How to find an AR System Field?

AR System usually does not provide you a simple method for field search. You need to enable "Object Relationships" in Server Information form. However this puts load on AR Server on large-scaled production environments and usually kept as disabled. What I would propose is to find the fields on database level. The query I use is below:
SELECT A.NAME, F.fieldname, f.fieldid, FC.pattern, fc.maxlength
FROM FIELD F, ARSCHEMA A, FIELD_CHAR FC
WHERE F.SCHEMAID = A.SCHEMAID 
AND (F.fieldid = fc.fieldid AND FC.schemaid = A.schemaid)
AND F.fieldname LIKE '%FieldName%'
order by A.name, F.fieldname
You should put the name of the field instead of "FieldName". The query is used only for character fields but you can adjust it according to the other field types. If you would like to search by Field ID, you can use the below query:
SELECT A.NAME, F.fieldname, f.fieldid, FC.pattern, fc.maxlength
FROM FIELD F, ARSCHEMA A, FIELD_CHAR FC
WHERE F.SCHEMAID = A.SCHEMAID 
AND (F.fieldid = fc.fieldid AND FC.schemaid = A.schemaid)
AND F.fieldid = 666666673
order by F.fieldname