Generate AST from simple SQL statements.
$ cat ./statement.sql
SELECT id, name, address FROM users WHERE is_customer IS NOT NULL ORDER BY created;
$ cat ./statement.sql | ./naive-sql-parser > ./statement.dot
$ # Visualize graph:
$ dot -Tpng ./statement.dot > ./statement.pngPlease note that statement.dot file contains graph representation which can be visualized by graphviz:
digraph G {
graph [
label = "INSERT INTO user_notes (id, user_id, note, created) VALUES (1, 1, \"Note 1\", NOW());"
labelloc = t
]
subgraph {
"node_5" [label="insert"]
"node_6" [label="into"]
"node_7" [label="user_notes "]
"node_8" [label="columns"]
"node_9" [label="id"]
"node_10" [label="user_id"]
"node_11" [label="note"]
"node_12" [label="created"]
"node_13" [label="values"]
"node_14" [label="1"]
"node_15" [label="1"]
"node_16" [label="\"Note 1\""]
"node_17" [label="NOW()"]
node_5 -> node_6
node_5 -> node_8
node_5 -> node_13
node_6 -> node_7
node_8 -> node_9
node_8 -> node_10
node_8 -> node_11
node_8 -> node_12
node_13 -> node_14
node_13 -> node_15
node_13 -> node_16
node_13 -> node_17
}
}
Simplified SQL statements are being parsed by a non-deterministic state machine. This machine is documented in doc/state-machine.dot file (see this image).
Put your sql statements in test/queries.sql, one in each line. Run check target to generate .dot graph description files.
$ make check TESTS=tst-sql-parserIn case you also have graphviz installed, you can also visualize the results. Run make check to execute all check targets. This will generate png images from graphs.
$ make check
$ # or make check TESTS=visualize.shVisual Studio 2017 Solution is provided in win32 directory.
- Lexer is naïve. Floating point and signed numbers are not supported. Also support for name literals is minimal;
- Parser does not support complex where clauses. Only one statement is supported. (Having more than one statement requires context, like operator precedence);
- Parser does not support nested queries (insert into x (select from y));
- Parser does not support
HAVING,*and many other features which were not requested; - Semantics is not included (e.g. parser does not care about field and value count match);