SQLite3 笔记
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SQLite insert 插入一行： 插入一组： 使用select结果插入 多行插入到新表： 多行插入到新表，一步到位： 非常有用的临时表： sqlite update 更新一条记录： update 注意 约束 sqlite delete 约束： 唯一约束unique autoincrement 主键约束 域约束：默认值 时间戳默认值 NOT NULL 约束 check 约束 check 约束 复杂 外键约束 SQLite 存储类 视图 索引 触发器 视图触发器：可更新的视图 事务 冲突
SQLite insert
查看表结构：
sqlite> .schema foods CREATE TABLE foods( id integer primary key, type_id integer, name text );
插入一行：
sqlite> insert into foods (name,type_id) values(‘Cinnamon Bobka‘, 1); sqlite> insert into foods values(NULL, 1, ‘Blueberry Bobka‘); 验证： sqlite> select * from foods where name like ‘%bobka‘; id type_id name ---------- ---------- --------------- 10 1 Chocolate Bobka 13 1 Cinnamon Bobka 413 1 Cinnamon Bobka 414 1 Blueberry Bobka
插入一组：
sqlite> insert into foods values(null, (select id from food_types where name=‘Bakery‘), ‘Blackberry Bobka‘); sqlite> select * from foods where name like ‘%bobka‘; id type_id name ---------- ---------- --------------- 10 1 Chocolate Bobka 13 1 Cinnamon Bobka 413 1 Cinnamon Bobka 414 1 Blueberry Bobka 415 1 Blackberry Bobk sqlite>
使用select结果插入
sqlite> insert into foods ...> select last_insert_rowid()+1, type_id, name from foods where name =‘Chocolate Bobka‘; sqlite> select * from foods where name like ‘%bobka‘; id type_id name ---------- ---------- --------------- 10 1 Chocolate Bobka 13 1 Cinnamon Bobka 413 1 Cinnamon Bobka 414 1 Blueberry Bobka 415 1 Blackberry Bobk 416 1 Chocolate Bobka sqlite> [注意]：字段个数要匹配，数据类型也要匹配： 否则，失败。 sqlite> .schema foods CREATE TABLE foods( id integer primary key, type_id integer, name text ); sqlite> insert into foods select last_insert_rowid()+100, name, type_id from foods where name =‘Chocolate Bobka‘; Error: UNIQUE constraint failed: foods.id sqlite>
多行插入到新表：
sqlite> create table foods2 (id int, type_id int, name text); sqlite> insert into foods2 select * from foods; sqlite> select count(*) from foods2; count(*) ---------- 416 sqlite>
多行插入到新表，一步到位：
sqlite> create table foods3 as select * from foods; sqlite> select count(*) from foods3; count(*) ---------- 416 sqlite>
非常有用的临时表：
sqlite> create temp table list as select f.name food, t.name name, (select count(episode_id) from foods_episodes where food_id=f.id) episodes from foods f, food_types t where f.type_id = t.id; sqlite> select * from list; food name episodes ---------- ---------- ---------- Bagels Bakery 1 Bagels, ra Bakery 2 Bavarian C Bakery 1 Bear Claws Bakery 3 Black and Bakery 2 Bread (wit Bakery 1 Butterfing Bakery 1 Carrot Cak Bakery 1 Chips Ahoy Bakery 1
使用 create table 的这种形式，自增长字段在新表中创建，索引也不会创建，UNIOUE约束都不会被创建。
插入行时的 unique 约束，如果在定义为 unique 的字段中插入重复值，SQLite 会停止并报错。
sqlite> insert into foods values (416, 1, ‘Chocolate Bobka‘); Error: UNIQUE constraint failed: foods.id sqlite>
sqlite update
更新一条记录：
sqlite> update foods set name=‘CHOCOLATE BOBKA‘ where name=‘Chocolate Bobka‘; sqlite> select * from foods where name like ‘CHOCOLATE%‘; id type_id name ---------- ---------- --------------- 10 1 CHOCOLATE BOBKA 11 1 Chocolate Eclai 12 1 Chocolate Cream 222 9 Chocolates, box 223 9 Chocolate Chip 224 9 Chocolate Cover 416 1 CHOCOLATE BOBKA sqlite>
update 注意 约束
sqlite> .schema foods CREATE TABLE foods( id integer primary key, type_id integer, name text ); sqlite> sqlite> update foods set id=11 where name=‘CHOCOLATE BOBKA‘; Error: UNIQUE constraint failed: foods.id sqlite>
sqlite delete
sqlite> delete from foods where name=‘CHOCOLATE BOBKA‘;
约束：
唯一约束unique
create table contacts ( int integer primary key, name text not null collate nocase, phone text not null default ‘UNKNOWN‘, unique (name, phone) ); insert into contacts (name, phone) values (‘Jerry‘, ‘UNKNOWN‘);
autoincrement
autoincrement 并不会使用未被使用的数字，而是自动递增，但不会阻挡你自己提供的值
sqlite> create table maxed_out(id integer primary key autoincrement, x text); sqlite> insert into maxed_out values(10,‘wors‘); sqlite> select * from maxed_out; id x ---------- ---------- 10 wors sqlite> insert into maxed_out values (9223372036854775807,‘last one‘); sqlite> select * from maxed_out; id x ---------- ---------- 10 wors 9223372036 last one sqlite> insert into maxed_out values (NULL,‘will not work‘); Error: database or disk is full sqlite>
