SQLite
SQLite 是使用 C 语言实现的一款轻量 SQL 数据库引擎。RuxOS 支持了 SQLite，并针对常用 SQL 语句进行了测试，除了 SQL 语句的正确性测试以外，还能借助块设备进行数据持久化。
运行命令
通过在 RuxOS 根目录执行下面命令，可以基于 ruxlibc 运行起来 SQLite。
make A=apps/c/sqlite3/ LOG=error BLK=y run
参数解释：
-
A：SQLite 的测试程序 main 函数所在目录路径。 -
LOG：运行的日志等级，不同的日志等级能够打印出不同的调试信息。 -
BLK：使用块设备进行数据持久化。
运行结果
一个可能的运行结果如下所示：
SeaBIOS (version rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org)
iPXE (http://ipxe.org) 00:02.0 CA00 PCI2.10 PnP PMM+7EFD0AA0+7EF30AA0 CA00
Booting from ROM..
Initialize IDT & GDT...
8888888b. .d88888b. .d8888b.
888 Y88b d88P" "Y88b d88P Y88b
888 888 888 888 Y88b.
888 d88P 888 888 888 888 888 888 "Y888b.
8888888P" 888 888 `Y8bd8P' 888 888 "Y88b.
888 T88b 888 888 X88K 888 888 "888
888 T88b Y88b 888 .d8""8b. Y88b. .d88P Y88b d88P
888 T88b "Y88888 888 888 "Y88888P" "Y8888P"
arch = x86_64
platform = x86_64-qemu-q35
target = x86_64-unknown-none
smp = 1
build_mode = release
log_level = error
[ 0.131281 0 axfs_ramfs::dir:55] AlreadyExists sys
sqlite version: 3.41.1
sqlite open memory status 0
======== init user table ========
sqlite exec:
create table user(id INTEGER PRIMARY KEY AUTOINCREMENT,username TEXT,password TEXT)
======== insert user 1, 2, 3 into user table ========
sqlite exec:
insert into user (username, password) VALUES ('memory_1', 'password1'), ('memory_2', 'password2'), ('memory_3', 'password3')
======== select all ========
sqlite query:
select * from user
id = 1
username = memory_1
password = password1
id = 2
username = memory_2
password = password2
id = 3
username = memory_3
password = password3
======== select id = 2 ========
sqlite query:
select * from user where id = 2
id = 2
username = memory_2
password = password2
sqlite open /file.sqlite status 0
======== init user table ========
sqlite exec:
create table user(id INTEGER PRIMARY KEY AUTOINCREMENT,username TEXT,password TEXT)
======== insert user 1, 2, 3 into user table ========
sqlite exec:
insert into user (username, password) VALUES ('file_1', 'password1'), ('file_2', 'password2'), ('file_3', 'password3')
======== select all ========
sqlite query:
select * from user
id = 1
username = file_1
password = password1
id = 2
username = file_2
password = password2
id = 3
username = file_3
password = password3
======== select id = 2 ========
sqlite query:
select * from user where id = 2
id = 2
username = file_2
password = password2
再次运行上述命令，可得到如下运行结果：
SeaBIOS (version rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org)
iPXE (http://ipxe.org) 00:02.0 CA00 PCI2.10 PnP PMM+7EFD0AA0+7EF30AA0 CA00
Booting from ROM..
Initialize IDT & GDT...
8888888b. .d88888b. .d8888b.
888 Y88b d88P" "Y88b d88P Y88b
888 888 888 888 Y88b.
888 d88P 888 888 888 888 888 888 "Y888b.
8888888P" 888 888 `Y8bd8P' 888 888 "Y88b.
888 T88b 888 888 X88K 888 888 "888
888 T88b Y88b 888 .d8""8b. Y88b. .d88P Y88b d88P
888 T88b "Y88888 888 888 "Y88888P" "Y8888P"
arch = x86_64
platform = x86_64-qemu-q35
target = x86_64-unknown-none
smp = 1
build_mode = release
log_level = error
[ 0.130932 0 axfs_ramfs::dir:55] AlreadyExists sys
sqlite version: 3.41.1
sqlite open memory status 0
======== init user table ========
sqlite exec:
create table user(id INTEGER PRIMARY KEY AUTOINCREMENT,username TEXT,password TEXT)
======== insert user 1, 2, 3 into user table ========
sqlite exec:
insert into user (username, password) VALUES ('memory_1', 'password1'), ('memory_2', 'password2'), ('memory_3', 'password3')
======== select all ========
sqlite query:
select * from user
id = 1
username = memory_1
password = password1
id = 2
username = memory_2
password = password2
id = 3
username = memory_3
password = password3
======== select id = 2 ========
sqlite query:
select * from user where id = 2
id = 2
username = memory_2
password = password2
sqlite open /file.sqlite status 0
======== init user table ========
sqlite exec:
create table user(id INTEGER PRIMARY KEY AUTOINCREMENT,username TEXT,password TEXT)
sqlite exec error: table user already exists
======== insert user 1, 2, 3 into user table ========
sqlite exec:
insert into user (username, password) VALUES ('file_1', 'password1'), ('file_2', 'password2'), ('file_3', 'password3')
======== select all ========
sqlite query:
select * from user
id = 1
username = file_1
password = password1
id = 2
username = file_2
password = password2
id = 3
username = file_3
password = password3
id = 4
username = file_1
password = password1
id = 5
username = file_2
password = password2
id = 6
username = file_3
password = password3
======== select id = 2 ========
sqlite query:
select * from user where id = 2
id = 2
username = file_2
password = password2
出现差异的原因是第一次运行之后进行了数据持久化，再次运行时，上次存储的键值对仍然在块设备上。
如果运行下列命令，则数据不会进行持久化：
make A=apps/c/sqlite3/ LOG=error BLK=y run FEATURES=driver-ramdisk