I create these table using MySQL :

CREATE TABLE ProcessLog
(
username VARCHAR(30) NOT NULL,
PID INT UNSIGNED NOT NULL,
appPath VARCHAR(100) NOT NULL,
startTime DATETIME NOT NULL,
endTime DATETIME NULL,
UNIQUE (username, PID, startTime),
FOREIGN KEY (username) REFERENCES Users (username) ON DELETE CASCADE,
) TYPE = INNODB;


CREATE TABLE Users
(
username VARCHAR(30) NOT NULL,
email VARCHAR(30) NULL,
handphone VARCHAR(10) NULL,
PRIMARY KEY (username),
password VARCHAR(30) NOT NULL
) TYPE = INNODB;


CREATE TABLE IELog
(
username VARCHAR(30) NOT NULL,
PID INT UNSIGNED NOT NULL,

FOREIGN KEY (username)
REFERENCES Users (username)
ON DELETE CASCADE,

FOREIGN KEY (PID)
REFERENCES ProcessLog (PID)
ON DELETE CASCADE,

startTime DATETIME NOT NULL,
endTime DATETIME NULL,
URL VARCHAR(200) NOT NULL,
PRIMARY KEY (username, PID, startTime)
) TYPE = INNODB;


After adding two table Users and ProcessLog, I add the IELog table but an error msg occured like this :

titan@linux:~/working/database> mysql test < create_users_table.sql
titan@linux:~/working/database> mysql test < create_ProcessLog_table.sql
titan@linux:~/working/database> mysql test < create_IELog_table.sql
ERROR 1005 at line 1: Can't create table './test/IELog.frm' (errno: 150)

Can anyone help me ? Tks a lot.

rewrite your IELog script like this:

CREATE TABLE IELog
(
username VARCHAR(30) NOT NULL,
PID INT UNSIGNED NOT NULL,
startTime DATETIME NOT NULL,
endTime DATETIME NULL,
URL VARCHAR(200) NOT NULL,
PRIMARY KEY (username, PID, startTime),

FOREIGN KEY (username)
REFERENCES Users (username)
ON DELETE CASCADE,

FOREIGN KEY (PID)
REFERENCES ProcessLog (PID)
ON DELETE CASCADE

) TYPE = INNODB;

I don't think you can declare foreign keys in the middle of your field declarations.