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编码一个存储错误值的SQL数据库

codenameone database mysql java

1

rainer · 技术社区 · 9 年前

我习惯用Java开发桌面应用程序。现在,我正在尝试代号一开发我的第一个移动应用程序。

尝试复制我使用SQL数据库的经验时,我遇到了一种非常奇怪的存储行为,我无法解释。

Database db = Display.getInstance().openOrCreate("MyDB.db");

db.execute("CREATE TABLE IF NOT EXISTS Persons (Date NOT NULL,Event NOT NULL)");




String sql = "INSERT INTO Persons (DATE , Event) " + "VALUES ( 'John', '10000.00' );"; 
db.execute (sql);

// adds "John" to the database every time I click the button 
// then I change the from "John" to "James"
// I am not adding the lines twice, just change the input



String sql = "INSERT INTO Persons (DATE , Event) " + "VALUES ( 'James', '10000.00' );"; 
db.execute (sql);

//keeps adding "John" to the database, even though value has been changed to "James" 




Cursor cur = db.executeQuery("select * from Persons;");
Row currentRow= cur.getRow();
String dataText = currentRow.getString(0);

while (cur.next()) {
             System.out.println(dataText);
        }

1 回复 | 直到 9 年前

1

3

ItamarG3 9 年前

您没有将下一行提取到 dataText while() 循环,因此您只需重复打印第一行的文本。

它应该是:

Cursor cur = db.executeQuery("select * from Persons;");
while (cur.next()) {
    Row currentRow = cur.getRow();
    String dataText = currentRow.getString("Date");
    System.out.println(dataText);
}

如果使用单独的查询工具检查表,如 PhpMyAdmin

tutorial .