[转]SQLite 经验集

SQLite 的默认时间 转自：http://www.cnblogs.com/pennant/archive/2011/08/11/2134897.html

select strftime('%Y-%m-%d %H:%M:%S','now')

这个查询的结果是 UTC时间，即 +8h 才和电脑时间相同。

select time('now')

这个查询的结果是 01:02:03 ，也要 +8h 才和电脑时间相同。

select date('now')

这个查询的结果是 2017-03-02

select datetime('now')

这个查询的结果是 2017-03-02 01:02:03 

　　%d 一月中的第几天01-31

　　%f 小数形式的秒，SS.SSSS

　　%H 小时00-24

　　%j 一年中的第几天01-366

　　%J Julian Day Numbers

　　%m 月份01-12

　　%M 分钟00-59

　　%s 从1970-01-01日开始计算的秒数

　　%S 秒00-59

　　%w 星期，0-6，0是星期天

　　%W 一年中的第几周00-53

　　%Y 年份0000-9999

　　%% %百分号

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SQLite: Data Types - 数据类型

The following is a list of datatypes available in SQLite, which includes string, numeric, date/time, and large object datatypes.

For simplicity's sake, SQLite essentially uses these basic datatypes:

• TEXT
• INTEGER
• NUMERIC
• REAL
• NONE

To be compatible with other SQL databases, SQLite allows you to use the common datatype names that you've seen in other databases and maps them to their basic SQLite datatypes (listed above).

Let's look at the common datatypes names that SQLite lets you define.

String Datatypes

All string datatypes in SQLite are converted to a TEXT datatype. If you try to specify a size for a string datatype, SQLite will ignore it, as it does not allow size restrictions on string datatypes.

The following are the String Datatypes in SQLite:

Data Type Syntax	Explanation
CHAR(size)	Equivalent to TEXT (size is ignored)
VARCHAR(size)	Equivalent to TEXT (size is ignored)
TINYTEXT(size)	Equivalent to TEXT (size is ignored)
TEXT(size)	Equivalent to TEXT (size is ignored)
MEDIUMTEXT(size)	Equivalent to TEXT (size is ignored)
LONGTEXT(size)	Equivalent to TEXT (size is ignored)
NCHAR(size)	Equivalent to TEXT (size is ignored)
NVARCHAR(size)	Equivalent to TEXT (size is ignored)
CLOB(size)	Equivalent to TEXT (size is ignored)

Numeric Datatypes

All numeric datatypes in SQLite are converted to INTEGER, NUMERIC, or REAL datatypes.

The following are the Numeric Datatypes in SQLite:

Data Type Syntax	Explanation
TINYINT	Equivalent to INTEGER
SMALLINT	Equivalent to INTEGER
MEDIUMINT	Equivalent to INTEGER
INT	Equivalent to INTEGER
INTEGER	Equivalent to INTEGER
BIGINT	Equivalent to INTEGER
INT2	Equivalent to INTEGER
INT4	Equivalent to INTEGER
INT8	Equivalent to INTEGER
NUMERIC	Equivalent to NUMERIC
DECIMAL	Equivalent to NUMERIC
REAL	Equivalent to REAL
DOUBLE	Equivalent to REAL
DOUBLE PRECISION	Equivalent to REAL
FLOAT	Equivalent to REAL
BOOLEAN	Equivalent to NUMERIC

Date/Time Datatypes

All date or time datatypes in SQLite are converted to NUMERIC datatypes.

The following are the Date/Time Datatypes in SQLite:

Data Type Syntax	Explanation
DATE	Equivalent to NUMERIC
DATETIME	Equivalent to NUMERIC
TIMESTAMP	Equivalent to NUMERIC
TIME	Equivalent to NUMERIC

Large Object (LOB) Datatypes

The following are the LOB Datatypes in SQLite:

Data Type Syntax	Explanation
BLOB	Equivalent to NONE