Update of /cvsroot/monetdb/sql
In directory 23jxhf1.ch3.sourceforge.com:/tmp/cvs-serv24991
Added Files:
rel.txt
Log Message:
very .... short documentation for the relational operators and expressions
--- NEW FILE: rel.txt ---
TODO
select and join ops should allow for and/or of expressions
ie we should alway only have a single exp which is and-ed and
or-ed together.
BASETABLE
(card MULTI)
-> exps is list of column expressions (also used for aliases)
-> l (sql_table)
TABLE (card MULTI)
-> exps is list of column expressions (also used for aliases)
-> l table function expression
SELECT (card MULTI or same ...?)
-> exps selection expressions (ie all e_cmp)
-> l is relation
LEFT|RIGHT|FULL
JOIN (card MULTI)
-> exps join expressions (ie all e_cmp)
-> l is left relation
-> r is rigth relation
SEMI/ANTI
(card MULTI)
-> exps join expressions (ie all e_cmp)
-> l is left relation
-> r is rigth relation
UNION|EXCEPT|INTERSECT
(card ATOM, AGGR or MULTI (same card as lower relation))
-> exps is list of projection expressions
-> l is left relation
-> r is rigth relation
PROJECT (card ATOM, AGGR or MULTI (same card as lower relation))
-> exps is list of projection expressions
-> l is relation
-> r optional, is list of order by expressions
GROUPBY (card ATOM (no group by exps), AGGR)
-> exps is list of (groupby and) aggregate expressions
-> l is relation
-> r is list of group by expressions
TOPN (card ATOM, AGGR, or MULTI (same card as lower relation))
-> exps (list) int limit, [ int offset ]
-> l is relation
INSERT|DELETE|UPDATE (card MULTI)
-> l is table to modify
-> r to be inserted/deleted/updated relation
only (UPDATE)
-> exps list of columns to update (ugh) !
Expressions
e_atom (card ATOM)
-> l literal (-> l = atom)
or
-> r parameter ( ->r = varname, ->f = subtype, ->flag = level)
or
-> numbered variable ( ->flag = nr, ->f = subtype)
e_convert
-> l sub expression
-> r list of from and to subtypes
e_cmp
-> l left sub expression
-> r right sub expression
-> flag compare type
( cmp_gt = 0,
cmp_gte = 1,
cmp_lte = 2,
cmp_lt = 3,
cmp_equal = 4,
cmp_notequal = 5,
cmp_notlike = 6,
cmp_like = 7,
cmp_all = 8, cross product
cmp_or = 9 or handling
)
e_func
e_aggr
-> l list of sub expressions (args for the func and aggr)
-> r rank operators the list order by expressions (group by in l)
-> f func / aggr
for aggr
-> flag DISTINCT and NO_NIL could be set
e_column
-> name alias for the expression (ie used by higher expressions)
l,r names of refered expression
-> l optional relation name
-> r expression name
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