主键约束
约束：主键约束 primary key 不允许存在同样的 sqlite> create table pkey(x text, y text, primary key(x,y)); sqlite> insert into pkey values (‘x‘,‘y‘); sqlite> insert into pkey values (‘x‘,‘x‘); sqlite> select rowid, x, y from pkey; rowid x y ---------- ---------- ---------- 1 x y 2 x x sqlite> insert into pkey values (‘x‘,‘x‘); Error: UNIQUE constraint failed: pkey.x, pkey.y sqlite>
域约束：默认值
域约束：默认值，NULL， NOT NULL ，check，sort 1, default 默认值 create table contacts ( int integer primary key, name text not null collate nocase, phone text not null default ‘UNKNOWN‘, unique (name, phone) ); sqlite> insert into contacts (name) values (‘Tom‘); sqlite> select * from contacts; int name phone ---------- ---------- ---------- 1 Jerry UNKNOWN 2 Jerry 021-110 3 Tom UNKNOWN sqlite>
时间戳默认值
create table times ( id int, date not null default current_date, time not null default current_time, timestamp not null default current_timestamp); sqlite> insert into times (id) values (1); sqlite> insert into times (id) values (2); sqlite> select * from times; id date time timestamp ---------- ---------- ---------- ------------------- 1 2017-02-10 06:14:30 2017-02-10 06:14:30 2 2017-02-10 06:14:32 2017-02-10 06:14:32 sqlite>
NOT NULL 约束
sqlite> .schema contacts
CREATE TABLE contacts (
int integer primary key,
name text not null collate nocase,
phone text not null default ‘UNKNOWN‘,
unique (name, phone)
);
sqlite> insert into contacts (phone) values ("134-1234-5678");
Error: NOT NULL constraint failed: contacts.name
sqlite>check 约束
create table contacts ( id integer primary key, name text not null collate nocase, phone text not null default ‘空号‘, unique (name,phone), check (length(phone)>=7) );
check 约束 复杂
check 约束 复杂 create table foo ( x integer, y integer check(y>x), z integer check (z>abs(y)) ); sqlite> insert into foo values (-2, -1, 2); sqlite> select * from foo; x y z ---------- ---------- ---------- -2 -1 2 sqlite> update foo set z=-3 where z=2; Error: CHECK constraint failed: foo sqlite>
外键约束
外键约束 http://www.sqlite.org/foreignkeys.html 确保foods的type_id 已存在于food_types的id中。 CREATE TABLE food_types( id integer primary key, name text ); CREATE TABLE foods( id integer primary key, type_id integer references food_types(id) on delete restrict deferrable initially deferred, name text ); NO ACTION: Configuring "NO ACTION" means just that: when a parent key is modified or deleted from the database, no special action is taken. RESTRICT: The "RESTRICT" action means that the application is prohibited from deleting (for ON DELETE RESTRICT) or modifying (for ON UPDATE RESTRICT) a parent key when there exists one or more child keys mapped to it. The difference between the effect of a RESTRICT action and normal foreign key constraint enforcement is that the RESTRICT action processing happens as soon as the field is updated - not at the end of the current statement as it would with an immediate constraint, or at the end of the current transaction as it would with a deferred constraint. Even if the foreign key constraint it is attached to is deferred, configuring a RESTRICT action causes SQLite to return an error immediately if a parent key with dependent child keys is deleted or modified. SET NULL: If the configured action is "SET NULL", then when a parent key is deleted (for ON DELETE SET NULL) or modified (for ON UPDATE SET NULL), the child key columns of all rows in the child table that mapped to the parent key are set to contain SQL NULL values. SET DEFAULT: The "SET DEFAULT" actions are similar to "SET NULL", except that each of the child key columns is set to contain the columns default value instead of NULL. Refer to the CREATE TABLE documentation for details on how default values are assigned to table columns. CASCADE: A "CASCADE" action propagates the delete or update operation on the parent key to each dependent child key. For an "ON DELETE CASCADE" action, this means that each row in the child table that was associated with the deleted parent row is also deleted. For an "ON UPDATE CASCADE" action, it means that the values stored in each dependent child key are modified to match the new parent key values.
