语法

    SQLite 是遵循一套独特的称为语法的规则和准则。本教程列出了所有基本的 SQLite 语法，向您提供了一个 SQLite 快速入门。

    有个重要的点值得注意，SQLite 是不区分大小写的，但也有一些命令是大小写敏感的，比如 GLOB 和 glob 在 SQLite 的语句中有不同的含义。

    SQLite 注释是附加的注释，可以在 SQLite 代码中添加注释以增加其可读性，他们可以出现在任何空白处，包括在表达式内和其他 SQL 语句的中间，但它们不能嵌套。

    SQL 注释以两个连续的 "-" 字符（ASCII 0x2d）开始，并扩展至下一个换行符（ASCII 0x0a）或直到输入结束，以先到者为准。

    您也可以使用 C 风格的注释，以 "/*" 开始，并扩展至下一个 "*/" 字符对或直到输入结束，以先到者为准。SQLite的注释可以跨越多行。

    sqlite>.help -- 这是一个简单的注释

    所有的 SQLite 语句可以以任何关键字开始，如 SELECT、INSERT、UPDATE、DELETE、ALTER、DROP 等，所有的语句以分号 ; 结束。

    SQLite ANALYZE 语句

    ANALYZE;
or
ANALYZE database_name;
or
ANALYZE database_name.table_name;

    SQLite AND/OR 子句

    SELECT column1, column2....columnN
FROM   table_name
WHERE  CONDITION-1 {AND|OR} CONDITION-2;

    SQLite ALTER TABLE 语句

    ALTER TABLE table_name ADD COLUMN column_def...;

    SQLite ALTER TABLE 语句（Rename）

    ALTER TABLE table_name RENAME TO new_table_name;

    SQLite ATTACH DATABASE 语句

    ATTACH DATABASE 'DatabaseName' As 'Alias-Name';

    SQLite BEGIN TRANSACTION 语句

    BEGIN;
or
BEGIN EXCLUSIVE TRANSACTION;

    SQLite BETWEEN 子句

    SELECT column1, column2....columnN
FROM   table_name
WHERE  column_name BETWEEN val-1 AND val-2;

    表示大于等于 val-1 小于等于 val-2

    SQLite COMMIT 语句

    COMMIT;

    SQLite CREATE INDEX 语句

    CREATE INDEX index_name
ON table_name ( column_name COLLATE NOCASE );

    SQLite CREATE UNIQUE INDEX 语句

    CREATE UNIQUE INDEX index_name
ON table_name ( column1, column2,...columnN);

    SQLite CREATE TABLE 语句

    CREATE TABLE table_name(
   column1 datatype,
   column2 datatype,
   column3 datatype,
   .....
   columnN datatype,
   PRIMARY KEY( one or more columns )
);

    SQLite CREATE TRIGGER 语句

    CREATE TRIGGER database_name.trigger_name 
BEFORE INSERT ON table_name FOR EACH ROW
BEGIN 
   stmt1; 
   stmt2;
   ....
END;

    SQLite CREATE VIEW 语句

    CREATE VIEW database_name.view_name  AS
SELECT statement....;

    SQLite CREATE VIRTUAL TABLE 语句

    CREATE VIRTUAL TABLE database_name.table_name USING weblog( access.log );
or
CREATE VIRTUAL TABLE database_name.table_name USING fts3( );

    SQLite COMMIT TRANSACTION 语句

    COMMIT;

    SQLite COUNT 子句

    SELECT COUNT(column_name)
FROM   table_name
WHERE  CONDITION;

    SQLite DELETE 语句

    DELETE FROM table_name
WHERE  {CONDITION};

    SQLite DETACH DATABASE 语句

    DETACH DATABASE 'Alias-Name';

    SQLite DISTINCT 子句

    SELECT DISTINCT column1, column2....columnN
FROM   table_name;

    SQLite DROP INDEX 语句

    DROP INDEX database_name.index_name;

    SQLite DROP TABLE 语句

    DROP TABLE database_name.table_name;

    SQLite DROP VIEW 语句

    DROP VIEW view_name;

    SQLite DROP TRIGGER 语句

    DROP TRIGGER trigger_name

    SQLite EXISTS 子句

    如果主查询的记录数大于子查询的记录数，用 in 效率高。
    如果主查询的记录数小于子查询的记录数，用 exists 效率高。

    SELECT column1, column2....columnN
FROM   table_name
WHERE  column_name EXISTS (SELECT * FROM   table_name );

    SQLite EXPLAIN 语句

    EXPLAIN INSERT statement...;
or 
EXPLAIN QUERY PLAN SELECT statement...;

    SQLite GLOB 子句

    SELECT column1, column2....columnN
FROM   table_name
WHERE  column_name GLOB { PATTERN };

    SQLite GROUP BY 子句

    SELECT SUM(column_name)
FROM   table_name
WHERE  CONDITION
GROUP BY column_name;

    SQLite HAVING 子句

    SELECT SUM(column_name)
FROM   table_name
WHERE  CONDITION
GROUP BY column_name
HAVING (arithematic function condition);

