION_USER() Synonym for USER()
SYSTEM_USER() Synonym for USER()
USER() The user name and host name provided by the client
VERSION() Return a string that indicates the MySQL server version

Encryption and Compression

AES_DECRYPT() Decrypt using AES
AES_ENCRYPT() Encrypt using AES
COMPRESS() Return result as a binary string
MD5() Calculate MD5 checksum
RANDOM_BYTES() Return a random byte vector
SHA1(), SHA() Calculate an SHA-1 160-bit checksum
SHA2() Calculate an SHA-2 checksum
STATEMENT_DIGEST() Compute statement digest hash value
STATEMENT_DIGEST_TEXT() Compute normalized statement digest
UNCOMPRESS() Uncompress a string compressed
UNCOMPRESSED_LENGTH() Return the length of a string before compression
VALIDATE_PASSWORD_STRENGTH() Determine strength of password

Locking

GET_LOCK() Get a named lock
IS_FREE_LOCK() Whether the named lock is free
IS_USED_LOCK() Whether the named lock is in use; return connection identifier if true
RELEASE_ALL_LOCKS() Release all current named locks
RELEASE_LOCK() Release the named lock

Bit

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

Miscellaneous

ANY_VALUE() Suppress ONLY_FULL_GROUP_BY value rejection
BIN_TO_UUID() Convert binary UUID to string
DEFAULT() Return the default value for a table column
GROUPING() Distinguish super-aggregate ROLLUP rows from regular rows
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_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_UUID() Whether argument is a valid UUID
MASTER_POS_WAIT() Block until the replica has read and applied all updates up to the specified position
NAME_CONST() Cause the column to have the given name
SLEEP() Sleep for a number of seconds
UUID() Return a Universal Unique Identifier (UUID)
UUID_SHORT() Return an integer-valued universal identifier
UUID_TO_BIN() Convert string UUID to binary
VALUES() Define the values to be used during an INSERT

Json

-> Return value from JSON column after evaluating path; equivalent to JSON_EXTRACT().
->> Return value from JSON column after evaluating path and unquoting the result; equivalent to JSON_UNQUOTE(JSON_EXTRACT()).
JSON_ARRAY() Create JSON array
JSON_ARRAY_APPEND() Append data to JSON document
JSON_ARRAY_INSERT() Insert into JSON array
JSON_CONTAINS() Whether JSON document contains specific object at path
JSON_CONTAINS_PATH() Whether JSON document contains any data at pat
JSON_DEPTH() Maximum depth of JSON document
JSON_EXTRACT() Return data from JSON document
JSON_INSERT() Insert data into JSON document
JSON_KEYS() Array of keys from JSON document
JSON_LENGTH() Number of elements in JSON document
JSON_MERGE() (deprecated) Merge JSON documents, preserving duplicate keys. Deprecated synonym for JSON_MERGE_PRESERVE()
JSON_MERGE_PATCH() Merge JSON documents, replacing values of duplicate keys
JSON_MERGE_PRESERVE() Merge JSON documents, preserving duplicate keys
JSON_OBJECT() Create JSON object
JSON_OVERLAPS() (introduced 8.0.17) Compares two JSON documents, returns TRUE (1) if these have any key-value pairs or array elements in common, otherwise FALSE (0)
JSON_PRETTY() Print a JSON document in human-readable format
JSON_QUOTE() Quote JSON document
JSON_REMOVE() Remove data from JSON document
JSON_REPLACE() Replace values in JSON document
JSON_SCHEMA_VALID() (introduced 8.0.17) Validate JSON document against JSON schema; returns TRUE/1 if document validates against schema, or FALSE/0 if it does not
JSON_SCHEMA_VALIDATION_REPORT() (introduced 8.0.17) Validate JSON document against JSON schema; returns report in JSON format on outcome on validation including success or failure and reasons for failure
JSON_SEARCH() Path to value within JSON document
JSON_SET() Insert data into JSON document
JSON_STORAGE_FREE() Freed space within binary representation of JSON column value following partial update
JSON_STORAGE_SIZE() Space used for storage of binary representation of a JSON document
JSON_TABLE() Return data from a JSON expression as a relational table
JSON_TYPE() Type of JSON value
JSON_UNQUOTE() Unquote JSON value
JSON_VALID() Whether JSON value is valid
JSON_VALUE() (introduced 8.0.21) Extract value from JSON document at location pointed to by path provided; return this value as VARCHAR(512) or specified type
MEMBER OF() (introduced 8.0.17) Returns true (1) if first operand matches any element of JSON array passed as second operand, otherwise returns false (0)


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