sqlite

Database; use; embedded relational database

group

UK[gru:p] US [ɡrup]

n. Group, group; group, batch; (sculpture, etc.) group portrait; (British and American) Air Force Brigade

vt.& vi. To form a group, to gather

vt. Classification, classification

by

英[baɪ] 美[baɪ]

prep.Beside...; means Method; because; pass

adv. pass; used when expressing retention or preservation; short visit

SQLite Group By function syntax

Function:SQLite's GROUP BY clause is used with the SELECT statement to group the same data.

In the SELECT statement, the GROUP BY clause is placed after the WHERE clause and before the ORDER BY clause.

Syntax: The basic syntax of the GROUP BY clause is given below. The GROUP BY clause must be placed after the condition in the WHERE clause and before the ORDER BY clause.

SELECT column-list
FROM table_name
WHERE [ conditions ]
GROUP BY column1, column2....columnN
ORDER BY column1, column2....columnN

You can use multiple columns in the GROUP BY clause. Make sure the grouping you are using is listed in the column list.

SQLite Group By function example

 COMPANY 表有以下记录：

ID          NAME        AGE         ADDRESS     SALARY
----------  ----------  ----------  ----------  ----------
1           Paul        32          California  20000.0
2           Allen       25          Texas       15000.0
3           Teddy       23          Norway      20000.0
4           Mark        25          Rich-Mond   65000.0
5           David       27          Texas       85000.0
6           Kim         22          South-Hall  45000.0
7           James       24          Houston     10000.0
如果您想了解每个客户的工资总额，则可使用 GROUP BY 查询，如下所示：

sqlite> SELECT NAME, SUM(SALARY) FROM COMPANY GROUP BY NAME;
这将产生以下结果：

NAME        SUM(SALARY)
----------  -----------
Allen       15000.0
David       85000.0
James       10000.0
Kim         45000.0
Mark        65000.0
Paul        20000.0
Teddy       20000.0
现在，让我们使用下面的 INSERT 语句在 COMPANY 表中另外创建三个记录：

INSERT INTO COMPANY VALUES (8, 'Paul', 24, 'Houston', 20000.00 );
INSERT INTO COMPANY VALUES (9, 'James', 44, 'Norway', 5000.00 );
INSERT INTO COMPANY VALUES (10, 'James', 45, 'Texas', 5000.00 );
现在，我们的表具有重复名称的记录，如下所示：

ID          NAME        AGE         ADDRESS     SALARY
----------  ----------  ----------  ----------  ----------
1           Paul        32          California  20000.0
2           Allen       25          Texas       15000.0
3           Teddy       23          Norway      20000.0
4           Mark        25          Rich-Mond   65000.0
5           David       27          Texas       85000.0
6           Kim         22          South-Hall  45000.0
7           James       24          Houston     10000.0
8           Paul        24          Houston     20000.0
9           James       44          Norway      5000.0
10          James       45          Texas       5000.0
让我们用同样的 GROUP BY 语句来对所有记录按 NAME 列进行分组，如下所示：

sqlite> SELECT NAME, SUM(SALARY) FROM COMPANY GROUP BY NAME ORDER BY NAME;
这将产生以下结果：

NAME        SUM(SALARY)
----------  -----------
Allen       15000
David       85000
James       20000
Kim         45000
Mark        65000
Paul        40000
Teddy       20000
让我们把 ORDER BY 子句与 GROUP BY 子句一起使用，如下所示：

sqlite>  SELECT NAME, SUM(SALARY) 
         FROM COMPANY GROUP BY NAME ORDER BY NAME DESC;
这将产生以下结果：

NAME        SUM(SALARY)
----------  -----------
Teddy       20000
Paul        40000
Mark        65000
Kim         45000
James       20000
David       85000
Allen       15000