What is true about joining tables through an equijoin?
A. You can join a maximum of two tables through an equijoin.
B. You can join a maximum of two columns through an equijoin.
C. You specify an equijoin condition in the SELECT or FROM clauses of a SELECT statement.
D. To join two tables through an equijoin, the columns in the join condition must be primary key and foreign
key columns.
E. You can join n tables (all having single column primary keys) in a SQL statement by specifying a minimum
of n-1 join conditions.
Answer: E
这道题目是啥意思?我没有看懂!
------解决方案--------------------------------------------------------
下面哪个关于等值连接的说法是正确的?
A 你最多只能做两个表的等值连接
B 等值连接最多只能连接两个字段
C 你能在select语句或者from语句中做等值连接
D 只能使用主键或外键做等值连接的条件
E 最少n-1个连接条件就能连接n张表(所有表的主键都只有一列)
毫无疑问,只有E是正确的
------解决方案--------------------------------------------------------
赶鸭子上架,不得不努力学习英语
------解决方案--------------------------------------------------------
学习。