4,排序
create table contacts ( int integer primary key, name text not null collate nocase, phone text not null default ‘UNKNOWN‘, unique (name, phone) ); collate 定义排序规则： nocase 忽略大小写 组合起来就是：‘Jerry‘与‘jerry‘在插入的时候会被忽略大小写，然后就是一样的，无法二次插入
SQLite
存储类
存储类 描述 NULL 值是一个 NULL 值。 INTEGER 值是一个带符号的整数，根据值的大小存储在 1、2、3、4、6 或 8 字节中。 REAL 值是一个浮点值，存储为 8 字节的 IEEE 浮点数字。 TEXT 值是一个文本字符串，使用数据库编码（UTF-8、UTF-16BE 或 UTF-16LE）存储。 BLOB 值是一个 blob 数据，完全根据它的输入存储。
视图
视图即虚拟表，也称为派生表。因为视图的内容来自其他的查询结果。 视图不是基本表，尽管感觉起来与表是一样的。基本表的内容是持久的，视图是动态产生的。 视图的起源：如果需要频繁查此表 select f.name, ft.name, e.name from foods f inner join food_types ft on f.type_id=ft.id inner join foods_episodes fe on f.id=fe.food_id inner join episodes e on fe.episode_id=e.id; 创建视图：SQLite不支持可更新的视图 create view details as select f.name as fd, ft.name as tp, e.name as ep, e.season as ssn from foods f inner join food_types ft on f.type_id=ft.id inner join foods_episodes fe on f.id=fe.food_id inner join episodes e on fe.episode_id=e.id; sqlite> select * from details limit 10; fd tp ep ssn ---------- ---------- ---------- ---------- Bagels Bakery The Strike 9 Bagels, ra Bakery The Strike 9 Bagels, ra Bakery The Muffin 8 Bavarian C Bakery The Soup N 7 Bear Claws Bakery The Strong 9 Bear Claws Bakery The Sniffi 5 Bear Claws Bakery The Rainco 5 Black and Bakery The Dinner 5 Black and Bakery The Unders 6 Bread (wit Bakery The Apolog 9 sqlite> 删除视图： drop view details;
索引
索引： 索引是一种用来在某种条件下加速查询的结构。 创建唯一索引 sqlite> drop table foo; sqlite> create table foo(id integer,name text); sqlite> create unique index foo_index on foo(id,name); sqlite> insert into foo(id,name) values(250,‘老王‘); sqlite> insert into foo(id,name) values(11,‘张三‘); sqlite> insert into foo(id,name) values(250,‘老王‘); Error: UNIQUE constraint failed: foo.id, foo.name sqlite> select * from foo; id name ---------- ---------- 250 老王 11 张三 sqlite> 删除索引： sqlite> drop index foo_index;
创建大小写不敏感索引
sqlite> create index foods_name_idx on foods (name collate nocase); sqlite> .indices foods_name_idx sqlite> .schema foods CREATE TABLE foods( id integer primary key, type_id integer, name text ); CREATE INDEX foods_name_idx on foods (name collate nocase); sqlite>
触发器
当具体的表发生特定的数据库事件时，触发器执行对应的SQL命令 未更新的行用old引用，已更新的行用new引用 所有属性都可以用点来引用 create temp table log(x); create temp trigger foods_update_log update of name on foods begin insert into log values(‘update foods:new name=‘||new.name); end; begin; update foods set name=‘JUJYFRUIT‘ where name=‘JujyFruit‘; select * from log; rollback; 执行结果： sqlite> create temp table log(x); sqlite> create temp trigger foods_update_log update of name on foods ...> begin ...> insert into log values(‘update foods:new name=‘||new.name); ...