Sqlite3

Overview

Sqlite3 사용법 정리.

Commands

원문은 이곳<ref>https://www.sqlite.org/cli.html</ref>을 참조하자.

sqlite> .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.
.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 <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      Use STRING in place of NULL values
.open ?FILENAME?       Close existing database and reopen FILENAME
.output FILENAME       Send output to FILENAME
.output stdout         Send output to the screen
.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
.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
.stats ON|OFF          Turn stats on or off
.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
.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
.timer ON|OFF          Turn the CPU timer measurement on or off

.tables

현재의 데이터베이스에 있는 테이블 내용을 보여준다. 특정 테이블 이름을 같이 입력할 경우, 입력한 테이블이 데이터베이스에 존재하는지를 리턴한다.

sqlite> .tables
sample1  test   
sqlite> .tables test
test
sqlite> .tables test1
sqlite> 

.schema

입력한 테이블의 상세 내용을 확인한다. 만약, 입력한 테이블 내용이 없을 경우, 해당 데이터베이스의 전체 테이블의 상세 내용을 출력한다.

sqlite> .schema test
CREATE TABLE test(seq integer PRIMARY KEY AUTOINCREMENT, test text);

sqlite> .schema
CREATE TABLE test(seq integer PRIMARY KEY AUTOINCREMENT, test text);
CREATE TABLE sample1(seq integer);

Datatypes

Strong classes and datatypes

Sqlite 에서는 크게 다음과 같은 분류로 데이터타입을 정의한다.

    NULL. The value is a NULL value.

    INTEGER. The value is a signed integer, stored in 1, 2, 3, 4, 6, or 8 bytes depending on the magnitude of the value.

    REAL. The value is a floating point value, stored as an 8-byte IEEE floating point number.

    TEXT. The value is a text string, stored using the database encoding (UTF-8, UTF-16BE or UTF-16LE).

    BLOB. The value is a blob of data, stored exactly as it was input.

Boolean Datatype

SQLite 에는 Boolean 타입을 위한 데이터 타입이 없다. 대신, integer 0(false), integer 1(true) 로 저장된다.

Date and Time Datatype

SQLite does not have a storage class set aside for storing dates and/or times. Instead, the built-in Date And Time Functions of SQLite are capable of storing dates and times as TEXT, REAL, or INTEGER values:

   TEXT as ISO8601 strings ("YYYY-MM-DD HH:MM:SS.SSS").
   REAL as Julian day numbers, the number of days since noon in Greenwich on November 24, 4714 B.C. according to the proleptic Gregorian calendar.
   INTEGER as Unix Time, the number of seconds since 1970-01-01 00:00:00 UTC.

Pragma

table_info()

입력된 table 의 정보를 출력한다. 각각의 라인마다 테이블에 있는 모든 칼럼과 속성을 하나씩 출력한다. table 뿐만 아니라 view 정보도 확인할 수 있다. 각각의 항목별 내용은 아래 순서와 같다.

• Index
• Column name
• Data type
• Set NULL 가능 여부.(0:가능, 1:불가능)
• Default value
• Primary key 여부

sqlite> pragma table_info(test);
0|seq|integer|0||1
1|uniq_id|text|1||0

Example

Database 생성 후, 샘플 데이터를 입력한 뒤, 이를 프로그램을 통해 출력하는 예제를 작성해보자.

database 생성

$ sqlite3 test.db

sqlite> create table t1(
   ...> id int 
   ...> id int primary key not null,
   ...> name text not null,
   ...> age int not null,
   ...> address char(50),
   ...> salary real
   ...> );
sqlite> .table
t1

sqlite> .schema t1
CREATE TABLE t1(
id int primary key not null,
name text not null,
age int not null,
address char(50),
salary real
);

sqlite> insert into t1 (id, name, age, address, salary) values (1, "test_1", 10, "Somewhere in the earth", 10000);
sqlite> select * from t1;
1|test_1|10|Somewhere in the earth|10000.0

샘플 프로그램

<source lang=c> /*

* main.c
* 
* Copyright 2015 sungtae kim <pchero@mywork>
* 
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
* 
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
* GNU General Public License for more details.
* 
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
* MA 02110-1301, USA.
* 
* 
*/

1. include <stdio.h>
2. include <sqlite3.h>

static int callback(void *NotUsed, int argc, char **argv, char **azColName) { int i; for(i = 0; i < argc; i++) { printf("%s = %s\n", azColName[i], argv[i] ? argv[i] : "NULL"); }

printf("\n"); return 0; }

int main(int argc, char **argv) { sqlite3 *db; char *zErrMsg = 0; int rc;

if(argc != 3) { fprintf(stderr, "Usage: %s DATABASE SQL-STATEMENT\n", argv[0]); return 1; } rc = sqlite3_open(argv[1], &db); if(rc) { fprintf(stderr, "Can't open database: %s\n", sqlite3_errmsg(db)); sqlite3_close(db); return(1); }

rc = sqlite3_exec(db, argv[2], callback, 0, &zErrMsg); if(rc != SQLITE_OK) { fprintf(stderr, "SQL_error: %s\n", zErrMsg); sqlite3_free(zErrMsg); } sqlite3_close(db); return 0; } </source>

$ gcc -o main main.c -lsqlite3

$ ./main test.db "select * from t1"
id = 1
name = test_1
age = 10
address = Somewhere in the earth
salary = 10000.0

See also

• https://www.sqlite.org/datatype3.html - Datatypes In SQLite Version 3
• https://www.sqlite.org/pragma.html - PRAGMA Statements

References

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