SQLite所支持的数据类型_动视

SQLite所支持的数据类型

2020-11-09 11:36:25 责编:小采

上次工作需要学了一个月的mysql，不久知道好多东西都忘掉了，现在由于工作需要再学点sqlite，其实都差不多,Sqlite3支持的数据类型

NULL，INTEGER，REAL，TEXT，BLOB

以及：
smallint 16 位元的整数。
interger 32 位元的整数。
decimal(p,s) p 精确值和 s 大小的十进位整数，精确值p是指全部有几个数(digits)大小值，s是指小数点後有几位数。如果没有特别指定，则系统会设为 p=5; s=0 。
float 32位元的实数。
double 位元的实数。
char(n) n 长度的字串，n不能超过 254。
varchar(n) 长度不固定且其最大长度为 n 的字串，n不能超过 4000。
graphic(n) 和 char(n) 一样，不过其单位是两个字元 double-bytes， n不能超过127。这个形态是为了支援两个字元长度的字体，例如中文字。
vargraphic(n) 可变长度且其最大长度为 n 的双字元字串，，n不能超过 2000
date 包含了年份、月份、日期。
time 包含了小时、分钟、秒。

timestamp 包含了年、月、日、时、分、秒、千分之一秒。

表1-1

type description

TINYBLOB, BLOB, MEDIUMBLOB, LONGBLOB, BYTEA String types of unlimited length. Binary data must be safely encoded, see text.

CHAR(), VARCHAR(), TINYTEXT, TEXT, MEDIUMTEXT, LONGTEXT String types of unlimited length. There is no chopping or padding performed by the database engine.

ENUM String type of unlimited length. In contrast to MySQL, choosing ENUM over VARCHAR does not save any storage space.

SET String type of unlimited length. In contrast to MySQL, the input is not checked against the list of allowed values.

YEAR String type of unlimited length. MySQL stores 2 or 4 digit years as a 1 byte value, whereas the SQLite drivers stores the string as provided.

TINYINT, INT1, CHAR A 1 byte type used to store one character, a signed integer between -128 and 127, or an unsigned integer between 0 and 255.

SMALLINT, INT2 2 byte (short) integer type used to store a signed integer between -32768 and 32767 or an unsigned integer between 0 and 65535.

MEDIUMINT 3 byte integer type used to store a signed integer between -8388608 and 8388607 or an unsigned integer between 0 and 16777215.

INT, INTEGER, INT4 4 byte (long) integer type used to store a signed integer between -21474838 and 21474837 or an unsigned integer between 0 and 4294967295.

BIGINT, INT8, INTEGER PRIMARY KEY 8 byte (long long) integer type used to store a signed integer between -9223372036854775808 and 9223372036854775807 or an unsigned integer between 0 and 18446744073709551615. See below for a discussion of INTEGER PRIMARY KEY.

DECIMAL, NUMERIC A string type of unlimited length used to store floating-point numbers of arbitrary precision.

TIMESTAMP, DATETIME A string type of unlimited length used to store date/time combinations. The required format is 'YYYY-MM-DD HH:MM:SS', anything following this pattern is ignored.

DATE A string type of unlimited length used to store a date. The required format is 'YYYY-MM-DD', anything following this pattern is ignored.

TIME A string type of unlimited length used to store a time. The required format is 'HH:MM:SS', anything following this pattern is ignored.

FLOAT, FLOAT4, REAL A 4 byte floating-point number. The range is -3.402823466E+38 to -1.175494351E-38, 0, and 1.175494351E-38 to 3.402823466E+38. Please note that MySQL treats REAL as an 8 byte instead of a 4 byte float like PostgreSQL.

DOUBLE, DOUBLE PRECISION, FLOAT8 An 8 byte floating-point number. The range is -1.7976931348623157E+308 to -2.2250738585072014E-308, 0, and 2.2250738585072014E-308 to 1.7976931348623157E+308.

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