Change demo for sqlite serialization

As explained in https://github.com/jart/cosmopolitan/pull/436#issuecomment-1164706893 the original use case is not possible with sqlite serialization, as an in-memory database cannot be shared across multiple processes. Thereby, this use case simply creates a backup of the in-memory database created in '.init.lua' and loads it to do a query.

tool/net/demo/.init.lua

@@ -9,35 +9,16 @@ HidePath('/usr/share/ssl/')
 -- LaunchBrowser('/tool/net/demo/index.html')
 
 -- sql database (see sql.lua)
-function StoreSqlite(database, path)
+db = sqlite3.open_memory()
-   local buffer = database:serialize()
+db:exec[[
-   return StoreAsset(path, buffer)
-end
-
-function LoadSqlite(path)
-   local database = sqlite3.open_memory()
-   local buffer = LoadAsset(path)
-   database:deserialize(buffer)
-   return database
-end
-
-database = "database.sqlite3"
--- Check if there is already a database
-if GetAssetSize(database) ~= nil then
-   db = LoadSqlite(database)
-   db:exec[[
-      INSERT INTO test (content) VALUES ('World');
-   ]]
-else
-   db = sqlite3.open_memory()
-   db:exec[[
   CREATE TABLE test (
     id INTEGER PRIMARY KEY,
     content TEXT
   );
-      INSERT INTO test (content) VALUES ('Hello');
+  INSERT INTO test (content) VALUES ('Hello World');
-   ]]
+  INSERT INTO test (content) VALUES ('Hello Lua');
-end
+  INSERT INTO test (content) VALUES ('Hello Sqlite3');
+]]
 
 -- this intercepts all requests if it's defined
 function OnHttpRequest()
@@ -54,11 +35,6 @@ function OnHttpRequest()
    SetHeader('Server', 'redbean!')
 end
 
-function OnServerStop()
-   -- make sure we store the database on exit
-   StoreSqlite(db, database)
-end
-
 function Adder(x, y)
    return x + y
 end

tool/net/demo/sql-backup.lua

@@ -0,0 +1,13 @@
+if GetAssetSize("backup.sqlite3") == nil then
+    Write("no backup exists. call <a href='sql-backupstore.lua'>sql-backupstore.lua</a> first.")
+    return
+end
+
+backup = sqlite3.open_memory()
+buffer = LoadAsset("backup.sqlite3")
+backup:deserialize(buffer)
+
+-- See .init.lua for CREATE TABLE setup.
+for row in backup:nrows("SELECT * FROM test") do
+   Write(row.id.." "..row.content.."<br>")
+end

tool/net/demo/sql-backupstore.lua

@@ -0,0 +1,4 @@
+buffer = db:serialize()
+StoreAsset("backup.sqlite3", buffer)
+
+Write("backup created. size: "..GetAssetSize("backup.sqlite3"))

tool/net/net.mk

@@ -167,6 +167,8 @@ o/tinylinux/tool/net/redbean.com:						\
 o/$(MODE)/tool/net/demo/.init.lua.zip.o						\
 o/$(MODE)/tool/net/demo/.reload.lua.zip.o					\
 o/$(MODE)/tool/net/demo/sql.lua.zip.o						\
+o/$(MODE)/tool/net/demo/sql-backup.lua.zip.o				\
+o/$(MODE)/tool/net/demo/sql-backupstore.lua.zip.o			\
 o/$(MODE)/tool/net/demo/unix-rawsocket.lua.zip.o				\
 o/$(MODE)/tool/net/demo/unix-subprocess.lua.zip.o				\
 o/$(MODE)/tool/net/demo/unix-webserver.lua.zip.o				\
@@ -215,6 +217,8 @@ o/$(MODE)/tool/net/redbean-demo.com.dbg:					\
 		o/$(MODE)/tool/net/largon2.o					\
 		o/$(MODE)/tool/net/net.pkg					\
 		o/$(MODE)/tool/net/demo/sql.lua.zip.o				\
+		o/$(MODE)/tool/net/demo/sql-backup.lua.zip.o			\
+		o/$(MODE)/tool/net/demo/sql-backupstore.lua.zip.o		\
 		o/$(MODE)/tool/net/demo/unix-rawsocket.lua.zip.o		\
 		o/$(MODE)/tool/net/demo/unix-subprocess.lua.zip.o		\
 		o/$(MODE)/tool/net/demo/unix-webserver.lua.zip.o		\