11.SQL语言是__C__语言。 A.层次数据库; B.网络数据库; C.关系数据库; D.非数据库; 12. SQL语言具有____的功能。 A.关系规范化,数据操作,数据控制; B.数据定义,数据操作,数据控制; C.数据定义,关系规范化,数据控制; D.数据定义,关系规范化,数
A.层次数据库;
B.网络数据库;
C.关系数据库;
D.非数据库;
12. SQL语言具有____的功能。
A.关系规范化,数据操作,数据控制;
B.数据定义,数据操作,数据控制;
C.数据定义,关系规范化,数据控制;
D.数据定义,关系规范化,数据操作;
13.下列SQL语句中,修改表结构的是__A__。
A.ALTER ;
B.CREATE ;
C.UPDATE ;
D.INSERT ;
14.SQL语言中,实现数据检索的语句是____。
A.SELECT ;
B.INSERT ;
C.UPDATE ;
D.DELETE ;
15. SQL中,与“NOT IN”等价的操作符是____。
A.=SOME ;
B.SOME ;
C.=ALL ;
D.ALL ;
16. Access 2000 是__D__类型的软件。
A.文字处理;
B.电子表格;
C.演示软件;
D.数据库;
17.在Access文件的扩展名是__C__。
A.Doc ;
B.xls ;
C.mdb ;
D.ppt ;
18.数据库中1:N的关系可以表现在__D__。
A.学校校长与下属院长的关系;
B.医院病床与病人的关系;
C.学生与班主任的关系;
D.飞机与机械师的关系;
19.数据库表的外关键字是__A__部分。
A.另一个表的关键字;
B.是本表的关键字;
C.与本表没关系的;
D.都不对;
20.数据库DB、数据库系统DBS、数据库管理系统DBMS三者之间的关系是____。
A.DB包含DBS、DBMS;
B.DBS包含DB、DBMS;
C.DBMS包含DB、DBS;
D.三者互不包含;

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Best practices for handling string data types and indexes in MySQL include: 1) Selecting the appropriate string type, such as CHAR for fixed length, VARCHAR for variable length, and TEXT for large text; 2) Be cautious in indexing, avoid over-indexing, and create indexes for common queries; 3) Use prefix indexes and full-text indexes to optimize long string searches; 4) Regularly monitor and optimize indexes to keep indexes small and efficient. Through these methods, we can balance read and write performance and improve database efficiency.


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