> end; sqlite> sqlite> begin; sqlite> update foods set name=‘JUJYFRUIT‘ where name=‘JujyFruit‘; sqlite> select * from log; x ------------------------------- update foods:new name=JUJYFRUIT sqlite> rollback; sqlite> shell执行结果： [email protected]:~/work/sqlite$ cat trigger.sql create temp table log(x); create temp trigger foods_update_log update of name on foods begin insert into log values(‘update foods:new name=‘||new.name); end; begin; update foods set name=‘JUJYFRUIT‘ where name=‘JujyFruit‘; select * from log; rollback; [email protected]:~/work/sqlite$ sqlite3 foods.db < trigger.sql update foods:new name=JUJYFRUIT [email protected]:~/work/sqlite$
视图触发器：可更新的视图
[email protected]:~/work/sqlite$ cat trigger.sql --创建视图 create view foods_view as select f.id fid, f.name fname, t.id tid, t.name tname from foods f, food_types t; --创建触发器 create trigger on_update_foods_view instead of update on foods_view for each row begin update foods set name=new.fname where id=new.fid; update food_types set name=new.tname where id=new.tid; end; --小实验,更新视图的数据，自动同步到基础表 begin; update foods_view set fname=‘乐事薯片‘, tname=‘Fast Food‘ where fid=413; --查询底层表 select * from foods f, food_types t where f.type_id=t.id and f.id=413; rollback; --查询底层表 select * from foods f, food_types t where f.type_id=t.id and f.id=413; drop view foods_view; [email protected]:~/work/sqlite$ sqlite3 foods.db < trigger.sql 413|1|乐事薯片|1|Fast Food 413|1|Whataburger|1|Fast Food [email protected]:~/work/sqlite$
事务
SQLite事务： BEGIN [point] / COMMIT[point]/ROLLBACK[point] 默认情况下：SQLite事务是自动提交，执行成功则提交，执行失败则回滚。 begin 事务开始，之后的所有事务都可以取消 commit 提交 rollback 事务回滚 sqlite> begin; sqlite> delete from foods; sqlite> select count(*) from foods; 0 sqlite> rollback; sqlite> select count(*) from foods; 414 sqlite> ======================================================= 回滚到事务点： sqlite> begin; sqlite> select count(*) from foods; 414 sqlite> delete from foods; sqlite> select count(*) from foods; 0 sqlite> savepoint point1; sqlite> select count(*) from food_types; 15 sqlite> delete from food_types; sqlite> select count(*) from food_types; 0 sqlite> rollback to point1; sqlite> select count(*) from food_types; 15 sqlite> rollback; sqlite> select count(*) from foods; 414 sqlite>
冲突
冲突解决： SQLite提供5种冲突解决方案： replace 违反的记录被删除，以新记录代替之 ignore 违反的记录保持原貌，其它记录继续执行 fail 终止命令，违反之前执行的操作得到保存 abort 终止命令，恢复违反之前执行的修改 rollback终止命令和事务，回滚整个事务 语法： 语句级（可覆盖对象级的冲突解决手段） insert/update/create or [resolution] table/index [tbl_name/idx_name] …… [resolution]： replace、ignore、fail、abort、rollback 对象级（定义表格时） create table/index [tbl_name/idx_name] ([field_name] [format] [constraint] on conflict [resolution]); [constraint]：unique、not null…… sqlite> update foods set id=800-id; Error: UNIQUE constraint failed: foods.id sqlite> update or abort foods set id=800-id; Error: UNIQUE constraint failed: foods.id sqlite> update or replace foods set id=800-id; sqlite>
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