mame/3rdparty/lsqlite3/examples/order.lua
2016-11-07 16:12:06 +01:00

122 lines
2.8 KiB
Lua

local sqlite3 = require("lsqlite3")
local db = assert( sqlite3:open_memory() )
assert( db:exec[[
CREATE TABLE customer (
id INTEGER PRIMARY KEY,
name VARCHAR(40)
);
CREATE TABLE invoice (
id INTEGER PRIMARY KEY,
customer INTEGER NOT NULL,
title VARCHAR(80) NOT NULL,
article1 VARCHAR(40) NOT NULL,
price1 REAL NOT NULL,
article2 VARCHAR(40),
price2 REAL
);
CREATE TABLE invoice_overflow (
id INTEGER PRIMARY KEY,
invoice INTEGER NOT NULL,
article VARCHAR(40) NOT NULL,
price REAL NOT NULL
);
INSERT INTO customer VALUES(
1, "Michael" );
INSERT INTO invoice VALUES(
1, 1, "Computer parts", "harddisc", 89.90, "floppy", 9.99 );
INSERT INTO customer VALUES(
2, "John" );
INSERT INTO invoice VALUES(
2, 2, "Somme food", "apples", 2.79, "pears", 5.99 );
INSERT INTO invoice_overflow VALUES(
NULL, 2, "grapes", 6.34 );
INSERT INTO invoice_overflow VALUES(
NULL, 2, "strawberries", 4.12 );
INSERT INTO invoice_overflow VALUES(
NULL, 2, "tomatoes", 6.17 );
INSERT INTO invoice VALUES(
3, 2, "A new car", "Cybercar XL-1000", 65000.00, NULL, NULL );
]] )
local function customer_name(id)
local stmt = db:prepare("SELECT name FROM customer WHERE id = ?")
stmt:bind_values(id)
stmt:step()
local r = stmt:get_uvalues()
stmt:finalize()
return r
end
local function all_invoices()
return db:nrows("SELECT id, customer, title FROM invoice")
end
local function all_articles(invoice)
local function iterator()
local stmt, row
-- Get the articles that are contained in the invoice table itself.
stmt = db:prepare("SELECT article1, price1, article2, price2 FROM invoice WHERE id = ?")
stmt:bind_values(invoice)
stmt:step()
row = stmt:get_named_values()
-- Every Invoice has at least one article.
coroutine.yield(row.article1, row.price1)
-- Maybe the Invoice has a second article?
if row.article2 then
-- Yes, there is a second article, so return it.
coroutine.yield(row.article2, row.price2)
-- When there was an second article, maybe there are even
-- more articles in the overflow table? We will see...
stmt = db:prepare("SELECT article, price FROM invoice_overflow WHERE invoice = ? ORDER BY id")
stmt:bind_values(invoice)
for row in stmt:nrows() do
coroutine.yield(row.article, row.price)
end
end
end
return coroutine.wrap(iterator)
end
for invoice in all_invoices() do
local id = invoice.id
local name = customer_name(invoice.customer)
local title = invoice.title
print()
print("Invoice #"..id..", "..name..": '"..title.."'")
print("----------------------------------------")
for article, price in all_articles(id) do
print( string.format("%20s %8.2f", article, price) )
end
print()
end