This command will change the job class of the invoking character.

jobchange 1; // This would change your player into a Swordman
jobchange 4002; // This would change your player into a Swordman High

This command does work with numbers, but you can also use job names. The full
list of job names and the numbers they correspond to can be found in
'db/const.txt'.

// This would change your player into a Swordman
jobchange Job_Swordman;
// This would change your player into a Swordman High
jobchange Job_Swordman_High;

'upper flag' can alternatively be used to specify the type of job one changes
to. For example, jobchange Job_Swordman,1; will change the character to a high
swordsman. The upper values are:
-1 (or when omitted): preserves the current job type.
0: Normal/standard classes
1: High/Advanced classes
2: Baby classes

This command will also set a permanent character-based variable
'jobchange_level' which will contain the job level at the time right before
changing jobs, which can be checked for later in scripts.