接触SQLite已经很久了，没有怎么用过。最近在做一个东西，用到SQLite，打算自现在开始，把自己当成一个新手来接触SQLite（也的确是新手）。
先找个地方下个管理数据库的工具吧。
当前遇到的第一个问题：[六子文章]
1：如何用SQL语句，修改数据库表中列的数据类型？
2：如何应用参数？
3：删除数据库表中的记录。
Delete FROM Recorder
4：删除数据库表
DROP TABLE Recorder
5：取得前9条记录
SELECT * FROM Recorder limit 9
6：建立测试数据库：
１）RecType
花销类型表：
CREATE TABLE RecType (RecTypeId integer NOT NULL, RecTypeName [varchar](20) NOT NULL, PRIMARY KEY(RecTypeId))
表描述：
字段名称 数据类型 数据长度 字段描述 默认值 标识 可为空
==============================
RecTypeId, int, 4, 花销类型编号, , 是, 不可
----------------------------------------
RecTypeName, varchar, 20, 花销类型名称, , 不是, 不可
----------------------------------------
==============================
主键为
RecTypeId
２）Recorder
CREATE TABLE [Recorder] (
[RedId] integer NOT NULL ,
[CreateDate] [datetime] NOT NULL default CURRENT_TIMESTAMP,
[RecDate] [date] NOT NULL ,
[RecType] [int] NOT NULL ,
[RecValue] [decimal](18, 2) NOT NULL ,
[Remark] [varchar] (500) NULL ,
PRIMARY KEY(RedId)
)
表描述：
字段名称 数据类型 数据长度 字段描述 默认值 标识 可为空
[六子文档：ｕｒｌ：admin11.cnblogs.com]
==============================
RedId, int, 4, 记录ID, , 是, 不可
----------------------------------------
CreateDate, datetime, 8, 记录时间, (getdate()), 不是, 不可
----------------------------------------
RecDate, smalldatetime, 4, 花销日期, , 不是, 不可
----------------------------------------
RecType, int, 4, 花销类型, , 不是, 不可
----------------------------------------
RecValue, decimal, 9, 花销金额, , 不是, 不可
----------------------------------------
Remark, varchar, 500, 备注, , 不是, 可
----------------------------------------
==============================
主键为
RedId
六子文档：ｕｒｌ：admin11.cnblogs.com
7：T_SQL语句转换成SQLite语句
// 取得数据库表中的月份数量
T_SQL：
select count(distinct DATEPART(month, RecDate)) AS CounRecs from recorder
SQLite：
SELECT COUNT(1) FROM (SELECT distinct substr(RecDate, 0, 6) FROM recorder) AS Month
问题：
substr(RecDate, 0, 6 ) 适用于类似2006-5-10而不能适用于2006-05-10这样的日期，具体如何处理，暂时还不知道。
[六子文档：ｕｒｌ：admin11.cnblogs.com]
// 取得数据库中某列的值总合。
T_SQL：
select sum(recvalue) as recvalue from recorder
SQLite：
select sum(recvalue) as recvalue from recorder
两个语句是一样的
7：复杂的句子：
取得数据库中的月份总数和月平均值
T_SQL：
select cast(recvalue/CounRecs AS Money) AS PercentValue,recvalue, CounRecs AS Days
from (select sum(recvalue) as recvalue from recorder )SumValue,(select count(distinct DATEPART(month, RecDate)) AS CounRecs from recorder ) CountRec
SQLite：
select recvalue/CounRecs AS PercentValue,recvalue, CounRecs AS Days from (select sum(recvalue) as recvalue from recorder) AS SumValue, (SELECT COUNT(1) as CounRecs FROM (SELECT distinct substr(RecDate, 0, 6) FROM recorder)) As CountRec
注：本语句中的Days 列其实为月份数
// 取得当前记录的记录日期，金额总数，平均化小。（每日）
T_SQL：
select Cast(recvalue/CounRecs AS Money) AS PercentValue,recvalue, CounRecs AS Days from (select sum(recvalue) as recvalue from recorder)SumValue,(select count(distinct convert(varchar(10),recdate,120)) AS CounRecs from recorder ) CountRec
ＳＱＬｉｔｅ：
SELECT recvalue/CounRecs AS PercentValue,recvalue, CounRecs AS Days from (select sum(recvalue) as recvalue from recorder ) as SumValue, (SELECT COUNT(1) as CounRecs FROM (SELECT distinct substr(RecDate, 0, 9) FROM recorder) daynum) as CounRec
[六子文档：ｕｒｌ：admin11.cnblogs.com]
// 简单的视图操作：
// 分类花销记录
// Ｔ_SQL 语句：
SELECT Sum(RecValue) AS SumVAalue, RecTypeName, COUNT(1) AS SaleTime FROM V_Recorder Group By RecTypeName
// SQLite语句：
SELECT Sum(RecValue) AS SumVAalue, RecTypeName, COUNT(1) AS SaleTime FROM V_Recorder Group By RecTypeName
两个语句是一样的