你好，能否同我讲解一下JIVE中的几个表的字段作用

CREATE TABLE jiveGroup (

groupID INT NOT NULL,

name VARCHAR(100) NOT NULL,

description VARCHAR(255) NULL,

modifiedDate CHAR(15) NOT NULL,

creationDate CHAR(15) NOT NULL,

);

CREATE TABLE jiveGroupPerm (

forumID INT NOT NULL,

groupID INT NOT NULL,

permission INT NOT NULL,);

CREATE TABLE jiveGroupProp (

groupID INT NOT NULL,

name VARCHAR(100) NOT NULL,

propValue TEXT NOT NULL,

);

CREATE TABLE jiveGroupUser (

groupID INT NOT NULL,

userID INT NOT NULL,

administrator INT NOT NULL,

);