SQL syntax and ADO summary

First, SQL syntax

1. Query Statement Select

SELECT * FROM table name where query condition

2. Delete statements

Delete table name where delete condition

3. INSERT statement Inserts

Insert into table name (Field 1, Field 2) VALUES (' Value 1 ', ' Value 2 ')

4. Modify Statement Update

Update table name Set field = new value where modify condition

5. SQL statement Operations Database and table

drop table name//delete data table

Create DATABASE Database name//databases created

Drop database name//delete data bitter

ALTER TABLE name add field name data type//data table added field

ALTER TABLE Name drop column field name//Data table Delete field

ALTER TABLE name ALTER COLUMN field name new data type//modify field data type

Second, the use of the ADO object

1. SqlConnection class: Create a Database link object

SqlConnection conn=new SqlConnection ("server= server name; uid= user; pwd= password; database= database name");

2. SqlCommand class: The object that executes the SQL statement

SqlConnection conn=new SqlConnection ("server= server name; uid= user; pwd= password; database= database name");

String cmdstr= "select * from Student";

SqlCommand cmd=new SqlCommand (Cmdstr,con);

3. SqlDataReader class: Create an object that queries one or more data

SqlConnection conn=new SqlConnection ("server= server name; uid= user; pwd= password; database= database name");

String cmdstr= "select * from Student";

SqlCommand cmd=new SqlCommand (Cmdstr,con);

SqlDataReader Reader=cmd. ExecuteReader ();

4. SqlDataAdapter class: Create an object to retrieve and persist data

SqlConnection conn=new SqlConnection ("server= server name; uid= user; pwd= password; database= database name");

String cmdstr= "select * from Student";

SqlCommand cmd=new SqlCommand (Cmdstr,con);

SqlDataAdapter Adapter=new SqlDataAdapter (CMD);

5. DataSet class: Create a local data store object

SqlConnection conn=new SqlConnection ("server= server name; uid= user; pwd= password; database= database name");

String cmdstr= "select * from Student";

SqlCommand cmd=new SqlCommand (Cmdstr,con);

SqlDataAdapter Adapter=new SqlDataAdapter (CMD);

DataSet ds=new DataSet ();

Adapter. Fill (DS);

This article from the "Search in the Wind" blog, declined to reprint!

SQL syntax and ADO summary