A probe into the efficiency of database type space (v)

Next, Test

char (1) default NULL, char (1) NOT null default ', char ($) default NULL, char (+) NOT null default ' '

varchar (1) default NULL, varchar (1) NOT null default ' ', varchar ($) default NULL, varchar (+) NOT null default ' '

nvarchar (1) default null, nvarchar (1) NOT null default ', nvarchar ($) default null, nvarchar (+) NOT null default '

tinyint default NULL, tinyint int NOT null default 0

int default NULL, int not NULL, default 0

Text default NULL, text NOT NULL default '

Table data volume 222,300, occupied space 44.494M

The SQL statement used

Add column: ALTER TABLE t_type add Column New_column char (1) default null;

Modify column: ALTER TABLE t_type modify New_column char ($) default null;

Delete column: ALTER TABLE t_tpye drop column new_column;

View Space:

Select Concat (Round (sum (data_length/1024/1024), 3), ' MB ') as Data_size,
Concat (Round (sum (max_data_length/1024/1024), 3), ' MB ') as Max_data_length,
Concat (Round (sum (data_free/1024/1024), 3), ' MB ') as Data_free,
Concat (Round (sum (index_length/1024/1024), 3), ' MB ') as Index_length
From Information_schema.tables where table_name= ' T_type '

Occupy space	char (1) default null	char (+) default null	char (+) default null	char ($) Default null
Data_size (MB)	45.123	44.922	44.922	44.922
Index_length (MB)	2.256	2.256	2.256	2.256
Data_free (MB)	0	0	0	0
Occupy space	char (1) NOT null default ' '	char (a) NOT null default ' '	char (+) NOT null default ' '	char ($) NOT null default ' '
Data_size (MB)	44.922	44.721	44.721	44.721
Index_length (MB)	2.256	2.256	2.256	2.256
Data_free (MB)	0	0	0	0

New_column char (+) NOT null default ' ' Insert character n a\ Ah
Occupied space \ Number of characters inserted	1 (a\ AH)	2 (aa\ ah AH)	2 (a AH/AH a)	3 (aaa/ah ha)	(a...a/ah ... /full half-width mixing)
Data_size (MB)	45.729\46.733	46.733\48.961	48.961/48.961	48.961/48.961	63.377/66.617/67.617
Index_length (MB)	2.256	2.256	2.256	2.256	2.256
Data_free (MB)	0	0	0	0	4.24

A probe into the efficiency of database type space (v)