    SQLite INSERT INTO 语句

    INSERT INTO table_name( column1, column2....columnN)
VALUES ( value1, value2....valueN);

    SQLite IN 子句

    SELECT column1, column2....columnN
FROM   table_name
WHERE  column_name IN (val-1, val-2,...val-N);

    SQLite Like 子句

    SELECT column1, column2....columnN
FROM   table_name
WHERE  column_name LIKE { PATTERN };

    SQLite NOT IN 子句

    SELECT column1, column2....columnN
FROM   table_name
WHERE  column_name NOT IN (val-1, val-2,...val-N);

    SQLite ORDER BY 子句

    SELECT column1, column2....columnN
FROM   table_name
WHERE  CONDITION
ORDER BY column_name {ASC|DESC};

    SQLite PRAGMA 语句

    PRAGMA pragma_name;

For example:

PRAGMA page_size;
PRAGMA cache_size = 1024;
PRAGMA table_info(table_name);

    SQLite RELEASE SAVEPOINT 语句

    RELEASE savepoint_name;

    SQLite REINDEX 语句

    REINDEX collation_name;
REINDEX database_name.index_name;
REINDEX database_name.table_name;

    SQLite ROLLBACK 语句

    ROLLBACK;
or
ROLLBACK TO SAVEPOINT savepoint_name;

    SQLite SAVEPOINT 语句

    SAVEPOINT savepoint_name;

    SQLite SELECT 语句

    SELECT column1, column2....columnN
FROM   table_name;

    SQLite UPDATE 语句

    UPDATE table_name
SET column1 = value1, column2 = value2....columnN=valueN
[ WHERE  CONDITION ];

    SQLite VACUUM 语句

    VACUUM;

    SQLite WHERE 子句

    SELECT column1, column2....columnN
FROM   table_name
WHERE  CONDITION;

    SQLite 没有 ANY 和 ALL

    ANY：任一，ALL：所有

    速记

    /*
多行注解
*/

-- 单行注解

select * from students;
select 姓名,班级,成绩 from students;
select 姓名,班级,成绩 from students limit 5;
select 姓名,班级,成绩 from students limit 5 offset 5;
select 姓名,班级,成绩 from students where 班级 = '一年二班';
select 姓名,班级,成绩 from students where 班级 != '一年二班';
select 姓名,班级,成绩 from students where 班级 != '一年二班'  order by 班级;
select 姓名,班级,成绩 from students where 班级 != '一年二班'  order by 班级, 成绩;
select 姓名,班级,成绩 from students where 班级 != '一年二班'  order by 班级, 成绩 desc;
select 姓名,班级,成绩 from students where 姓名 = '张三';
select 姓名,班级,成绩 from students where 姓名 like '张%'; -- 匹配0个或者多个
select 姓名,班级,成绩 from students where 姓名 like '张_'; -- 匹配 1 个
select 姓名,班级,成绩 from students where 成绩 >= 80 and 成绩 <90;
select 姓名,班级,成绩 from students where 成绩 between 80 and  90;
select 姓名,班级,成绩 from students where 成绩 between 80 and  90 and 班级 = '一年二班';
select 姓名,班级,成绩 from students where 成绩 between 80 and  90 and (班级 = '一年一班' or 班级 = '一年二班');
select 姓名,班级,成绩 from students where 成绩 between 80 and  90 and (班级 in ('一年一班' , '一年二班'));
select avg(成绩),sum(成绩),max(成绩),min(成绩), count(成绩) from students;
select avg(成绩) as 成绩平均 ,max(成绩) as 最高分 from students;
select round(avg(成绩), 1) as 成绩平均 ,max(成绩) as 最高分 from students;
select round(avg(成绩)) as 成绩平均  from students;
select 班级,round(avg(成绩)) as 成绩平均  from students group by 班级;
select 班级,round(avg(成绩)) as 成绩平均  from students group by 班级 order by 成绩平均 desc;

    顺序：

    select
from
where
group by
having
order by
limit
    select count(*) from students; -- 计算总行数
select count(社团) from students; -- 计算社团行数，count 排除空值
select count(distinct 社团) from students; -- 排除重复
select distinct 社团 from students; -- distinct 不排除空值
select distinct 社团 from students where 社团 != null;

create table clubs(
社团编号 int primary key,
社团名称 varchar(15)
);

drop table clubs2;

insert into clubs (社团编号, 社团名称) values (101, '吉他社'), (102, '美术社'), (104, null);

update clubs set 社团名称 = '舞蹈社' where 社团编号 = 104;

delete from clubs where  社团编号 = 104;

select students.姓名, students.社团, clubs.社团名称 from students left join clubs on students.社团 = clubs.社团编号 where 班级 = '一年一班'; -- left join 左侧所有记录，例如没有报名社团的同学，或者报名的社团没找到名称的同学也会显示

select students.姓名, students.社团, clubs.社团名称 from students inner join clubs on students.社团 = clubs.社团编号 where 班级 = '一年一班'; -- inner join 只会显示左右两表能对应上的元素