单项选择题
A.Bob has max_user_connections set to zero, which blocks all his connections
B.Joe has exceeded the max_user_connections global limit
C.All users are blocked because max_user_connections is accumulated over the host account information
D.Kay is already connected elsewhere and attempting to log in again
E.Connect_timeout is too small to allow a connection to occur
单项选择题 Your developers have created table to store some of their programs data. After examining the slow Query Log, you see that they are using the LIKE operator and SUBSTER () functions against a VARCHAR (10000) column quite often. An example of the start of one row of data: GREEN01020495888331993-12-10/2… What should you do to improve the overall performance?（）
多项选择题 Which three are properties of the MyISAM storage engine?（）
多项选择题 You need to replicate a table from a master to a slave. The master and slave copies of the table will have different number of columns. Which two conditions must be true?（）
