急问：quality analyst 对 sql 的要求有多高？

job deion 的原文是：ability to write and understand complex SQL queries and use reporting tools such as Crystal and MS Reporting Services.没有提到是哪种database system。 不知道他们说的complex SQL queries有多complex?
不知道从哪方面准备，没有reporting tools的经验。请高人指点！！多谢！！