在运行时创建的 SQLite 数据库中执行查询后显示结果时出现问题。
这是我的代码
创建数据库
var mydb=false;
// initialise the database
initDB = function() {
try {
if (!window.openDatabase) {
alert('not supported');
} else {
var shortName = 'APP_DB';
var version = '0.1';
var displayName = 'It Happened Today DB';
var maxSize = 262144; // in bytes, 256kb
mydb = openDatabase(shortName, version, displayName, maxSize);
}
} catch(e) {
// Error handling code goes here.
if (e == INVALID_STATE_ERR) {
// Version number mismatch.
alert("Invalid database version.");
} else {
alert("Unknown error "+e+".");
}
return;
}
}
// db error handler - prevents the rest of the transaction going ahead on failure
errorHandler = function (transaction, error) {
// returns true to rollback the transaction
return true;
}
// null db data handler
nullDataHandler = function (transaction, results) { }
创建表和插入值
// create tables for the database
createTables = function() {
try {
mydb.transaction(
function(transaction) {
transaction.executeSql('CREATE TABLE milestones (ID INT( 10 ) NOT NULL, Title VARCHAR( 50 ) DEFAULT NULL, mYear INT( 11 ) NOT NULL, mMonth INT( 11 ) DEFAULT NULL, mDay VARCHAR( 10 ) DEFAULT NULL, mText VARCHAR( 2000 ) NOT NULL, Theme1 VARCHAR( 50 ) DEFAULT NULL, Theme2 VARCHAR( 50 ) DEFAULT NULL, ImageURL VARCHAR( 50 ) DEFAULT NULL, PRIMARY KEY ( ID ));', [], nullDataHandler, errorHandler);
transaction.executeSql('INSERT INTO [milestones] ([ID], [Title], [mYear], [mMonth], [mDay], [mText], [Theme1], [Theme2], [ImageURL]) VALUES (2, "Cotton Mather", 1721, 6, 26, "Following the recommendation of Rev. Cotton Mather, Dr. Zabdiel Boylston of Boston completes the first inoculation against smallpox in the U.S., injecting his own son and two of his slaves.", "HIAm", null, "6-26 Cotton Mather3g04597v.jpg");', [], nullDataHandler, errorHandler);
transaction.executeSql('INSERT INTO [milestones] ([ID], [Title], [mYear], [mMonth], [mDay], [mText], [Theme1], [Theme2], [ImageURL]) VALUES (6, "New York Hospital", 1771, 6, 13, "New York Hospital, the second in the colonies after the Pennsylvania Hospital, receives a royal charter from King George III under the name Society of the Hospital in the City of New York in America, later changed to Society of New York Hospital.", "HIAm", null, "Default.png");', [], nullDataHandler, errorHandler);
});
} catch(e) {
/// alert(e.message);
return;
}
};
文本2HTML
milestonesDataHandler = function(transaction, results){
var html = "";
for(var i=0; i < results.rows.length; i++){
var row = results.rows.item(i);
html += '<li class="elist"> \
<a href="article.template.html?id=">'+row['id']+'data-transition="none"> \
<img src="img/">'+row['ImageURL']+'" height="70" width="70" /> \
<h4>'+row['Title']+'</h4> \
<p>'+ dateFormat($row['mYear']+' '+$row['mMonth']+' '+$row['mDay'])+'</p> \
</a> \
</li>';
}
}
执行查询
loadMilestones = function(){
try {
mydb.transaction(
function(transaction){
transaction.executeSql("SELECT * FROM milestones", [], milestonesDataHandler, errorHandler);
});
}
catch(e) {
alert(e.message);
}
}
在 HTML 文档的末尾,我这样做:
<script>$("div.miles").html(milestonesDataHandler);</script>
什么都没有显示。当我转到 Chrome 调试器时,它说:131 Uncaught TypeError: Cannot read property 'length' for undefined。
这是指 TEXT2HTML 部分的第 3 行。看起来由于某种原因,结果变量没有被填充。
请你帮我解决这个问题。
谢谢