Example 1: sql data types
BIT TINYINT SMALLINT INT BIGINT DECIMAL NUMERIC FLOAT REAL
DATE TIME DATETIME TIMESTAMP YEAR
CHAR VARCHAR TEXT NCHAR NVARCHAR NTEXT
BINARY VARBINARY IMAGE
CLOB BLOB XML JSON
Example 2: data types in sql
• number(num) - whole numbers up to num digits
• number(num,num2) - num whole numbers up to num2 decimals
• char(num) - fixed length character/string
• varchar2(num) - used for varying length data
• date - full date
• currency - used for prices
Example 3: sql data types
CHAR(size)
Fixed length string which can contain letters, numbers and special
characters. The size parameter sets the maximum string length, from
0 – 255 with a default of 1.
VARCHAR(size) Variable length string similar to CHAR(), but with a maximum string
length range from 0 to 65535.
BINARY(size) Similar to CHAR() but stores binary byte strings.
VARBINARY(size) Similar to VARCHAR() but for binary byte strings.
TINYBLOB Holds Binary Large Objects (BLOBs) with a max length of 255 bytes.
TINYTEXT Holds a string with a maximum length of 255 characters. Use
VARCHAR() instead, as it’s fetched much faster.
TEXT(size) Holds a string with a maximum length of 65535 bytes. Again, better to
use VARCHAR().
BLOB(size) Holds Binary Large Objects (BLOBs) with a max length of 65535
bytes.
MEDIUMTEXT Holds a string with a maximum length of 16,777,215 characters.
MEDIUMBLOB Holds Binary Large Objects (BLOBs) with a max length of 16,777,215
bytes.
LONGTEXT Holds a string with a maximum length of 4,294,967,295 characters.
LONGBLOB Holds Binary Large Objects (BLOBs) with a max length of
4,294,967,295 bytes.
ENUM(a, b, c,
etc…)
A string object that only has one value, which is chosen from a list of
values which you define, up to a maximum of 65535 values. If a value
is added which isn’t on this list, it’s replaced with a blank value instead.
Think of ENUM being similar to HTML radio boxes in this regard.
CREATE TABLE tshirts (color ENUM(‘red’, ‘green’,
‘blue’, ‘yellow’, ‘purple’));
SET(a, b, c, etc…)
A string object that can have 0 or more values, which is chosen from a
list of values which you define, up to a maximum of 64 values. Think of
SET being similar to HTML checkboxes in this regard.
Example 4: sql What type is that value?
SELECT TYPEOF(value);
Example 5: sql data types
BIT(size) A bit-value type with a default of 1. The allowed number of bits in a
value is set via the size parameter, which can hold values from 1 to 64.
TINYINT(size)
A very small integer with a signed range of -128 to 127, and an
unsigned range of 0 to 255. Here, the size parameter specifies the
maximum allowed display width, which is 255.
BOOL Essentially a quick way of setting the column to TINYINT with a size of
1. 0 is considered false, whilst 1 is considered true.
BOOLEAN Same as BOOL.
SMALLINT(size)
A small integer with a signed range of -32768 to 32767, and an
unsigned range from 0 to 65535. Here, the size parameter specifies
the maximum allowed display width, which is 255.
MEDIUMINT(size)
A medium integer with a signed range of -8388608 to 8388607,
and an unsigned range from 0 to 16777215. Here, the size parameter
specifies the maximum allowed display width, which is 255.
INT(size)
A medium integer with a signed range of -2147483648 to
2147483647, and an unsigned range from 0 to 4294967295. Here, the
size parameter specifies the maximum allowed display width, which is
255.
INTEGER(size) Same as INT.
BIGINT(size)
A medium integer with a signed range of -9223372036854775808
to 9223372036854775807, and an unsigned range from 0 to
18446744073709551615. Here, the size parameter specifies the
maximum allowed display width, which is 255.
FLOAT(p)
A floating point number value. If the precision (p) parameter is between
0 to 24, then the data type is set to FLOAT(), whilst if its from 25 to 53,
the data type is set to DOUBLE(). This behaviour is to make the storage
of values more efficient.
DOUBLE(size, d)
A floating point number value where the total digits are set by the size
parameter, and the number of digits after the decimal point is set by
the d parameter.
DECIMAL(size, d)
An exact fixed point number where the total number of digits is set by
the size parameters, and the total number of digits after the decimal
point is set by the d parameter.
For size, the maximum number is 65 and the default is 10, whilst for d,
the maximum number is 30 and the default is 10.
DEC(size, d) Same as DECIMAL.