【转载】Using SQLite from Shell in Android（在shell 下使用sqlite命令操作数据库）

This article looks at using SQLite from the Android shell.

 

Table of Contents

Where is SQLite?

Code Listing 1. Contents of system/bin

Where are the SQLite databases on an Android Device?

Code Listing 2. The location of the notepad database

Code Listing 3. The /data/data directory

Starting the SQLite command line program

Starting generically

Code Listing 4. The SQLite commands available from the command line utility

Opening a database

Code Listing 5. Opening a specific database from SQLite command line

Example Commands from the SQLite command line program

Getting the list of tables

Code Listing 6. List of tables

Getting the schema of the tables

Code Listing 7. Schema of tables

SQL Queries

Figure 1. Notes in the Note pad application

Code Listing 8. Data from notes

Code Listing 9. Creation of the notes table

Related Articles

 

Where is SQLite?

SQLite is available on the Android device itself. The executable is in the /system/bin directory of the device. You can see that this directory contains the shell commands like ls, ps, etc., as well as sqlite3, dalvikvm, and dexdump utilities.

Code Listing 1. Contents of system/bin

# pwd 
pwd 
/system/bin 

# ls -l 
ls -l 
-rwxr-xr-x root root 196 2008-02-29 01:09 am 
-rwxr-xr-x root root 2342 2008-02-29 01:09 dumpstate 
-rwxr-xr-x root root 208 2008-02-29 01:09 input 
-rwxr-xr-x root root 212 2008-02-29 01:09 monkey 
-rwxr-xr-x root root 196 2008-02-29 01:09 pm 

… 

lrwxr-xr-x root root 2008-02-29 01:16 mount -> toolbox 
lrwxr-xr-x root root 2008-02-29 01:16 notify -> toolbox 
-rwxr-xr-x root root 28032 2008-02-29 01:16 dexdump 
-rwxr-xr-x root root 7100 2008-02-29 01:16 dumpsys 
-rwxr-xr-x root root 7904 2008-02-29 01:16 mem_profiler 
-rwxr-xr-x root root 6480 2008-02-29 01:16 service 
-rwxr-xr-x root root 4320 2008-02-29 01:16 rild 
-rwxr-xr-x root root 4928 2008-02-29 01:16 sdutil 
-rwxr-xr-x root root 26488 2008-02-29 01:16 sqlite3 
-rwxr-xr-x root root 4148 2008-02-29 01:16 dexopt 
-rwxr-xr-x root root 4908 2008-02-29 01:16 dalvikvm 
-rwsr-sr-x root root 3200 2008-02-29 01:16 surfaceflinger 
-rwxr-xr-x root root 5420 2008-02-29 01:16 app_process 
-rwxr-xr-x root root 39408 2008-02-29 01:16 runtime 
-rwxr-xr-x root root 2920 2008-02-29 01:16 system_server 
-rwxr-xr-x root root 9168 2008-02-29 01:17 pv 

Where are the SQLite databases on an Android Device?

By default, the SQLite databases have an extension .db. For example, a NotePad application may use note_pad.db database. This might be created from code using Android SDK’s SQLite classes/methods. By default, the SQLite database for an application is in the /data/data/<app>/databases directory. As you can see from the listing below, the notepad database is in the /data/data/com.google.android.notepad/databases directory.

Code Listing 2. The location of the notepad database

# pwd 
pwd 
/data/data/com.google.android.notepad/databases 

# ls -l 
ls -l 
-rw-rw---- app_8 app_8 3072 2008-03-18 18:23 note_pad.db 

You can see a whole bunch of these sub-directories under the /data/data directory.

Code Listing 3. The /data/data directory

# pwd 
pwd 
/data/data 

# ls 
ls 
com.google.android.notepad 
com.google.android.samples 
com.google.android.gtalkservice 
com.google.android.phone 
com.google.android.maps 
com.google.android.providers.im 
com.google.android.home 
com.google.android.googleapps 
com.google.android.gtalksettings 
com.google.android.fallback 
com.google.android.development 
com.google.android.contacts 
com.google.android.browser 
com.google.android.providers.telephony 
com.google.android.providers.settings 
com.google.android.providers.media 
com.google.android.masfproxyservice 
com.google.android.providers.googleapps 
com.google.android.providers.contacts 
android 

Starting the SQLite command line program

Starting generically

Typing sqlite3 in the Android Shell will open the SQLite command line program (since sqlite3 is in the /system/bin directory). Typing .help gives the summarized set of commands available from here.

