Excerpt:
Today saw a sql statistics subject, requires the preparation of statistics to another table sql already known according to the table. Demand is such that there is a teacher table records every day there is a teacher in the curriculum, the table structure is as follows:
The sql is correct, the statement with group by, the query must be field after the group by or statistical functions , then this sum is based on statistical data inside the packet of every row. learned.
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