A database administrator wants to create an index on the address column in the CUSTOMER_MSTR table. Their statement is below:
CREATE INDEX ADDRESS ON CUSTOMER_MSTR (Address(64));
You think the index can be a lot shorter and therefore more efficient. Write an example SQL query that you could run to show that an index based on Address with a length of 32 characters is just as good as one with a length of 64 characters.
题目说在CUSTOMER_MSTR表中在address建一个index如下:
CREATE INDEX ADDRESS ON CUSTOMER_MSTR (Address(64));
你认为index没必要那么长因此能够更加有效。写一个可以运行的SQL查询来表明32个字母长度的地址和64个长度的地址运行一样好?
有sql的专家来说说吗
希望能写出完整的query,插入数据insert可以省略