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SQL cheatsheet

· 3 min read
Max Nguyen
FinOps Ranger

SQL Datatype

SQL DatatypeDescription
StringCHAR(size)A fixed-length string containing numbers, letters or special characters. Length may vary from 0-255.
VARCHAR(size)Variable-length string where the length may vary from 0-65535. Similar to CHAR.
TEXT(size)Can contain a string of size up to 65536 bytes.
TINY TEXTCan contain a string of up to 255 characters.
MEDIUM TEXTCan contain a string of up to 16777215 characters.
LONG TEXTCan contain a string of up to 4294967295 characters.
BINARY(size)Similar to CHAR() but stores binary byte strings.
VARBINARY(size)Similar to VARCHAR() but stores binary byte strings.
BLOB(size)Holds blobs up to 65536 bytes.
TINYBLOBIt is used for Binary Large Objects and has a maximum size of 255bytes.
MEDIUMBLOBHolds blobs up to 16777215 bytes.
LONGBLOBHolds blobs up to 4294967295 bytes.
NumbericBIT(size)Bit-value type, where size varies from 1 to 64. Default value: 1
INT(size)Integer with values in the signed range of -2147483648 to 2147483647 and values in the unsigned range of 0 to 4294967295.
TINYINT(size)Integer with values in the signed range of -128 to 127 and values in the unsigned range of 0 to 255.
SMALLINT(size)Integer with values in the signed range of -32768 to 32767 and values in the unsigned range of 0 to 65535.
MEDIUMINT(size)Integer with values in the signed range of -8388608 to 8388607 and values in the unsigned range of 0 to 16777215.
BIGINT(size)Integer with values in the signed range of 9223372036854775808 to 9223372036854775807 and values in the unsigned range of 0 to 18446744073709551615.
BOOLEANBoolean values where 0 is considered as FALSE and non-zero values are considered TRUE.
FLOAT (p)The floating-point number is stored. If the precision parameter is set between 0 to 24, the type is FLOAT() else if it lies between 25 to 53, the datatype is DOUBLE()
Date & TimeDATEStores date in YYYY-MM-DD format with dates in the range of '1000-01-01' to '9999-12-31'.
TIME(fsp)Stores time in hh:mm:ss format with times in the range of '-838:59:59' to '838:59:59'.
DATETIME(fsp)Stores a combination of date and time in YYYY-MM-DD and hh:mm:ss format, with values in the range of '1000-01-01 00:00:00' to '9999-12-31 23:59:59'.
TIMESTAMP(fsp)It stores values relative to the UnixEpoch, basically a Unix Timestamp. Values lie in the range of '1970-01-01 00:00:01' UTC to '2038-01-09 03:14:07' UTC.
YEARStores values of years as a 4digit number format, with a range lying between -1901 to 2155.

SQL Command

SQL Constraints

  • NOT NULL: Specifies that this column cannot store a NULL value.
CREATE TABLE student
(
id INT(8) NOT NULL,
name VARCHAR(30) NOT NULL,
address VARCHAR(50)
);
  • UNIQUE: Specifies that this column can have only Unique values, i.e the values cannot be repeated in the column.
CREATE TABLE Student
(
ID int(8) UNIQUE,
NAME varchar(10) NOT NULL,
ADDRESS varchar(20)
);