//插入
Message *message = [[Message alloc] init];
message.localID = 1;
message.content = @"Hello, WCDB!";
message.createTime = [NSDate date];
message.modifiedTime = [NSDate date];
/*
INSERT INTO message(localID, content, createTime, modifiedTime)
VALUES(1, "Hello, WCDB!", 1496396165, 1496396165);
*/
BOOL result = [database insertObject:message
into:@"message"];
//删除
//DELETE FROM message WHERE localID>0;
BOOL result = [database deleteObjectsFromTable:@"message"
where:Message.localID > 0];
//修改
//UPDATE message SET content="Hello, Wechat!";
Message *message = [[Message alloc] init];
message.content = @"Hello, Wechat!";
BOOL result = [database updateRowsInTable:@"message"
onProperties:Message.content
withObject:message];
//查询
//SELECT * FROM message ORDER BY localID
NSArray<Message *> *message = [database getObjectsOfClass:Message.class
fromTable:@"message"
orderBy:Message.localID.order()];
事务一
BOOL commited = [database runTransaction:^BOOL {
[database insertObject:message into:@"message"];
return YES; //return YES to commit transaction and return NO to rollback transaction.
}];
事务二
WCTTransaction *transaction = [database getTransaction];
BOOL result = [transaction begin];
[transaction insertObject:message into:@"message"];
result = [transaction commit];
if (!result) {
[transaction rollback];
NSLog(@"%@", [transaction getError]);
}
事务（Transaction），一般是指要做的或所做的事情。在计算机术语中是指访问并可能更新数据库中各种数据项的一个程序执行单元(unit)。事务(Transaction)是访问并可能更新数据库中各种数据项的一个程序执行单元(unit)。事务通常由高级数据库操纵语言或编程语言（如SQL，C++或Java）书写的用户程序的执行所引起，并用形如begin transaction和end transaction语句（或函数调用）来界定。事务由事务开始(begin transaction)和事务结束(end transaction)之间执行的全体操作组成。
