【单选题】从同批药材包件中抽取共检验样品的原则,以下说法错误的是。(
【单选题】从同批药材包件中抽取供检验样品的原则,以下说法错误的是
【单选题】从同批药材包件中抽取检定用样品的原则,正确的是()
【简答题】甲企业现金收支状况平稳,预计全年 ( 按 360 天计算 ) 需要现金 12 万元,现金与有价证券的转换成本为每次 800 元,有价证券的月利率为 1% 。 要求: (1) 计算最佳现金持有量; (2) 计算最低现金管理相关总成本; (3) 计算转换成本和机会成本; (4) 计算有价证券交易次数及有价证券交易间隔期。
【单选题】Consider the query: Mysql> SET @run = 15; Mysql> EXPLAIN SELECT objective, stage, COUNT (stage) FROM iteminformation WHERE run=@run AND objective=’7.1’ GROUP BY objective,stage ORDER BY stage; The ite...
A.
Do not pass a user variable in the WHERE clause because it limits the ability of the optimizer to use indexes
B.
Add an index on the objective column so that is can be used in both the WHERE and GROUP BY operations
C.
Drop the run_2 index because it has caused a conflict in the choice of key for this query
D.
Execute the run_2 index because it has caused a conflict in the choice of key for this query
E.
Add a composite index on (run,objective,stage) to allow the query to fully utilize an index
【多选题】下面关于mysql_query ($query,$link )说法正确的是( )。
A.
第一个参数是SQL语句,第二个参数是链接对象。
D.
如不指定链接对象,则使用由mysql_connect()最近打开的连接。
【单选题】阅读以上代码,请问该代码的功能是( )。