mediumtexthive 里的时间是什么数据类型

PostgreSQL数据库中char，varchar和text的区别

char 是固定长度，长度0-255； varchar 是可变长度的字符串，不足时不会补空格，超过时会自动截断，长度0-255； text 是长文本字符串，长度0-65535 此外，还有MEDIUMTEXT，LONGTEXT等

MySQL字段类型都是什么意思？

MySQL的字段类型 char(length) char类型最大长度是255个字符。

当插入到表中的字符串的长度小于length时候，将给字段右边不够的部分用空格填补。

varchar(length) varchar的最大长度是255个字符。

varchar和char几乎一样，区别在于varchar是变长的类型，不会填补空格。

tinytext tinytext最大长度是255字符。

text text最大长度是65535(2的17次方)字符。

mediumtext mediumtext最大长度是16777215个字符。

longtext longtext最大长度是4294976259个字符。

(tinytext,text,mediumtext,longtext这四种类型，都是可边长字段类型，与varchar一样，只是最大长度不同而已) VARCHAR，BLOB和TEXT类型是变长类型，对于其存储需求取决于列值的实际长度，而不是取决于类型的最大可能尺寸。

例如，一个VARCHAR(10)列能保存最大长度为10个字符的一个字符串，实际的存储需要是字符串的长度，加上1个字节以记录字符串的长度。

对于字符串’abcd’，长度是4而存储要求是5个字节。

BLOB和TEXT类型需要1，2，3或4个字节来记录列值的长度，这取决于类型的最大可能长度。

VARCHAR需要定义大小，有255的最大限制；TEXT则不需要。

如果你把一个超过列类型最大长度的值赋给一个BLOB或TEXT列，值被截断以适合它。

在数据库中“mediumtext”和“text”有什么区别？

这两个的区别是长度不同。

MEDIUMTEXT ：一个BLOB或TEXT列，最大长度为16777215(2^24-1)个字符。

? TEXT ：一个BLOB或TEXT列，最大长度为65535(2^16-1)个字符。

数据库是按照数据结构来组织、存储和管理数据的仓库，它产生于距今六十多年前，随着信息技术和市场的发展，特别是二十世纪九十年代以后，数据管理不再仅仅是存储和管理数据，而转变成用户所需要的各种数据管理的方式。

数据库有很多种类型，从最简单的存储有各种数据的表格到能够进行海量数据存储的大型数据库系统都在各个方面得到了广泛的应用。

在信息化社会，充分有效地管理和利用各类信息资源，是进行科学研究和决策管理的前提条件。

数据库技术是管理信息系统、办公自动化系统、决策支持系统等各类信息系统的核心部分，是进行科学研究和决策管理的重要技术手段。

mediumtext是什么类型

@Lob(type = LobType.CLOB, fetch = FetchType.LAZY) @Column(length = 16777216) 在string类型上加上这两句注解试试

sphinx是什么？

Egyptian sphinxes In Ancient Egyptian mythology, a Sphinx is a zoomorphic figure, usually depicted as a recumbent lioness or lion with a human head, but asionally with the head of a falcon, hawk, or ram. The figure had its origin in the Old Kingdom and is associated with the solar deity Sekhmet, who also was the fierce war deity and protector of the pharaohs. She remained as a strong figure in Egyptian religion throughout its history, even during the Amarna period. The sphinx were often described as Sekhmet's children.[clarify] The use of heads of other animals the lioness body followed the titularly deities of the city or region where they were built or which were prominent in the Egyptian pantheon at the time. Generally the roles of sphinxes were as temple guardians and they were placed in association with architectural structures such as royal tombs or religious temples. Later, the sphinx image, or something very similar to the original Egyptian concept, was imported into many other cultures, albeit often interpreted quite differently due to translations of descriptions of the originals and the evolution of the concept in relation to other cultural traditions. Perhaps the first sphinx, Hetepheres II from the fourth dynasty - Cairo MuseumPerhaps the first sphinx was one depicting Hetepheres II, of the fourth dynasty that lasted from 2723 to 2563 BC. The largest and most famous is the Great Sphinx of Giza, sited at the Giza Plateau on the west bank of the Nile River and facing due east, is also from the same dynasty ( 29°58′31″N, 31°08′15″E). Although the date of its construction is uncertain, the head of the Great Sphinx now is believed to be that of the pharaoh Khafra. Avenue of ram-headed sphinxes at Karnak in Luxor dating to the eighteenth dynastyWhat names their builders gave to these statues is not known. Probably having been erected a thousand years later, in 1400 BCE, by Thutmose IV the inscription on a stele at the Great Sphinx site lists the names of three aspects of the local sun deity of that period, Khepera - Re - Atum. The inclusion of these figures in tomb and plexes quickly became traditional and many pharaohs had their heads carved the guardian statues for their tombs to show their close relationship with the powerful deity, Sekhmet. Other famous Egyptian sphinxes include one bearing the head of the pharaoh Hatshepsut, with her likeness carved in granite, which is now in the Metropolitan Museum of Art in New York, and the alabaster sphinx of Memphis, currently located within the open-air museum at that site. The theme was expanded to great avenues of guardian sphinxes lining the avenues to tombs and temples as well as serving as details the posts of flights of stairs to very plexes. Nine hundred with rams' heads, representing Amon, were built in Thebes, where his cult was strongest.

hive 里的时间是什么数据类型

HIVE里有两种时间类型:DATE类和TIMESTAMP类 DATE类保存形如‘2017-05-05 00:00:00.000’这种数据, TIMESTAMP保存的是一个10位的整数, 即UNIX系统下的时间戳记法。

可以通过from_unixtime()和unix_timestamp()函数互相转换。

当然你也可以直接存成string格式。