extracting info from LDAP column?

I have a table with one of the columns being ldap info. Example value would be:
ou=FOO,ou=BAR,o=XYZ,dc=WORLD

From this I would like to extract the first string, in this case FOO.

My last attempt was:

which gives me error message:
ERROR 1054 (42S22): Unknown column 'startpos' in 'field list'


1+instr(T.ldap,"=") evaluates to the correct value -- 4 for the example ldap field value on the top
Same with instr(T.ldap,",") -- 7 in the example

And mid(T.ldap,4,7-4) would give me the correct value -- FOO in the example

However, I can not rely on the numbers 4 and 7.

Any suggestions?

re: extracting info from LDAP column?

Use substring() as shown below:

mysql> SELECT SUBSTRING('Quadratically',5);
-> 'ratically'

re: extracting info from LDAP column?

You can not use column aliases in functions, change your query as follows

re: extracting info from LDAP column?

Thanks.
That's what I ended up doing. I just don't like the idea of the same expression being calculated twice.