我对这些术语的起源感兴趣. sql发明了吗？他们是否已经在历史上用于其他数据库？是否有其他标准创建它们,它们是否被sql使用？或者sql是否甚至在ISO规范中使用它们？
一本书表明sql92包含这些术语,但我无法在线提供的草稿中找到它们. (也许我必须购买最终的sql92 ISO规范才能确定.)sql：1999切换到不同的分类系统.
(我很好奇的一个原因是,如果这些是sql不发明的一般行业术语,那么继续使用它们并不一定是不正确的,这是对新sql分类的补充.)
任何人都可以提供有关这些术语起源的更多信息,以及对最初可能定义它们的任何标准或规范的权威参考吗？
解决方法
The concept of the data definition language and its name was first
introduced in relation to the Codasyl database model,where the schema
of the database was written in a language Syntax describing the
records,fields,and sets of the user data model.[1] Later it was used
to refer to a subset of Structured Query Language (sql) for declaring
tables,columns,data types and constraints. sql-92 introduced a
schema manipulation language and schema information tables to query
schemas. These information tables were specified as sql/Schemata in
sql:2003. The term DDL is also used in a generic sense to refer to any
formal language for describing data or information structures.
Wikipedia’s “Codasyl” entry提供了更多细节：
In October 1969 the DBTG published its first language specifications
for the network database model which became generally known as the
CODASYL Data Model. This specification in fact defined several
separate languages: a data definition language (DDL) to define the
schema of the database,another DDL to create one or more subschemas
defining application views of the database; and a data manipulation
language (DML) defining verbs for embedding in the COBOL programming
language to request and update data in the database. Although the work
was focused on COBOL,the idea of a host-language independent database
was starting to emerge,prompted by IBM’s advocacy of PL/I as a COBOL
replacement.
“Data Base Task Group” Wikipedia entry表示它在2年后发布了一份最终报告：
In April 1971,the DBTG published a report containing specifications
of a Data Manipulation Language (DML) and a Data Definition Language
(DDL) for standardization of network database model. The first DBTG
proposals had already been published in 1969. The specification was
subsequently modified and developed in varIoUs committees and
published by other reports in 1973 and 1978. The specification is
often referred to as the DBTG database model or the CODASYL database
model. As well as the data model,many basic concepts of database
terminology were introduced by this group,notably the concepts of
schema and subschema.
以上涵盖DDL和DML.不幸的是Wikipedia’s “Data control language” entry在撰写本文时没有太多细节,我无法在其他地方找到这个术语的起源.但考虑到上面和下面显示的Google Ngram graph,可能会怀疑它是在晚些时候出现的 – 可能是在20世纪70年代中期.
并且here is another graph显示了支持这一点的所有三个术语：
