Davisbase-SQL DATABASE ENGINE

###A java-based SQL databse engine which support common SQL syntax (syntax checker embedded):

Note: A password-based encryption module embedded.

####Default setting:

Username: root

Password: root

CREATE DATABASE

CREATE DATABASE database_name;

CREATE TABLE

CREATE TABLE table_name (attrName dataType Constraints_List);

INSERT INTO

INSERT INTO table_name (Attr_List) VALUES (Value_List);

or

INSERT INTO table_name VALUES (Value_List);

UPDATE (where clause can be applied to either key or non-key attribute)

UPDATE table_name SET attr1=val1,attr2=val2,... (WHERE condition);

DROP TABLE

DROP TABLE table_name;

SELECT-FROM-WHERE (where clause can be applied to either key or non-key attribute)

SELECT * FROM table_name (WHERE condition);

or

SELECT attr_List FROM table_name (WHERE condition);

USE

USE database_name;

##File Format:

####.tbl is the table file

• databaseHeader:

0x0001: # of byte for magic header

0x0002-0x0013: magic header

0x0014-0x0015: page size

0x0016: most recent version of DBMS that modifies the file

0x0017: most recent version of DBMS that read the file

0x0018: reserved unused space at the end of each page

0x0019: Maximum embedded payload fraction (reserved, currently 64)

0x001A: Minimum embedded payload fraction (reserved, currently 32)

0x001B: Leaf payload fraction (reserved, currently 32)

0x001C-0X001F: file change counter

0x0020-0x0023: file size in pages

0x0024-0x0027: text encoding schema

0x0028-0x003B reserved space

0x003C-0X003F: Davisbase version number

0x0040-0x0043: the version-valid-for number

• page header:

0x00: 0x05 - table interior node; 0x0D - table leaf node

0x01-0x02: start of frist free block in a page (0 if no free block)

0x03-0x04: number of cells in a page

0x05-0x06: start of cell content area

0x07: number of free fragments in a page

0x08-0x0B: right page pointer

0x0C-: cell pointer array

• cell:

leaf page:

0x00: delete marker

0x01-0x02: payload size

0x03-0x06: key value

0x07-0x08: payload header size

0x09- : attribute type code series

following: value of each attribute

interior page:

0x00: delete marker

0x01-0x04: key value

0x05-0x08: page pointer

• Record Format:

Examples: