SQL database programming technology in JSP

SQL database programming technology in JSP
I. SQL review
1. SQL statements are divided into two types: DDL (Data Definition Language) and DML (Dat Manipulation Languge, Data operation Language ). The former mainly defines the logical structure of data, including the definition of tables, views and indexes. DML mainly queries and updates databases.
2. Create Table (DDL ):
Create Table tabName (
ColName1 colType1 [else],
ColName2 colType2 [else],
...,
ColNamen colTypen [else]
);
Example: Cteate Table pJoiner (
Pno char (6) not null,
Eno char (6) nut null
);
Char int varchar and so on are reserved words used to define the column data type. varchar indicates a variable character type.
3, Select <col1>, <col2>,..., <coln>
From <tab1>, <tab2>,..., <tabm>
[Where <condition>]

Subquery in the condition:
Where Not Exists (
Select * From tab2 Where col1 = col2
) // When the query result is null, the condition is true.

4. insert into <tab1> VALUES (<col1>,... <coln>)
5. delete from <tab1> [WHERE <condition>]
6. UPDATE <tab1>
SET <tab1 >=< vlu1>
...
<Tabn >=< vlun>
[WHERE <condition>]
For example:
Update exployee
Set age = 27
Where name = 'Zhao Yi'
2. Main JDBC interfaces:
The java. SQL. DriverManager class is used to process driver calls and support new database connections.
Java. SQL. Connection refers to the Connection between an application and a specific database.
Java. SQL. Statement, used for the execution of general SQL statements (it can be the execution process of queries, updates, or even database creation)
Java. SQL. ResultSet, the results returned by the query are saved in this object, which allows you to browse and access records in the database.