文章参照：www.sqlite.org/sqlite.html
在sqlite3中我们可以通过".help"命令来查所有的非SQL命令。
比如，示例4：
sqlite> .help
.help
.backup DB FILE Backup DB (default "main") to FILE
.bail ON|OFF Stop after hitting an error. Default OFF
.databases List names and files of attached databases
.dump TABLE ... Dump the database in an SQL text format
If TABLE specified, only dump tables matching
LIKE pattern TABLE.
.echo ON|OFF Turn command echo on or off
.exit Exit this program
.explain ON|OFF Turn output mode suitable for EXPLAIN on or off.
With no args, it turns EXPLAIN on.
.genfkey OPTIONS Options are:
--no-drop: Do not drop old fkey triggers.
--ignore-errors: Ignore tables with fkey errors
--exec: Execute generated SQL immediately
See file tool/genfkey.README in the source
distribution for further information.
.header(s) ON|OFF Turn display of headers on or off
.help Show this message
.import FILE TABLE Import data from FILE into TABLE
.indices TABLE Show names of all indices
If TABLE specified, only show indices for tables
matching LIKE pattern TABLE.
.load FILE ENTRY Load an extension library
.log FILE|off Turn logging on or off. FILE can be stderr/stdout
.mode MODE TABLE Set output mode where MODE is one of:
csv Comma-separated values
column Left-aligned columns. (See .width)
html HTML
code
insert SQL insert statements for TABLE
line One value per line
list Values delimited by .separator string
tabs Tab-separated values
tcl TCL list elements
.nullvalue STRING Print STRING in place of NULL values
.output FILENAME Send output to FILENAME
.output stdout Send output to the screen
.prompt MAIN CONTINUE Replace the standard prompts
.quit Exit this program
.read FILENAME Execute SQL in FILENAME
.restore DB FILE Restore content of DB (default "main") from FILE
.schema TABLE Show the CREATE statements
If TABLE specified, only show tables matching
LIKE pattern TABLE.
.separator STRING Change separator used by output mode and .import
.show Show the current values for various settings
.tables TABLE List names of tables
If TABLE specified, only list tables matching
LIKE pattern TABLE.
.timeou