Android下这样查数据库会比较酷

时间 2019-11-16

原文原文链接

sqlite你们不会陌生。Android原生数据库就是它了。开发过程当中咱们若是想临时查看数据库中的表结构或内容每每要大费周折的将数据库拷贝出来而后拿工具打开查看，每回都这样倒腾实在有些麻烦。android

实际上在Android Shell下已经有sqlite3环境了，而且足够知足基础的使用。咱们来看一下如何使用。sql

sqlite> .mode column
sqlite> select * from RoutingEntity;
id          current_num  max_num      time           warning_num  type    
----------  ----------  ----------  -------------  ----------  ----------
1           2           2           1518247150757  1           1         
2           2           2           1518247168420  1           1         
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此时会获得一张很漂亮的表结构信息。

也就是说，咱们若是须要获得这样的表结构，咱们依次须要输入

qlite3 xxx.db //打开数据库
.header on //启用表头
.mode column //使用列模式
select * from xxx //查询某张表

才能够获得漂亮的数据。吐槽一句，sqlite的这种设计有点愚蠢，为何不是一开始就默认启用表头和列模式呢？

花式输出

除了column模式之外，其实还内置了几组不一样的模式。分别是:

ascii
csv
column
html
insert
line
list
tabs
tcl

咱们试一下html模式

sqlite> .mode html
sqlite> select * from RoutingEntity;
<TR><TH>id</TH>
<TH>current_num</TH>
<TH>max_num</TH>
<TH>time</TH>
<TH>warning_num</TH>
<TH>type</TH>
</TR>
<TR><TD>1</TD>
<TD>2</TD>
<TD>2</TD>
<TD>1518247150757</TD>
<TD>1</TD>
<TD>1</TD>
</TR>
<TR><TD>2</TD>
<TD>2</TD>
<TD>2</TD>
<TD>1518247168420</TD>
<TD>1</TD>
<TD>1</TD>
</TR>

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哇哦，有点炸裂。

再来一组tcl。

sqlite> .mode tcl
sqlite> select * from RoutingEntity;
"id" "current_num" "max_num" "time" "warning_num" "type"
"1" "2" "2" "1518247150757" "1" "1"
"2" "2" "2" "1518247168420" "1" "1 复制代码

csv

sqlite> .mode csv
sqlite> select * from RoutingEntity;
id,current_num,max_num,time,warning_num,type
1,2,2,1518247150757,1,1
2,2,2,1518247168420,1,1
复制代码

帮助

若是咱们想知道更多的用法，可使用 .help来打开查看。

sqlite> .help
.backup ?DB? FILE      Backup DB (default "main") to FILE
.bail on|off           Stop after hitting an error.  Default OFF
.binary on|off         Turn binary output on or off.  Default OFF
.clone NEWDB           Clone data into NEWDB from the existing database
.databases             List names and files of attached databases
.dbinfo ?DB?           Show status information about the database
.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
.eqp on|off            Enable or disable automatic EXPLAIN QUERY PLAN
.exit                  Exit this program
.explain ?on|off?      Turn output mode suitable for EXPLAIN on or off.
                         With no args, it turns EXPLAIN on.
.fullschema            Show schema and the content of sqlite_stat tables
.headers on|off        Turn display of headers on or off
.help                  Show this message
.import FILE TABLE     Import data from FILE into TABLE
.indexes ?TABLE?       Show names of all indexes
                         If TABLE specified, only show indexes for tables
                         matching LIKE pattern TABLE.
.limit ?LIMIT? ?VAL?   Display or change the value of an SQLITE_LIMIT
.log FILE|off          Turn logging on or off.  FILE can be stderr/stdout
.mode MODE ?TABLE?     Set output mode where MODE is one of:
                         ascii    Columns/rows delimited by 0x1F and 0x1E
                         csv      Comma-separated values
                         column   Left-aligned columns.  (See .width)
                         html     HTML <table> code
                         insert   SQL insert statements for TABLE
                         line     One value per line
                         list     Values delimited by .separator strings
                         tabs     Tab-separated values
                         tcl      TCL list elements
.nullvalue STRING      Use STRING in place of NULL values
.once FILENAME         Output for the next SQL command only to FILENAME
.open ?FILENAME?       Close existing database and reopen FILENAME
.output ?FILENAME?     Send output to FILENAME or stdout
.print STRING...       Print literal STRING
.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
.save FILE             Write in-memory database into FILE
.scanstats on|off      Turn sqlite3_stmt_scanstatus() metrics on or off
.schema ?TABLE?        Show the CREATE statements
                         If TABLE specified, only show tables matching
                         LIKE pattern TABLE.
.separator COL ?ROW?   Change the column separator and optionally the row
                         separator for both the output mode and .import
.shell CMD ARGS...     Run CMD ARGS... in a system shell
.show                  Show the current values for various settings
.stats on|off          Turn stats on or off
.system CMD ARGS...    Run CMD ARGS... in a system shell
.tables ?TABLE?        List names of tables
                         If TABLE specified, only list tables matching
                         LIKE pattern TABLE.
.timeout MS            Try opening locked tables for MS milliseconds
.timer on|off          Turn SQL timer on or off
.trace FILE|off        Output each SQL statement as it is run
.vfsname ?AUX?         Print the name of the VFS stack
.width NUM1 NUM2 ...   Set column widths for "column" mode
                         Negative values right-justify
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Android下这样查数据库会比较酷

目录

数据库文件路径

查看表名称

使用sql查询

格式化

花式输出

帮助