Anderson

basic

SELECT — used to query and display data from a database. The SELECT statement specifies which columns to include in the result set. The vast majority of the SQL commands used in applications are SELECT statements.
INSERT — adds new rows to a table. INSERT is used to populate a newly created table or to add a new row (or rows) to an already-existing table.
DELETE — removes a specified row or set of rows from a table
UPDATE — changes an existing value in a column or group of columns in a table

The more common DDL commands follow:

CREATE TABLE — creates a table with the column names the user provides. The user also needs to specify a type for the data in each column. Data types vary from one RDBMS to another, so a user might need to use metadata to establish the data types used by a particular database. CREATE TABLE is normally used less often than the data manipulation commands because a table is created only once, whereas adding or deleting rows or changing individual values generally occurs more frequently.

DROP TABLE — deletes all rows and removes the table definition from the database. A JDBC API implementation is required to support the DROP TABLE command as specified by SQL92, Transitional Level. However, support for the CASCADE and RESTRICT options of DROP TABLE is optional. In addition, the behavior of DROP TABLE is implementation-defined when there are views or integrity constraints defined that reference the table being dropped.

ALTER TABLE — adds or removes a column from a table. It also adds or drops table constraints and alters column attributes

jdbc

The following simple code fragment gives a simple example of these three steps:
++++ ConnectionSource.getConnection( "#","#","#"); ???? dbcp

Connection con = DriverManager.getConnection
( "jdbc:myDriver:wombat", "myLogin","myPassword");

Statement stmt = con.createStatement();
PreparedStatement pstmt=conn. prepareStatement(SQL);
ResultSet rs = stmt.executeQuery("SELECT a, b, c FROM Table1");
while (rs.next()) {
int x = rs.getInt("a");
String s = rs.getString("b");
float f = rs.getFloat("c");
}

Jstl

<sql:update var="user" dataSource="${dataSource} " >
insert into tb_user (username,password) values (?,?)
<sql:param value="${param.username}" />
<sql:param value="${param[ password]}" />
</sql:update>
<c:redirect url="listUser.jsp">

< %@taglib url=" http://java.sun.com/jsp/jstl/core " prefix="c" %>
< %@taglib url=" http://java.sun.com/jsp/jstl/fuction " prefix="fn"%>
< %@taglib url=" http://java.sun.com/jsp/jstl/sql " prefix="sql"%>
< %@taglib url="/struts-taglibs" prefix="s" %>

<sql:query var="rs" dataSource="${dataSoure}">
select * from tb_user
</sql:query>
<table >
<tr>
<th width=20%>#</th>
<th>#</th>
<th>#</th>
<th>#</th>
</tr>
<c:forEach var="user" item="${rs.rows}" >
<tr>
<td width=20%>${user.usename}</td>
<td>${user.password}</td>
<td><a href="editUser!input.jsp?id=${user.id}">編輯</a></td>
<td><a href="javascript:if(confirm('are you sure?'){document.location.href='deleteUserAction.jsp?id=${user.id}'};)">刪除</a></td>
</tr>
</c:forEach>

1.core_Tags
< %@taglib uri=" http://java.sun.com/jsp/jstl/core " prefix="c"%>
<c:set var="變量名" scope="page/session/request/application" value="值"/>
<c:set var="變量名" scope="page/session/request/application">值</c:set>
<c:remove var="變量名" scope="page/session/request/application"/>
<c:out value=${}/} 從小到大的范圍查找變量
**********************************************************
<c:if test="${empty var}"></c:if>
**********************************************************
<c:choose>
<c:when test="${pageScope.var/session.var/...}"></c:when>
<c:when test="${}"></c:when>
<c:otherwise></c:otherwise>
</c:choose>
**********************************************************
<c:forEach items="包含要迭代的內容的數據結構對象 "
var="用戶指定的當前正在迭代的元素"
varStatus="當前元素的狀態(count|index|first|last)" count執行的次數，index索引值，first是否為第一個,last是否為最后一個
begin="迭代開始的位置 "
end="迭代結束的位置"
step="迭代的步長" >
</forEach>
**********************************************************eg:
<c:forTokens items="字符串" var="當前字符串" varStatus="" delims="定界符">
</c:forTokens>
**********************************************************
<c:import uri="" var=""/>
<c:url value="">
<c:param name="" value=""/>
</c:url>
<c:redirect url=""/>

2
.sql_Tags
< %@taglib uri=" http://java.sun.com/jsp/jstl/core " prefix="sql"%>
連接
<sql:setDataSource var="" dirver="" url="" user="" password=""/>
操作
<sql:query dateSource="${}" var=" 結果集">select</sql:query>
<sql:update dateSource="${}">insert</sql:query>
<sql:update dateSource="${}">delete</sql:query>
事務
<sql:transaction dataSource="">
<sql:update var="">insert/update/delete</sql:update>
<sql:query var="">select</sql:query>
</sql:transaction>
顯示
<c:forEach items="${結果集.rows}" var="記錄" varStatus="s">
<h1 align="center">${s.count}|${ 記錄 .dd}</h1>
</c:forEach>