SQL group by syntax and example

SQL group by syntax and example

Group by statement

The group by statement is used in combination with the aggregate function to group result sets based on one or more columns.

SQL group by syntax

Select column_name, aggregate_function (column_name)

From table_name

Where column_name operator value

Group by column_name

Let's look at a group by instance.

For example, the content in the table is as follows:

Gameid best top spam

111 1 1 1

121 1 1 0

123 0 1 1

111 1 0 1

The result of getting the best top spam number is

Gameid best top spam

111 2 1 2

121 1 1 0

123 0 1 1

Select gameid, sum (best) as bestcnt, sum (top) as tocnt, sum (spam) as spamcnt

From table

Group by gameid

How to use it in the php tutorial

$ SQL = "select gameid, sum (best) as best, sum (top) as top, sum (spam) as spam, from tablename group by gameid order by gameid asc ";

Let's look at a simple example.

Database tutorial table

Win or lose by date

-9 wins

-9 wins

2009-12-9 negative

2009-12-9 negative

2009-12-10 negative

-12-10 wins

2009-12-10 negative

Query Result

Date wins/loses

2009-12-9 2 2

2009-12-10 1 2

Select date,

Sum (decode (winning, winning )),

Sum (decode (winning or losing, 'negative ))

From database table

Group by date