MySQL's aggregation function

1.AVG ()

Usage: Averaging

Example:

Mysql> Select *  fromT1;+----+------+----------+---------+-------+-------+|Id|Name|Password|test001|Test3|Test4|+----+------+----------+---------+-------+-------+|  2 | 1    | 1        | 1       | 1     | 1     ||  3 | 3    | 4        | 5       | 6     | 7     ||  4 | 3    | 4        | 5       | 6     | 7     ||  5 | 3    | 4        | 5       | 6     | 7     ||  6 | 3    | 4        | 5       | 6     | 7     ||  7 | 3    | 4        | 5       | 6     | 7     ||  8 | 3    | 4        | 5       | 6     | 7     ||  9 | 3    | 4        | 5       | 6     | 7     || Ten | 3    | 4        | 5       | 6     | 7     |+----+------+----------+---------+-------+-------+9Rowsinch Set(0.00sec) MySQL> Select AVG(ID) fromT1;+---------+| AVG(ID)|+---------+|  6.0000 |+---------+1Rowinch Set(0.00Sec

2.COUNT ()

Usage: Record number of bars

Example:

Mysql> Select COUNT(ID) fromT1;+-----------+| COUNT(ID)|+-----------+|         9 |+-----------+1Rowinch Set(0.00Sec

3.MAX ()

Usage: Returns the maximum value

Example:

Mysql> Select MAX(ID) fromT1;+---------+| MAX(ID)|+---------+|      Ten |+---------+1Rowinch Set(0.01Sec

4.MIN ()

Usage: Returns the minimum value

Example:

Mysql> Select MIN(ID) fromT1;+---------+| MIN(ID)|+---------+|       2 |+---------+1Rowinch Set(0.00Sec

5.SUM ()

Usage: Sum

Example:

Mysql> Select SUM(ID) fromT1;+---------+| SUM(ID)|+---------+|       Wu |+---------+1Rowinch Set(0.00Sec

Others: MD5 (), PASSWORD ()

Mysql> SelectMD5 ('MYSQL');+----------------------------------+|MD5 ('MYSQL')|+----------------------------------+|14498b83dd1667a0c78f4fdaf5afbf4b|+----------------------------------+1Rowinch Set(0.00sec) MySQL> SelectPASSWORD ('MYSQL');+-------------------------------------------+|PASSWORD ('MYSQL')|+-------------------------------------------+| *a97af8e14502c1b988202fb7b96cf565b6523f9d|+-------------------------------------------+1Rowinch Set(0.00sec) MySQL> SelectEncypt ('MYSQL'); ERROR1305(42000):FUNCTIONTest. Encypt does notExistmysql> SelectENCRYPT ('MYSQL');+------------------+|ENCRYPT ('MYSQL')|+------------------+| NULL             |+------------------+1Rowinch Set(0.03Sec

MySQL's aggregation function