使用SQLite for iPhone从数据库中获取字符串

如何解决使用SQLite for iPhone从数据库中获取字符串

|| 我有一个教程中的代码。我想知道如何修改它，以便它不会从数据库中读取双精度字，而只是读取一个字符串。

if(detailStmt == nil) {
    const char *sql = \"Select price from Coffee Where CoffeeID = ?\";
    if(sqlite3_prepare_v2(database,sql,-1,&detailStmt,NULL) != SQLITE_OK)
        NSAssert1(0,@\"Error while creating detail view statement. \'%s\'\",sqlite3_errmsg(database));
}

sqlite3_bind_int(detailStmt,1,coffeeID);

if(SQLITE_DONE != sqlite3_step(detailStmt)) {

    //Get the price in a temporary variable.
    NSDecimalNumber *priceDN = [[NSDecimalNumber alloc] initWithDouble:sqlite3_column_double(detailStmt,0)];

    //Assign the price. The price value will be copied,since the property is declared with \"copy\" attribute.
    self.price = priceDN;

    //Release the temporary variable. Since we created it using alloc,we have own it.
    [priceDN release];
}

我很确定需要更改的行是：

sqlite3_bind_int(detailStmt,coffeeID);
NSDecimalNumber *priceDN = [[NSDecimalNumber alloc] initWithDouble:sqlite3_column_double(detailStmt,0)];

我需要使用sqlite3_bind_text和sqlite3_column_text，但我不确定如何正确更改参数。 预先感谢您的帮助！     

解决方法

==新更新的答案== 我使用SQL Lite的方式与您使用的有所不同。我从未使用过

sqlite3_bind_text

。我的建议是将您的代码段替换为我提供的代码段。我试图使其涵盖您的整个代码部分。它可能需要调整一两次。 下面的解决方案应与字段和行全面工作。您只需要在

while(sqlite3_step(detailStmt) == SQLITE_ROW)

循环中使用适当的

sqlite3_column_text

，

sqlite3_column_double

，

sqlite3_column_int

或其他类型即可。如果只需要第一行，则可以将while循环更改为ѭ7

    if(detailStmt == nil) {
        const char *sql = \"Select threadtxt from Coffee Where CoffeeID = ?\";
    }    

    if (sqlite3_prepare_v2(database,sql,-1,&detailStmt,NULL) == SQLITE_OK)
    {
        // loop through the results and add them to the array
        while(sqlite3_step(detailStmt) == SQLITE_ROW) 
        {
            // read the data from the result row
            NSString *nameString = [NSString stringWithUTF8String:(char *)sqlite3_column_text(compiledStatement,0)];
            self.threadtxt = nameString;
        }   
    } else {
        NSAssert1(0,@\"Error while getting the price of coffee. \'%s\'\",sqlite3_errmsg(database));
    }

    // Release the compiled statement from memory
    sqlite3_finalize(detailStmt);