41st Day of walking into the computer (database 2 table records operations)

Insert a table record

1 Inserting a data insert

Insert [INFO] table_name (field name, ... VALUES (value: ）

2 inserting more than one data

Insert [INFO] table_name (field name, ... VALUES (value: ）

(Field name, ... VALUES (value: ）

(Field name, ... VALUES (value: ）

。。。。。。

(Field name, ... VALUES (value: ）

Two modified table records

UPDATE table_name SET field = value, field = value ... where sentence;

Three Delete table records

Delete from table_name where sentence;

TRUNCATE TABLE table_name; #将表全部删除, and then create a new table, and the fields are the same.

Four-view table records

View Syntax:

SELECT * |field1,filed2 ... From Tab_name

Where condition

Group BY Field

Have by field

Limit number of bars

The WHERE clause can be used:

Comparison operators:

> < >= <= <>! =

Between N1 and N2 values between N1 to N2

The In (N1,N2,N3) value is N1 or N2 or N3

What does like '% ' start with?

Or and not or with non-

ORDER BY clause:

Selest * | Field1,field2 .... From Tab_name order by filed [ASC | DESC]

--asc Ascending, Desc descending, where ASC is the default value the ORDER BY clause should be located in the

Select group field name, Sum (field name [int]) from Order_menu Group by Group field name

Select group field name, sum (number [int]) from Order_menu Group by Group field name having condition;

　　　　　　　　　　/* have and where both can be further filtered query results, the difference is: <1>where statement can only be used in the filter before grouping, having can be used in the filter after grouping; <2& gt; You can use the WHERE statement where you can replace the <3>having with an aggregate function, where it does not work. */

Aggregation functions:

Number of statistics Count:

Select count (field name) from Examresult;

　　　　　　Select count (field name) from Examresult where condition;

Content and sum (field name) for rows that meet the criteria:

Select SUM (field name "requires number Type") from Examresult;

Averaging AVG (field name):

Select AVG (field name "requires number Type") from Examresult;

Max, Min Max, min:

Select max (field name requires number type) from Examre;

　　　　　　Select min (field name "requires number Type") from Examre;

The end of the SELECT statement.

Limit clause:

SELECT * from Examresult limit number;

SELECT * from Examresult limit number, number;

RegExp using:

SELECT * FROM employee where emp_name regexp ' ^yu '; Start with what?

SELECT * FROM employee where emp_name regexp ' yuan$ '; At what end?

SELECT * FROM employee where Emp_name regexp ' m{2} '; Take a few

From big to small:

Take maximum

41st Day of walking into the computer (database 2 table records operations)