神马作文网帮我解释一下这条sql语句的意思
来源：学生作业帮 编辑：神马作文网作业帮 分类：综合作业 时间：2024/09/22 22:25:30
帮我解释一下这条sql语句的意思
select month01.pk_deptdoc as dept,month01.amot as month01,month02.amot as month02
from
(select h.pk_deptdoc,sum(expense_amot) as amot from te_expense_b b left join te_expense h on b.pk_expense=h.pk_expense
where h.dbilldate>='2013-01-01' and h.dbilldate='2013-02-01' and h.dbilldate
select month01.pk_deptdoc as dept,month01.amot as month01,month02.amot as month02
from
(select h.pk_deptdoc,sum(expense_amot) as amot from te_expense_b b left join te_expense h on b.pk_expense=h.pk_expense
where h.dbilldate>='2013-01-01' and h.dbilldate='2013-02-01' and h.dbilldate
这个语句就是一个查询里面嵌套查询的语句,month01,month02作为子查先查询出结果再进行连接进行查询.