Code Listing 4. The SQLite commands available from the command line utility

# sqlite3 
sqlite3 
SQLite version 3.5.0 
Enter ".help" for instructions 

sqlite> .help 
.help 
.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 
.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. 
.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 on TABLE 
.load FILE ?ENTRY? Load an extension library 
.mode MODE ?TABLE? Set output mode where MODE is one of: 
                         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 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 
.schema ?TABLE? Show the CREATE statements 
.separator STRING Change separator used by output mode and .import 
.show Show the current values for various settings 
.tables ?PATTERN? List names of tables matching a LIKE pattern 
.timeout MS Try opening locked tables for MS milliseconds 
.width NUM NUM ... Set column widths for "column" mode 
sqlite> 

Opening a database

You would, of course, want to see the data and structure of a particular database. In the listing below, the note_pad.db is opened for further querying. Here, I went to the directory where the database is; however, you can also specify the full path.

Code Listing 5. Opening a specific database from SQLite command line

# pwd 
pwd 
/data/data/com.google.android.notepad/databases 

# ls 
ls 
note_pad.db 

# sqlite3 note_pad.db 
sqlite3 note_pad.db 
SQLite version 3.5.0 
Enter ".help" for instructions 
sqlite> 

Example Commands from the SQLite command line program

Getting the list of tables

You can get the list of all the tables in the current database in two ways: from the .tables command or by querying the sqlite_master table.

Code Listing 6. List of tables

sqlite> .tables 
.tables 
android_metadata notes 

sqlite> select * from sqlite_master; 
select * from sqlite_master; 
table|android_metadata|android_metadata|2|CREATE TABLE android_metadata (locale 
TEXT) 
table|notes|notes|3|CREATE TABLE notes (_id INTEGER PRIMARY KEY,title TEXT,note 
TEXT,created INTEGER,modified INTEGER) 

Getting the schema of the tables

By using the .schema command, you can get the schema of either all of the tables or a single table.

Code Listing 7. Schema of tables

sqlite> .schema 
.schema 
CREATE TABLE android_metadata (locale TEXT); 
CREATE TABLE notes (_id INTEGER PRIMARY KEY,title TEXT,note TEXT,created INTEGER 
,modified INTEGER); 

sqlite> .schema notes 
.schema notes 
CREATE TABLE notes (_id INTEGER PRIMARY KEY,title TEXT,note TEXT,created INTEGER 
,modified INTEGER); 

SQL Queries

You can issue queries like ‘select * from notes’ to get the data from the notes table. As you can see from the figure below, I have entered a series of notes in the notepad application.

Figure 1. Notes in the Note pad application

After entering the notes, if you query the notes table, you will get the data in the _id, title, note, created, and modified columns.

Code Listing 8. Data from notes

sqlite> .schema notes 
.schema notes 
CREATE TABLE notes (_id INTEGER PRIMARY KEY,title TEXT,note TEXT,created INTEGER 
,modified INTEGER); 

sqlite> select * from notes; 
select * from notes; 
1|Title of Note 
This is a test note.|This is a test note.|1205871448827|1205873944838 
3|Another note 
Some text.|A third note 
Some text.|1205873990394|1205874145996 
4|One more 
Body here|One more 
Body here|1205874074992|1205874088072 

And, finally, we can take a look at how this table was created.

Code Listing 9. Creation of the notes table

public class NotePadProvider extends ContentProvider { 

… 

    private static class DatabaseHelper extends SQLiteOpenHelper { 

        @Override 
        public void onCreate(SQLiteDatabase db) { 
            db.execSQL("CREATE TABLE notes (_id INTEGER PRIMARY KEY," 
                    + "title TEXT," + "note TEXT," + "created INTEGER," 
                    + "modified INTEGER" + ");"); 
        } 
… 

    } 

… 

    @Override 
    public boolean onCreate() { 
        DatabaseHelper dbHelper = new DatabaseHelper(); 
        mDB = dbHelper.openDatabase(getContext(), DATABASE_NAME, null, DATABASE_VERSION); 
        return (mDB == null) ? false : true; 
    } 

… 

} 

As you can see above, CREATE TABLE sql has been used to create the notes table. Classes like SQLiteOpenHelper and ContentProvider from Android SDK are put to use here.

PS：原文地址http://www.infinitezest.com/articles/using-sqlite-from-shell-in-android.aspx