基于ID的Objective C Sqlite更新查询

Question

尝试在不使用包装器的情况下学习 Sqlite，并且已经管理了大多数事情，但我真的停留在 UPDATE 查询上

我正在尝试根据其 _ID 编号更新一列中的字符串，该编号是主键并且是唯一的。

我已经尝试了来自 google 的各种代码。这个说它已经工作了，但是当我检查该列时没有更新

这里是代码

            NSDateFormatter *formatter;
            NSString        *dateString;
            formatter = [[NSDateFormatter alloc] init];
            [formatter setDateFormat:@"dd-MM-yyyy HH:mm"];
            dateString = [formatter stringFromDate:[NSDate date]];
            NSString *IDCODE = code.stringValue;
           NSInteger b = [IDCODE integerValue];
            sqlite3 *contactDB; //Declare a pointer to sqlite database structure
            const char *dbpath = [dbPath UTF8String]; // Convert NSString to UTF-8
            if (sqlite3_open(dbpath, &contactDB) == SQLITE_OK)
            {
                //Database opened successfully
                NSString *databaseName = @"vistorlog.db";
                // Get the path to the documents directory and append the databaseName
                NSArray *documentPaths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
                NSString *documentsDir = [documentPaths objectAtIndex:0];
                NSString *databasePath = [documentsDir stringByAppendingPathComponent:databaseName];
                const char *dbPath=[databasePath UTF8String];
                if (sqlite3_open(dbPath, &myDB)==SQLITE_OK) {
                    NSLog(@"database Opened");
                    const char* updateQuery="update LOG set TIMEOUT='22/03/19' where _ID=1";
                    sqlite3_stmt *stmt;
                    if (sqlite3_prepare_v2(myDB, updateQuery, -1, &stmt, NULL)==SQLITE_OK) {
                        NSLog(@"Query Executed");
                    }else{
                         NSLog(@"Query NOT Executed");
                                               }
                }
                sqlite3_close(myDB);
                }
                else {
                //Failed to open database
            }

它打开数据库vistorlog.db ok。有一个名为 LOG 的表，有一个名为 TIMEOUT 的列，我希望在其中更新字符串，还有一个名为 _ID 的列，这是我查询的基础，但它不会更新

最终我希望更新语句使用字符串变量 dateString 作为要更新的字符串，使用 b 作为 _ID 的整数变量

任何想法我哪里出错了？

任何帮助表示赞赏

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编辑

更新查询的工作代码

sqlite3 *contactDB; //Declare a pointer to sqlite database structure
            const char *dbpath = [dbPath UTF8String]; // Convert NSString to UTF-8
            if (sqlite3_open(dbpath, &contactDB) == SQLITE_OK)
            {
                //Database opened successfully
                NSString *databaseName = @"vistorlog.db";
                // Get the path to the documents directory and append the databaseName
                NSArray *documentPaths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
                NSString *documentsDir = [documentPaths objectAtIndex:0];
                NSString *databasePath = [documentsDir stringByAppendingPathComponent:databaseName];
                const char *dbPath=[databasePath UTF8String];
                if (sqlite3_open(dbPath, &myDB)==SQLITE_OK) {
                    NSLog(@"database Opened");

// define dateString and IDCODE as strings before this
                    const char *updateQuery = "Update log set TIMEOUT=? where _ID=?";
                    sqlite3_stmt *stmt;
                    // Prepare Stment
                    if (sqlite3_prepare_v2(myDB, updateQuery, -1, &stmt, NULL) == SQLITE_OK) {
                        sqlite3_bind_text(stmt, 1, [dateString UTF8String], -1, SQLITE_TRANSIENT);
                        sqlite3_bind_text(stmt, 2, [IDCODE UTF8String], -1, SQLITE_TRANSIENT);                            if(sqlite3_step(stmt) == SQLITE_DONE) {
                            NSLog(@"Query Executed");
                        } else {
                            NSLog(@"Query NOT Executed: %s", sqlite3_errmsg(myDB));
                        }
                        sqlite3_finalize(stmt);

                    }else{
                        NSLog(@"Statement NOT Prepared: %s", sqlite3_errmsg(myDB));
                    }
                }
                sqlite3_close(myDB);
                }
                else {
                //Failed to open database
            }

别忘了导入 sqlite3.h

标记

Answer 1

您只是在准备语句，而不是实际执行它。

执行sqlite3_prepare_v2后需要执行sqlite3_step()

if (sqlite3_prepare_v2(myDB, updateQuery, -1, &stmt, NULL) == SQLITE_OK) {
    if(sqlite3_step(stmt) == SQLITE_DONE) {
        NSLog(@"Query Executed");       
    } else {
        NSLog(@"Query NOT Executed: %s", sqlite3_errmsg(myDB));
    }
    sqlite3_finalize(stmt);

}else{
    NSLog(@"Statement NOT Prepared: %s", sqlite3_errmsg(myDB));
}